SPACE IS NOT EMPTY
Hubble Space Telescope sees supernova wreckage in a hazy galaxy (image)
Samantha Mathewson
Tue, November 7, 2023
A blue and white spiral galaxy in the black of space.
The Hubble Space Telescope snapped a new view of a hazy spiral galaxy that once hosted a supernova explosion.
The galaxy, formally known as NGC 941, lies about 55 million light-years from Earth. Its spiral arms are bright but not very well defined, swirling outward from a bright core into a faint halo of dimmer gas.
Hubble’s Advanced Camera for Surveys (ACS) observed the remnants of a stellar explosion within the galaxy. When some stars reach the end of their lives, they explode in a brilliant burst called a supernova, which can briefly outshine the entire galaxy in which it sits. This particular supernova, known as SN 2005ad, has since faded, leaving behind seeds for future star formation.
Hubble's view captures the galaxy face-on, showcasing the realm's spiral structure and hazy surroundings. Using the Hubble data, SN 2005ad was also studied as part of a larger initiative to understand the environments in which hydrogen-rich supernovae, known as Type II, occur following the rapid collapse of a massive star, according to a statement from the European Space Agency (ESA).
However, the initial discovery of supernova SN 2005ad was made by an amateur astronomer named Kōichi Itagaki, who has discovered over 170 supernovae, according to the statement.
"This might raise the question of how an amateur astronomer could spot something like a supernova event before professional astronomers — who have access to telescopes such as Hubble," ESA officials said in the statement. "The answer is in part that the detection of supernovae is a mixture of skill, facilities and luck."
Supernovas can be detected by looking for brightness variations in the sky. These stellar explosions happen relatively fast, appearing very suddenly and then brightening and dimming over a period of days or weeks.
The amount of data Hubble collects in only a few hours of observations might take weeks, months, or even years, to process and analyze, which is why amateur astronomers play a key role in helping comb through the space telescope’s images. Amateur astronomers are also able to spend much more time actually observing the skies than professional astronomers who are assigned to specific tasks.
Many amateur astronomers have their own system of telescopes, computers and software that allow them to monitor the skies and detect astronomical events that may otherwise be missed — such as a supernova explosion. An online system, called the Transient Name Server, was established for reporting such discoveries.
"This is a big help to professional astronomers, because with supernova events time is truly of the essence," ESA officials said.
After Itagaki reported the discovery of SN 2005ab, professional astronomers were able to follow up with spectroscopic studies and confirm it as a type II supernova. Then, Hubble was aimed in the direction of NGC 941 to get a better view of the supernova and its surrounding environment, which astronomers might not have otherwise included in their study.
"Such a study wouldn’t be possible without a rich library of previous supernovae, built with the keen eyes of amateur astronomers," ESA officials said.
ESA released the new Hubble photo of NGC 941 online on Monday (Nov. 6).
James Webb Space Telescope watches infant galaxies bringing light to the early universe
Samantha Mathewson
Tue, November 7, 2023
A blue and white spiral galaxy in the black of space.
The Hubble Space Telescope snapped a new view of a hazy spiral galaxy that once hosted a supernova explosion.
The galaxy, formally known as NGC 941, lies about 55 million light-years from Earth. Its spiral arms are bright but not very well defined, swirling outward from a bright core into a faint halo of dimmer gas.
Hubble’s Advanced Camera for Surveys (ACS) observed the remnants of a stellar explosion within the galaxy. When some stars reach the end of their lives, they explode in a brilliant burst called a supernova, which can briefly outshine the entire galaxy in which it sits. This particular supernova, known as SN 2005ad, has since faded, leaving behind seeds for future star formation.
Hubble's view captures the galaxy face-on, showcasing the realm's spiral structure and hazy surroundings. Using the Hubble data, SN 2005ad was also studied as part of a larger initiative to understand the environments in which hydrogen-rich supernovae, known as Type II, occur following the rapid collapse of a massive star, according to a statement from the European Space Agency (ESA).
However, the initial discovery of supernova SN 2005ad was made by an amateur astronomer named Kōichi Itagaki, who has discovered over 170 supernovae, according to the statement.
"This might raise the question of how an amateur astronomer could spot something like a supernova event before professional astronomers — who have access to telescopes such as Hubble," ESA officials said in the statement. "The answer is in part that the detection of supernovae is a mixture of skill, facilities and luck."
Supernovas can be detected by looking for brightness variations in the sky. These stellar explosions happen relatively fast, appearing very suddenly and then brightening and dimming over a period of days or weeks.
The amount of data Hubble collects in only a few hours of observations might take weeks, months, or even years, to process and analyze, which is why amateur astronomers play a key role in helping comb through the space telescope’s images. Amateur astronomers are also able to spend much more time actually observing the skies than professional astronomers who are assigned to specific tasks.
Many amateur astronomers have their own system of telescopes, computers and software that allow them to monitor the skies and detect astronomical events that may otherwise be missed — such as a supernova explosion. An online system, called the Transient Name Server, was established for reporting such discoveries.
"This is a big help to professional astronomers, because with supernova events time is truly of the essence," ESA officials said.
After Itagaki reported the discovery of SN 2005ab, professional astronomers were able to follow up with spectroscopic studies and confirm it as a type II supernova. Then, Hubble was aimed in the direction of NGC 941 to get a better view of the supernova and its surrounding environment, which astronomers might not have otherwise included in their study.
"Such a study wouldn’t be possible without a rich library of previous supernovae, built with the keen eyes of amateur astronomers," ESA officials said.
ESA released the new Hubble photo of NGC 941 online on Monday (Nov. 6).
James Webb Space Telescope watches infant galaxies bringing light to the early universe
Robert Lea
Tue, November 7, 2023
A distant emission line seen by the JWST (left) and by Hubble (right) .
Baby galaxies in the early universe ignited gas to trigger explosions of intense star formation, according to new observations from the James Webb Space Telescope (JWST).
Many early galaxies like the ones the JWST detected were rich with glowing gas so bright that the gas itself could outshine stars emerging from within.
These new findings reveal just how common such shimmering, infant, gassy galaxies were when the 13.8 billion-year-old universe was around only 2 billion years old. The team behind this research found that almost 90% of the galaxies had so-called "extreme emission features," meaning they exhibited all that glowing gas.
A distant emission line seen by the JWST (left) and by Hubble (right)
"The stars in these young galaxies were remarkable, producing just the right amount of radiation to excite the surrounding gas. This gas, in turn, shone even brighter than the stars themselves," research lead author and ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) scientist Anshu Gupta said in a statement. "Until now, it was challenging to understand how these galaxies were able to accumulate so much gas.
"Our findings suggest that each of these galaxies had at least one close neighboring galaxy. The interaction between these galaxies would cause gas to cool and trigger an intense episode of star formation, resulting in this extreme emission feature."
Related: James Webb Space Telescope could soon solve mysteries of the Milky Way’s heart
The discovery confirms the assumptions of astronomers who suspected these extreme galaxies are indicators of intense interactions in the early universe.
"What’s really exciting about this piece is that we see emission line similarities between the very first galaxies to galaxies that formed more recently and are easier to measure," team member and Curtin University researcher Ravi Jaiswar said. "This means we now have more ways to answer questions about the early universe, a period that is technically very hard to study."
The James Webb Space Telescope is paying off
Images of a distant extreme emission line galaxy. Seen by James Webb Space Telescope (left) and Hubble Space Telescope (right). This comparison highlights the clarity of JWST images.
This new conclusion is yet another example of how the JWST was worth every penny of its $10 billion cost — prior to this, astronomers simply hadn’t been able to get a clear picture of star-forming galaxies that existed around 12 billion years ago.
"The data quality from the James Webb telescope is exceptional. It has the depth and resolution needed to see the neighbors and environment around early galaxies from when the universe was only 2 billion years old," Gupta said. "With this detail, we were able to see a marked difference in the number of neighbors between galaxies with the extreme emission features and those without."
The data used by the team was collected as part of the JWST Advanced Deep Extragalactic Survey (JADES) survey, the goal of which is to explore the earliest galaxies and open the door to future insights.
"Prior to JWST, we could only really get a picture of really massive galaxies, most of which are in really dense clusters, making them harder to study," Gupta concluded. "With the technology available then, we couldn’t observe 95% of the galaxies we used in this study.
"The JWST has revolutionized our work."
The team’s research is published in the Astrophysical Journal.
Tue, November 7, 2023
A distant emission line seen by the JWST (left) and by Hubble (right) .
Baby galaxies in the early universe ignited gas to trigger explosions of intense star formation, according to new observations from the James Webb Space Telescope (JWST).
Many early galaxies like the ones the JWST detected were rich with glowing gas so bright that the gas itself could outshine stars emerging from within.
These new findings reveal just how common such shimmering, infant, gassy galaxies were when the 13.8 billion-year-old universe was around only 2 billion years old. The team behind this research found that almost 90% of the galaxies had so-called "extreme emission features," meaning they exhibited all that glowing gas.
A distant emission line seen by the JWST (left) and by Hubble (right)
"The stars in these young galaxies were remarkable, producing just the right amount of radiation to excite the surrounding gas. This gas, in turn, shone even brighter than the stars themselves," research lead author and ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) scientist Anshu Gupta said in a statement. "Until now, it was challenging to understand how these galaxies were able to accumulate so much gas.
"Our findings suggest that each of these galaxies had at least one close neighboring galaxy. The interaction between these galaxies would cause gas to cool and trigger an intense episode of star formation, resulting in this extreme emission feature."
Related: James Webb Space Telescope could soon solve mysteries of the Milky Way’s heart
The discovery confirms the assumptions of astronomers who suspected these extreme galaxies are indicators of intense interactions in the early universe.
"What’s really exciting about this piece is that we see emission line similarities between the very first galaxies to galaxies that formed more recently and are easier to measure," team member and Curtin University researcher Ravi Jaiswar said. "This means we now have more ways to answer questions about the early universe, a period that is technically very hard to study."
The James Webb Space Telescope is paying off
Images of a distant extreme emission line galaxy. Seen by James Webb Space Telescope (left) and Hubble Space Telescope (right). This comparison highlights the clarity of JWST images.
This new conclusion is yet another example of how the JWST was worth every penny of its $10 billion cost — prior to this, astronomers simply hadn’t been able to get a clear picture of star-forming galaxies that existed around 12 billion years ago.
"The data quality from the James Webb telescope is exceptional. It has the depth and resolution needed to see the neighbors and environment around early galaxies from when the universe was only 2 billion years old," Gupta said. "With this detail, we were able to see a marked difference in the number of neighbors between galaxies with the extreme emission features and those without."
The data used by the team was collected as part of the JWST Advanced Deep Extragalactic Survey (JADES) survey, the goal of which is to explore the earliest galaxies and open the door to future insights.
"Prior to JWST, we could only really get a picture of really massive galaxies, most of which are in really dense clusters, making them harder to study," Gupta concluded. "With the technology available then, we couldn’t observe 95% of the galaxies we used in this study.
"The JWST has revolutionized our work."
The team’s research is published in the Astrophysical Journal.
Farthest black hole ever recorded by astronomers is nearly as old as our universe
Laura Baisas
Tue, November 7, 2023
Astronomers found the most distant black hole ever detected in X-rays (in a galaxy dubbed UHZ1) using the Chandra X-Ray Observatory and the James Webb Space Telescope. X-ray emission is a telltale signature of a growing supermassive black hole. This result may explain how some of the first supermassive black holes in the universe formed. These images show the galaxy cluster Abell 2744 that UHZ1 is located behind, in X-rays from Chandra and infrared data from JWST, as well as close-ups of the black hole host galaxy UHZ1.
Astronomers have discovered the most distant supermassive black hole ever observed. They had the help of a “cosmic magnifying glass,” or gravitational lensing. This happens when a massive celestial body creates a large curvature of spacetime so that the path of light around it can be bent as if by a lens.
The black hole is located in the galaxy UHZ1 in the direction of the galaxy cluster Abell 2744. The galaxy cluster is about 13.2 billion-years-old. The team used NASA’s Chandra X-ray Observatory and the James Webb Space Telescope (JWST) to find the telltale signature of a growing black hole. It started to form only 470 million years after the big bang when the universe was only 3 percent of its current age of about 13.7 billion years-old. The galaxy is much more distant than the cluster itself, at 13.2 billion light-years from Earth.
Astronomers can tell that this black hole is so young because it is so giant. Black holes evaporate over time. Most black holes in galactic centers have a mass that is equal to roughly a tenth of the stars in their host galaxy, according to NASA. This early black hole is growing and as a mass that is on par with our entire galaxy. Astronomers have never witnessed a black hole at this stage before and studying it could help explain how some of the first supermassive black holes in the universe formed. The findings are detailed in a study published November 6 in the journal Nature Astronomy.
“We needed Webb to find this remarkably distant galaxy and Chandra to find its supermassive black hole,” study co-author and astronomer Akos Bogdan said in a statement. Bogdan is affiliated with the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.
“We also took advantage of a cosmic magnifying glass that boosted the amount of light we detected,” Bogman added. This magnifying effect is known as gravitational lensing. The team took X-ray observations with Chandra for two weeks. They saw intense, superheated X-ray emitting gas—a supermassive black hole’s trademark—from the galaxy. The light coming from the galaxy and the X-ray from the gas around the supermassive black hole were magnified by the hot gas and dark matter coming from the galaxy cluster. This effect was like a “cosmic magnifying glass” and it enhanced the infrared light signals that the JWST could detect and allowed Chandra to see the faint X-ray source.
“There are physical limits on how quickly black holes can grow once they’ve formed, but ones that are born more massive have a head start. It’s like planting a sapling, which takes less time to grow into a full-size tree than if you started with only a seed,” study co-author and Princeton University astronomer Andy Goulding said in a statement.
Observing this phenomenon could help astronomers answer how some supermassive black holes can hit enormous masses so soon after the explosion of energy from the big bang. There are two opposed theories for the origin of these supermassive black holes–light seed versus heavy seed. The light seed theory says that a star will collapse into a stellar mass black hole and then grow into a supermassive black hole over time. In the heavy seed theory, a large cloud of gas–not an individual star–collapses and condenses to form the supermassive black hole. This newly discovered black hole could confirm the heavy seed theory.
“We think that this is the first detection of an ‘Outsize Black Hole’ and the best evidence yet obtained that some black holes form from massive clouds of gas,” study co-author and Yale University theoretical astrophysicist Priyamvada Natarajan said in a statement. “For the first time we are seeing a brief stage where a supermassive black hole weighs about as much as the stars in its galaxy, before it falls behind.”
The team plans to use this and more data coming in from the JWST and other space telescopes to create a better picture of the early universe.
This supermassive black hole is the most distant ever seen in X-rays
Keith Cooper
Tue, November 7, 2023
Shown is the galaxy cluster Abell 2744, with the distant galaxy UHZ1 that formed just 470 million years after the Big Bang. It was imaged by the Chandra X-Ray Observatory and the James Webb Space Telescope (inset). The blue glow is X-rays from the hot gas in the cluster, and inset, from hot gas around the black hole at the center of UHZ1.More
A newly found black hole is shattering records, revealing new things about how such objects formed.
Two space telescopes paired up to examine a giant black hole that has a mass approximately equal to the galaxy that hosts it. It's an early starter: the galaxy existed just 470 million years after the Big Bang that formed our universe about 13.8 billion years ago. The existence of this black hole is, therefore, a huge clue as to how supermassive black holes at the center of galaxies form.
Black holes are very dense objects with such intense gravity that even light cannot escape, if it strays too close. The new black hole is a record breaker: the most distant yet observed in X-rays. As such, the observations from NASA's James Webb Space Telescope (Webb or JWST) and the agency's Chandra X-ray Observatory capture the black hole in a stage of its growth never before seen.
Related: Black holes: Everything you need to know
The JWST first spotted the feeble light of the early galaxy, called UHZ1. The mass of the galaxy is approximately 140 million times the mass of the sun. JWST saw the galaxy due to gravitational lensing, when the gravity of a massive foreground galaxy cluster, Abell 2744, amplified the light of UHZ1.
When Chandra followed up on UHZ1 and observed it for two weeks, it detected powerful X-rays coming from a disk of gas swirling around in the gravitational field of a supermassive black hole at the core of the distant galaxy.
"We needed Webb to find this remarkably distant galaxy, and Chandra to find its supermassive black hole," Ákos Bogdán of the Harvard–Smithsonian Center for Astrophysics, said in a statement Monday (Nov. 6). Bogdán is the lead author of a paper in Nature Astronomy describing the X-ray observations and signature of the black hole, mainly based on Chandra but also including Webb data.
Judging by the brightness and intensity of the X-rays, which are connected to the strength of the black hole's gravity, the black hole has a mass of the order of tens of millions to hundreds of millions of solar masses, equivalent to the mass of its host galaxy.
Related: Star-birthing galaxies can hide supermassive black holes behind walls of dust
The Chandra X-Ray Observatory and its upper stage are seen in this photo taken by an astronaut on the space shuttle Columbia just after the space telescope was deployed in orbit on July 23, 1999.
UHZ1 is still fairly small for a galaxy, however. Models of galaxy formation describe how they begin small and then grow through mergers, either with other galaxies or gigantic intergalactic gas clouds. What isn't understood very well is how their supermassive black holes form.
There are two candidate theories to explain their formation. One is that they formed through rapid mergers of stellar-mass black holes produced by exploding stars. The other possibility is that supermassive black holes formed directly from a collapsing gas cloud that had a mass between 10,000 and 100,000 times that of the sun.
The new research suggests the newfound black hole was born large, with an estimated mass of roughly 10 million and 100 million suns when calculating the X-rays' brightness and energy.
"There are physical limits on how quickly black holes can grow once they’ve formed, but ones that are born more massive have a head start. It’s like planting a sapling, which takes less time to grow into a full-size tree than if you started with only a seed," said Andy Goulding of Princeton University. Goulding is lead author of a Sept. 22 paper in The Astrophysical Journal Letters that reports the galaxy’s distance and mass, and co-author on the new Nature Astronomy paper.
The brightness and energy of the X-rays are in the realm predicted in calculations by theoretical astrophysicist Priyamvada Natarajan of Yale University, which lead to the creation of "outsize black holes" that form directly from gas cloud collapse.
"We think that this is the first detection of an outsize black hole, and the best evidence yet obtained that some black holes form from massive clouds of gas," Natarajan said in the same statement. "For the first time, we are seeing a brief stage where a supermassive black hole weighs about as much as the stars in its galaxy, before it falls behind."
In most modern galaxies, the supermassive black hole amounts to only a tenth of the mass of its host galaxy. The mass of the black hole is also correlated to the stellar mass of a spiral galaxy's central bulge, or the overall mass of an elliptical galaxy. By witnessing an active black hole in this stage of growth, the observations could shed light on how this correlation occurs. Either way, UHZ1 certainly has a lot of growing to do to outpace the growth of its black hole.
Telescopes spot the oldest and most distant black hole formed after the big bang
Ashley Strickland, CNN
Tue, November 7, 2023
NASA/ESA/CSA/STScI/CXC/SAO/Ákos Bogdán/L. Frattare & K. Arcand
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Two powerful NASA telescopes have detected the oldest and most distant black hole ever found.
Data captured via energetic X-rays by the Chandra X-ray Observatory and James Webb Space Telescope has helped astronomers spot the signature of a growing black hole within the early universe just 470 million years after the big bang, which occurred 13.8 billion years ago.
The discovery, described in a study published Monday in the journal Nature Astronomy, may help astronomers piece together how some of the first supermassive black holes formed in the cosmos.
“We needed Webb to find this remarkably distant galaxy and Chandra to find its supermassive black hole,” said lead study author Akos Bogdan, in a statement. “We also took advantage of a cosmic magnifying glass that boosted the amount of light we detected.” Bogdan is an astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.
He was referring to an effect called gravitational lensing, which occurs when closer objects — in this case a galactic cluster — act like a magnifying glass for distant objects. Gravity essentially warps and amplifies the light of distant galaxies in the background of whatever is doing the magnifying, enabling observations of otherwise invisible celestial features.
Astronomers detected the black hole in a galaxy called UHZ1. At first glance, the galaxy appeared in the same direction as a cluster of galaxies known as Abell 2744, which is located about 3.5 billion light-years from Earth. But data collected by the Webb telescope showed that UHZ1 is actually much farther away and located beyond the cluster at 13.2 billion light-years from Earth.
A light-year, equivalent to 5.88 trillion miles, is how far a beam of light travels in a year. Given the distance between Earth and the objects from the early days of the universe, when telescopes like Webb observe this light, it’s effectively like looking into the past.
The team used the Chandra Observatory to detect superheated gas releasing X-rays within UHZ1, the telltale sign of a supermassive black hole growing in size.
The detection was made possible by the Abell cluster of galaxies, which intensified the light of the UHZ1 galaxy and the X-rays released by the black hole by a factor of four.
Decoding a cosmic mystery
Astronomers think the discovery will help them to better understand how supermassive black holes appeared and reached their monstrous masses so soon after the beginning of the universe.
The researchers want to know whether the giant celestial objects formed when massive clouds of gas collapsed or if they resulted from the explosions of the very first massive stars.
“There are physical limits on how quickly black holes can grow once they’ve formed, but ones that are born more massive have a head start. It’s like planting a sapling, which takes less time to grow into a full-size tree than if you started with only a seed,” said Andy Goulding, research scholar in astrophysical sciences at Princeton University in New Jersey.
He is a coauthor on the Nature Astronomy paper and lead author of another paper on the UHZ1 galaxy published in September in The Astrophysical Journal Letters.
The team reporting its results in the Nature Astronomy paper had discovered that the distant black hole’s mass is similar to the entire mass of all of the stars within the galaxy that hosts it. The mass falls somewhere between that of 10 million and 100 million suns, judging by the brightness and energy of the X-rays emitted by it, the researchers said.
Potential black hole theory
Typically, black holes located at the centers of galaxies only have about 0.1% the mass of the stars within their host galaxy.
The unusual black hole could be an “Outsize Black Hole” that formed when a huge cloud of gas collapsed, as theorized in 2017 by Priyamvada Natarajan, a coauthor on both studies and the Joseph S. and Sophia S. Fruton professor of astronomy and professor of physics at Yale University in New Haven, Connecticut.
“We think that this is the first detection of an ‘Outsize Black Hole’ and the best evidence yet obtained that some black holes form from massive clouds of gas,” Natarajan said. “For the first time we are seeing a brief stage where a supermassive black hole weighs about as much as the stars in its galaxy, before it falls behind.”
Universe's oldest X-ray-spitting quasar could reveal how the biggest black holes were born
Robert Lea
Wed, November 8, 2023
An illustration showing a quasar powered by a feeding supermassive black hole.
Astronomers using NASA's James Webb Space Telescope (JWST) and Chandra X-ray Observatory have discovered the oldest and most distant X-ray-spitting quasar in the known universe, and it seems to be powered by the "seed" of an ancient supermassive black hole.
Quasars are the bright hearts of active galaxies, which are fueled by active supermassive black holes that cause infalling matter to emit intense thermal radiation as they feed. Quasars can be so bright across the entire electromagnetic spectrum that they often outshine the combined light from every star in the galaxy surrounding them.
This primordial quasar, designated UHZ1, was spotted in high-energy X-ray light emitted when the cosmos was no more than 450 million years old and has thus been traveling through the universe for around 13.7 billion years to reach us. As such, this quasar could be an example of a black hole "seed" in the early universe that helps reveal how supermassive black holes reached tremendous masses of millions, or even billions, of times that of the sun.
"It's thrilling to be able to reveal the presence of a supermassive black hole, in place at the center of a galaxy a mere 450 million years after the Big Bang," study co-author Priyamvada Natarajan, a professor of astronomy and physics at Yale University, said in a statement. "NASA's Chandra space telescope detected X-rays from this distant quasar, which harbors an outsized black hole in its center."
Related: James Webb telescope reveals the universe may have far fewer active black holes than we thought
The discovery of UHZ1 is detailed in a paper published in the journal Nature Astronomy.
Understanding how supermassive black holes got so huge
This image contains the most distant black hole ever detected made using X-rays from NASA's Chandra X-ray Observatory (purple) and infrared data from NASA's James Webb Space Telescope (red, green, blue).
Scientists theorize that supermassive black holes grew to such tremendous sizes by starting off as black hole seeds in the early universe and growing steadily by gorging on matter and merging with other black holes.
The question is, how big were these seeds to begin with? One variation of this theory suggests the early universe was packed with "light seeds" — black holes created when massive stars ran out of fuel for nuclear fusion and exploded in supernova blasts, collapsing under their own gravity.
However, this explanation doesn't give supermassive black holes enough time to reach masses equivalent to millions, let alone billions, of suns at the early times astronomers observe these behemoths in the infant universe.
One idea that would give supermassive black holes a "head start" on this process is if they started growing from "heavy seeds." Between 2006 and 2007, Natarajan developed a model suggesting that heavy black hole seeds could form in galaxies where star formation is suppressed.
These would be satellite galaxies located near the galaxies in the early universe that birthed the first stars. This model suggests that large disks of gas and dust in these satellite galaxies could collapse directly into black-hole-heavy seeds, instead of first birthing stars that eventually collapsed into black holes millions or billions of years later. These heavy-seed black hole satellite galaxies would then merge with the main star-forming galaxies nearby.
In 2017, Natarajan and her colleagues suggested that heavy black hole seed galaxies should be observable in the early universe thanks to their unique properties. In particular, the central black hole in a heavy-black-hole-seed galaxy would outweigh that galaxy's stars. This should be visible as X-ray quasars to the Chandra X-ray Observatory, as well as to the yet-to-be-launched JWST, Natarajan proposed in 2017.
Finding a heavy black hole seed
Now, six years later, the team's prediction bears fruit with the discovery of this distant X-ray quasar. UHZ1 was identified by a team led by Akos Bogdan, an astrophysicist at the Harvard and Smithsonian Center for Astrophysics, and Andy Goulding, an astrophysicist at Princeton, who combined recent data from the Chandra X-ray Observatory and JWST to peer behind galaxy Abell 2744.
"UHZ1 is the first candidate that matches all our predicted properties for this transient class of over-massive black hole galaxies," Natarajan said. "And now we're seeing compelling first evidence. This is an exciting intersection of topics, a culmination of all the things I have been working on."
Goulding thinks there are many more heavy-seed galaxies out there just waiting to be uncovered.
"UHZ1 may only be the tip of the iceberg," he said. "The JWST has opened a new window on the early universe. It will no doubt help us find more UHZ1s and ultimately understand if over-massive black holes were commonplace."
NASA's James Webb and X-ray telescopes found a primordial black hole growing in the early universe just after the Big Bang
Grace Eliza Goodwin,Jenny McGrath
Wed, November 8, 2023
NASA has discovered the most distant black hole ever, dating back nearly to the dawn of time.
Don't worry: the growing black hole is located 13.2 billion light-years away.
The supermassive black hole was detected in a rare state of infancy.
NASA has discovered the most distant black hole ever detected, capturing it growing in a stage of never-before-seen infancy near the dawn of time.
The space agency announced this week that it had combined X-ray data from the James Webb Space Telescope and the Chandra X-ray Observatory to reveal the presence of the primordial supermassive black hole after spotting a distant galaxy.
Thanks to its large mirror and infrared lens, JWST is able to detect distant stars and galaxies as far as 28 billion light years away.
Located 13.2 billion light-years away from Earth, the black hole dates back to a time when the universe was just 3% of its current age, about 470 million years after the Big Bang, NASA said in the press release.
Since light travels at a constant speed, and distant objects are billions of light-years away from us, we see those objects as they looked in the past.
That gives researchers the opportunity to see the early universe moments after it formed. This black hole is the latest in an impressive catalogue of record-breaking discoveries from JWST.
In its first week of operation, JWST found a 13.5 billion-year-old galaxy. It also detected another of the earliest black holes and picked up lots of details Hubble wasn't able to capture.
This black hole, in particular, was captured in a stage of life younger than any others scientists have discovered, at a point when it was still growing and its total mass was similar to that of its host galaxy, NASA said.
Compared to the mass of their host galaxies, supermassive black holes are usually far smaller — about a tenth of a percent the size, per NASA.
Scientists hope the discovery can help them learn how black holes like this were able to grow so big so soon after the dawn of time.
"There are physical limits on how quickly black holes can grow once they've formed, but ones that are born more massive have a head start. It's like planting a sapling, which takes less time to grow into a full-size tree than if you started with only a seed," Andy Goulding, a research scholar at Princeton University and co-author of the study, said in NASA's press release.
Laura Baisas
Tue, November 7, 2023
Astronomers found the most distant black hole ever detected in X-rays (in a galaxy dubbed UHZ1) using the Chandra X-Ray Observatory and the James Webb Space Telescope. X-ray emission is a telltale signature of a growing supermassive black hole. This result may explain how some of the first supermassive black holes in the universe formed. These images show the galaxy cluster Abell 2744 that UHZ1 is located behind, in X-rays from Chandra and infrared data from JWST, as well as close-ups of the black hole host galaxy UHZ1.
Astronomers have discovered the most distant supermassive black hole ever observed. They had the help of a “cosmic magnifying glass,” or gravitational lensing. This happens when a massive celestial body creates a large curvature of spacetime so that the path of light around it can be bent as if by a lens.
The black hole is located in the galaxy UHZ1 in the direction of the galaxy cluster Abell 2744. The galaxy cluster is about 13.2 billion-years-old. The team used NASA’s Chandra X-ray Observatory and the James Webb Space Telescope (JWST) to find the telltale signature of a growing black hole. It started to form only 470 million years after the big bang when the universe was only 3 percent of its current age of about 13.7 billion years-old. The galaxy is much more distant than the cluster itself, at 13.2 billion light-years from Earth.
Astronomers can tell that this black hole is so young because it is so giant. Black holes evaporate over time. Most black holes in galactic centers have a mass that is equal to roughly a tenth of the stars in their host galaxy, according to NASA. This early black hole is growing and as a mass that is on par with our entire galaxy. Astronomers have never witnessed a black hole at this stage before and studying it could help explain how some of the first supermassive black holes in the universe formed. The findings are detailed in a study published November 6 in the journal Nature Astronomy.
“We needed Webb to find this remarkably distant galaxy and Chandra to find its supermassive black hole,” study co-author and astronomer Akos Bogdan said in a statement. Bogdan is affiliated with the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.
“We also took advantage of a cosmic magnifying glass that boosted the amount of light we detected,” Bogman added. This magnifying effect is known as gravitational lensing. The team took X-ray observations with Chandra for two weeks. They saw intense, superheated X-ray emitting gas—a supermassive black hole’s trademark—from the galaxy. The light coming from the galaxy and the X-ray from the gas around the supermassive black hole were magnified by the hot gas and dark matter coming from the galaxy cluster. This effect was like a “cosmic magnifying glass” and it enhanced the infrared light signals that the JWST could detect and allowed Chandra to see the faint X-ray source.
“There are physical limits on how quickly black holes can grow once they’ve formed, but ones that are born more massive have a head start. It’s like planting a sapling, which takes less time to grow into a full-size tree than if you started with only a seed,” study co-author and Princeton University astronomer Andy Goulding said in a statement.
Observing this phenomenon could help astronomers answer how some supermassive black holes can hit enormous masses so soon after the explosion of energy from the big bang. There are two opposed theories for the origin of these supermassive black holes–light seed versus heavy seed. The light seed theory says that a star will collapse into a stellar mass black hole and then grow into a supermassive black hole over time. In the heavy seed theory, a large cloud of gas–not an individual star–collapses and condenses to form the supermassive black hole. This newly discovered black hole could confirm the heavy seed theory.
“We think that this is the first detection of an ‘Outsize Black Hole’ and the best evidence yet obtained that some black holes form from massive clouds of gas,” study co-author and Yale University theoretical astrophysicist Priyamvada Natarajan said in a statement. “For the first time we are seeing a brief stage where a supermassive black hole weighs about as much as the stars in its galaxy, before it falls behind.”
The team plans to use this and more data coming in from the JWST and other space telescopes to create a better picture of the early universe.
This supermassive black hole is the most distant ever seen in X-rays
Keith Cooper
Tue, November 7, 2023
Shown is the galaxy cluster Abell 2744, with the distant galaxy UHZ1 that formed just 470 million years after the Big Bang. It was imaged by the Chandra X-Ray Observatory and the James Webb Space Telescope (inset). The blue glow is X-rays from the hot gas in the cluster, and inset, from hot gas around the black hole at the center of UHZ1.More
A newly found black hole is shattering records, revealing new things about how such objects formed.
Two space telescopes paired up to examine a giant black hole that has a mass approximately equal to the galaxy that hosts it. It's an early starter: the galaxy existed just 470 million years after the Big Bang that formed our universe about 13.8 billion years ago. The existence of this black hole is, therefore, a huge clue as to how supermassive black holes at the center of galaxies form.
Black holes are very dense objects with such intense gravity that even light cannot escape, if it strays too close. The new black hole is a record breaker: the most distant yet observed in X-rays. As such, the observations from NASA's James Webb Space Telescope (Webb or JWST) and the agency's Chandra X-ray Observatory capture the black hole in a stage of its growth never before seen.
Related: Black holes: Everything you need to know
The JWST first spotted the feeble light of the early galaxy, called UHZ1. The mass of the galaxy is approximately 140 million times the mass of the sun. JWST saw the galaxy due to gravitational lensing, when the gravity of a massive foreground galaxy cluster, Abell 2744, amplified the light of UHZ1.
When Chandra followed up on UHZ1 and observed it for two weeks, it detected powerful X-rays coming from a disk of gas swirling around in the gravitational field of a supermassive black hole at the core of the distant galaxy.
"We needed Webb to find this remarkably distant galaxy, and Chandra to find its supermassive black hole," Ákos Bogdán of the Harvard–Smithsonian Center for Astrophysics, said in a statement Monday (Nov. 6). Bogdán is the lead author of a paper in Nature Astronomy describing the X-ray observations and signature of the black hole, mainly based on Chandra but also including Webb data.
Judging by the brightness and intensity of the X-rays, which are connected to the strength of the black hole's gravity, the black hole has a mass of the order of tens of millions to hundreds of millions of solar masses, equivalent to the mass of its host galaxy.
Related: Star-birthing galaxies can hide supermassive black holes behind walls of dust
The Chandra X-Ray Observatory and its upper stage are seen in this photo taken by an astronaut on the space shuttle Columbia just after the space telescope was deployed in orbit on July 23, 1999.
UHZ1 is still fairly small for a galaxy, however. Models of galaxy formation describe how they begin small and then grow through mergers, either with other galaxies or gigantic intergalactic gas clouds. What isn't understood very well is how their supermassive black holes form.
There are two candidate theories to explain their formation. One is that they formed through rapid mergers of stellar-mass black holes produced by exploding stars. The other possibility is that supermassive black holes formed directly from a collapsing gas cloud that had a mass between 10,000 and 100,000 times that of the sun.
The new research suggests the newfound black hole was born large, with an estimated mass of roughly 10 million and 100 million suns when calculating the X-rays' brightness and energy.
"There are physical limits on how quickly black holes can grow once they’ve formed, but ones that are born more massive have a head start. It’s like planting a sapling, which takes less time to grow into a full-size tree than if you started with only a seed," said Andy Goulding of Princeton University. Goulding is lead author of a Sept. 22 paper in The Astrophysical Journal Letters that reports the galaxy’s distance and mass, and co-author on the new Nature Astronomy paper.
The brightness and energy of the X-rays are in the realm predicted in calculations by theoretical astrophysicist Priyamvada Natarajan of Yale University, which lead to the creation of "outsize black holes" that form directly from gas cloud collapse.
"We think that this is the first detection of an outsize black hole, and the best evidence yet obtained that some black holes form from massive clouds of gas," Natarajan said in the same statement. "For the first time, we are seeing a brief stage where a supermassive black hole weighs about as much as the stars in its galaxy, before it falls behind."
In most modern galaxies, the supermassive black hole amounts to only a tenth of the mass of its host galaxy. The mass of the black hole is also correlated to the stellar mass of a spiral galaxy's central bulge, or the overall mass of an elliptical galaxy. By witnessing an active black hole in this stage of growth, the observations could shed light on how this correlation occurs. Either way, UHZ1 certainly has a lot of growing to do to outpace the growth of its black hole.
Telescopes spot the oldest and most distant black hole formed after the big bang
Ashley Strickland, CNN
Tue, November 7, 2023
NASA/ESA/CSA/STScI/CXC/SAO/Ákos Bogdán/L. Frattare & K. Arcand
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Two powerful NASA telescopes have detected the oldest and most distant black hole ever found.
Data captured via energetic X-rays by the Chandra X-ray Observatory and James Webb Space Telescope has helped astronomers spot the signature of a growing black hole within the early universe just 470 million years after the big bang, which occurred 13.8 billion years ago.
The discovery, described in a study published Monday in the journal Nature Astronomy, may help astronomers piece together how some of the first supermassive black holes formed in the cosmos.
“We needed Webb to find this remarkably distant galaxy and Chandra to find its supermassive black hole,” said lead study author Akos Bogdan, in a statement. “We also took advantage of a cosmic magnifying glass that boosted the amount of light we detected.” Bogdan is an astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.
He was referring to an effect called gravitational lensing, which occurs when closer objects — in this case a galactic cluster — act like a magnifying glass for distant objects. Gravity essentially warps and amplifies the light of distant galaxies in the background of whatever is doing the magnifying, enabling observations of otherwise invisible celestial features.
Astronomers detected the black hole in a galaxy called UHZ1. At first glance, the galaxy appeared in the same direction as a cluster of galaxies known as Abell 2744, which is located about 3.5 billion light-years from Earth. But data collected by the Webb telescope showed that UHZ1 is actually much farther away and located beyond the cluster at 13.2 billion light-years from Earth.
A light-year, equivalent to 5.88 trillion miles, is how far a beam of light travels in a year. Given the distance between Earth and the objects from the early days of the universe, when telescopes like Webb observe this light, it’s effectively like looking into the past.
The team used the Chandra Observatory to detect superheated gas releasing X-rays within UHZ1, the telltale sign of a supermassive black hole growing in size.
The detection was made possible by the Abell cluster of galaxies, which intensified the light of the UHZ1 galaxy and the X-rays released by the black hole by a factor of four.
Decoding a cosmic mystery
Astronomers think the discovery will help them to better understand how supermassive black holes appeared and reached their monstrous masses so soon after the beginning of the universe.
The researchers want to know whether the giant celestial objects formed when massive clouds of gas collapsed or if they resulted from the explosions of the very first massive stars.
“There are physical limits on how quickly black holes can grow once they’ve formed, but ones that are born more massive have a head start. It’s like planting a sapling, which takes less time to grow into a full-size tree than if you started with only a seed,” said Andy Goulding, research scholar in astrophysical sciences at Princeton University in New Jersey.
He is a coauthor on the Nature Astronomy paper and lead author of another paper on the UHZ1 galaxy published in September in The Astrophysical Journal Letters.
The team reporting its results in the Nature Astronomy paper had discovered that the distant black hole’s mass is similar to the entire mass of all of the stars within the galaxy that hosts it. The mass falls somewhere between that of 10 million and 100 million suns, judging by the brightness and energy of the X-rays emitted by it, the researchers said.
Potential black hole theory
Typically, black holes located at the centers of galaxies only have about 0.1% the mass of the stars within their host galaxy.
The unusual black hole could be an “Outsize Black Hole” that formed when a huge cloud of gas collapsed, as theorized in 2017 by Priyamvada Natarajan, a coauthor on both studies and the Joseph S. and Sophia S. Fruton professor of astronomy and professor of physics at Yale University in New Haven, Connecticut.
“We think that this is the first detection of an ‘Outsize Black Hole’ and the best evidence yet obtained that some black holes form from massive clouds of gas,” Natarajan said. “For the first time we are seeing a brief stage where a supermassive black hole weighs about as much as the stars in its galaxy, before it falls behind.”
Universe's oldest X-ray-spitting quasar could reveal how the biggest black holes were born
Robert Lea
Wed, November 8, 2023
An illustration showing a quasar powered by a feeding supermassive black hole.
Astronomers using NASA's James Webb Space Telescope (JWST) and Chandra X-ray Observatory have discovered the oldest and most distant X-ray-spitting quasar in the known universe, and it seems to be powered by the "seed" of an ancient supermassive black hole.
Quasars are the bright hearts of active galaxies, which are fueled by active supermassive black holes that cause infalling matter to emit intense thermal radiation as they feed. Quasars can be so bright across the entire electromagnetic spectrum that they often outshine the combined light from every star in the galaxy surrounding them.
This primordial quasar, designated UHZ1, was spotted in high-energy X-ray light emitted when the cosmos was no more than 450 million years old and has thus been traveling through the universe for around 13.7 billion years to reach us. As such, this quasar could be an example of a black hole "seed" in the early universe that helps reveal how supermassive black holes reached tremendous masses of millions, or even billions, of times that of the sun.
"It's thrilling to be able to reveal the presence of a supermassive black hole, in place at the center of a galaxy a mere 450 million years after the Big Bang," study co-author Priyamvada Natarajan, a professor of astronomy and physics at Yale University, said in a statement. "NASA's Chandra space telescope detected X-rays from this distant quasar, which harbors an outsized black hole in its center."
Related: James Webb telescope reveals the universe may have far fewer active black holes than we thought
The discovery of UHZ1 is detailed in a paper published in the journal Nature Astronomy.
Understanding how supermassive black holes got so huge
This image contains the most distant black hole ever detected made using X-rays from NASA's Chandra X-ray Observatory (purple) and infrared data from NASA's James Webb Space Telescope (red, green, blue).
Scientists theorize that supermassive black holes grew to such tremendous sizes by starting off as black hole seeds in the early universe and growing steadily by gorging on matter and merging with other black holes.
The question is, how big were these seeds to begin with? One variation of this theory suggests the early universe was packed with "light seeds" — black holes created when massive stars ran out of fuel for nuclear fusion and exploded in supernova blasts, collapsing under their own gravity.
However, this explanation doesn't give supermassive black holes enough time to reach masses equivalent to millions, let alone billions, of suns at the early times astronomers observe these behemoths in the infant universe.
One idea that would give supermassive black holes a "head start" on this process is if they started growing from "heavy seeds." Between 2006 and 2007, Natarajan developed a model suggesting that heavy black hole seeds could form in galaxies where star formation is suppressed.
These would be satellite galaxies located near the galaxies in the early universe that birthed the first stars. This model suggests that large disks of gas and dust in these satellite galaxies could collapse directly into black-hole-heavy seeds, instead of first birthing stars that eventually collapsed into black holes millions or billions of years later. These heavy-seed black hole satellite galaxies would then merge with the main star-forming galaxies nearby.
In 2017, Natarajan and her colleagues suggested that heavy black hole seed galaxies should be observable in the early universe thanks to their unique properties. In particular, the central black hole in a heavy-black-hole-seed galaxy would outweigh that galaxy's stars. This should be visible as X-ray quasars to the Chandra X-ray Observatory, as well as to the yet-to-be-launched JWST, Natarajan proposed in 2017.
Finding a heavy black hole seed
Now, six years later, the team's prediction bears fruit with the discovery of this distant X-ray quasar. UHZ1 was identified by a team led by Akos Bogdan, an astrophysicist at the Harvard and Smithsonian Center for Astrophysics, and Andy Goulding, an astrophysicist at Princeton, who combined recent data from the Chandra X-ray Observatory and JWST to peer behind galaxy Abell 2744.
"UHZ1 is the first candidate that matches all our predicted properties for this transient class of over-massive black hole galaxies," Natarajan said. "And now we're seeing compelling first evidence. This is an exciting intersection of topics, a culmination of all the things I have been working on."
Goulding thinks there are many more heavy-seed galaxies out there just waiting to be uncovered.
"UHZ1 may only be the tip of the iceberg," he said. "The JWST has opened a new window on the early universe. It will no doubt help us find more UHZ1s and ultimately understand if over-massive black holes were commonplace."
NASA's James Webb and X-ray telescopes found a primordial black hole growing in the early universe just after the Big Bang
Grace Eliza Goodwin,Jenny McGrath
Wed, November 8, 2023
NASA has discovered the most distant black hole ever, dating back nearly to the dawn of time.
Don't worry: the growing black hole is located 13.2 billion light-years away.
The supermassive black hole was detected in a rare state of infancy.
NASA has discovered the most distant black hole ever detected, capturing it growing in a stage of never-before-seen infancy near the dawn of time.
The space agency announced this week that it had combined X-ray data from the James Webb Space Telescope and the Chandra X-ray Observatory to reveal the presence of the primordial supermassive black hole after spotting a distant galaxy.
Thanks to its large mirror and infrared lens, JWST is able to detect distant stars and galaxies as far as 28 billion light years away.
Located 13.2 billion light-years away from Earth, the black hole dates back to a time when the universe was just 3% of its current age, about 470 million years after the Big Bang, NASA said in the press release.
Since light travels at a constant speed, and distant objects are billions of light-years away from us, we see those objects as they looked in the past.
That gives researchers the opportunity to see the early universe moments after it formed. This black hole is the latest in an impressive catalogue of record-breaking discoveries from JWST.
In its first week of operation, JWST found a 13.5 billion-year-old galaxy. It also detected another of the earliest black holes and picked up lots of details Hubble wasn't able to capture.
This black hole, in particular, was captured in a stage of life younger than any others scientists have discovered, at a point when it was still growing and its total mass was similar to that of its host galaxy, NASA said.
Compared to the mass of their host galaxies, supermassive black holes are usually far smaller — about a tenth of a percent the size, per NASA.
Scientists hope the discovery can help them learn how black holes like this were able to grow so big so soon after the dawn of time.
"There are physical limits on how quickly black holes can grow once they've formed, but ones that are born more massive have a head start. It's like planting a sapling, which takes less time to grow into a full-size tree than if you started with only a seed," Andy Goulding, a research scholar at Princeton University and co-author of the study, said in NASA's press release.
Saturn’s awe-inspiring rings will ‘disappear’ in 2025: Here’s why
Bill Shannon
Tue, November 7, 2023
(WTAJ) — One of the most awe-inspiring sights in our solar system, Saturn, is about to lose its iconic look.
Well, sort of.
As Saturn dances in the night sky, it tilts on an axis, much like Earth. The planet takes 29.4 Earth years to complete an orbit around the sun. It rotates quickly, though, making a day on Saturn only 10.7 Earth hours, according to NASA.
This June 2023 image provided by the Space Telescope Science Institute shows the planet Saturn and three of its moons, from left, Enceladus, Tethys and Dione, captured by the James Webb Space Telescope. In infrared, the planet appears dark because sunlight is absorbed by methane in the atmosphere. (NASA, ESA, CSA, JWST Saturn Team via AP)More
While it’s known to scientists that Saturn’s rings are slowly (as in over the next millions of years) being pulled into the planet’s atmosphere, 2025 will be a bit different.
What’s happening to Saturn’s rings?
Saturn is transitioning and as its tilt changes, it will align the edge of its rings directly with Earth. Think of it as trying to see a piece of paper edge-on from the opposite endzone of a football field.
Fear not, though. Saturn will continue its celestial dance and by the year 2032, it’s predicted the transition will give us a marvelous look at the underside of its rings, according to Space.com.
Northern lights could ramp up next year, and so could these strange occurrences
This event happens roughly every 15 years, according to NASA. We’ll cross Saturn’s ring plane on March 23, 2025, specifically, but there can be anywhere from one to three crossings per half-orbit of Saturn.
While Saturn’s rings will seemingly “disappear” in two years, we won’t have an entirely “ringless” view until the “triple passage” in 2038 and 2039. According to NASA, on October 15, 2038, and April 1 and July 9, 2039, we’ll experience “favorable ring plane crossings” that will make Saturn appear even more ringless.
NASA predicts large asteroid impact could be in Earth’s future
While we won’t be able to see Saturn’s rings in 2025, this cosmic event should offer a great view of many of Saturn’s 146 moons.
Speaking of moons, scientists with NASA believe the mass of moons orbiting the planet is what causes the tilt of Saturn to alter and it will continue to happen over the next billion years.
Saturn's rings will disappear from view for a time. This is why and when
Manahil Ahmad, NorthJersey.com
Wed, November 8, 2023
If you love looking at the stunning rings of Saturn, here's a heads-up: They're going to vanish from our view briefly.
According to reports from the International Federation of Learning in Science, this rare occurrence is expected to take place in 2025. As Saturn embarks on its 30-year journey around the sun, a unique alignment will briefly obscure our unobstructed view of these enigmatic rings.
Saturn's rings are beautiful bands of ice and rock that surround the planet. They're made up of tiny pieces and huge boulders that move around the planet, creating this famous ring system. Scientists think these rings might be leftovers from a moon that got too close to Saturn and broke apart due to the planet's strong gravity.
The thing is, Saturn's rings don't always look the same. Because of the way Saturn moves, the angle at which we see the rings changes. This intriguing phenomenon occurs roughly every 15 years due to the unique orbital dynamics of the Saturnian system. As the planet transitions through its orbit, the rings align with our line of sight in such a way that they seem to disappear.
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It is essential to note that while Saturn's rings may briefly vanish from sight, this is a natural occurrence, and they will reappear as Saturn's position in its orbit changes. This disappearance provides scientists with an opportunity to learn more about the composition and structure of the rings when they are seen edge-on, offering a fresh perspective on these cosmic wonders.
So, get ready to say goodbye temporarily to Saturn's rings in 2025, and be prepared to welcome them back with open arms. It's a reminder that the universe is full of surprises and keeps us in awe of its beauty.
This article originally appeared on NorthJersey.com: Saturn rings to disappear from view briefly in 2025
Evidence of alien life may exist in the fractures of icy moons around Jupiter and Saturn
Robert Lea
Wed, November 8, 2023
Dual image showing saturn with a transiting moon on the left, and a grey planetary body on the right.
Scientists are investigating specific geological features on the largest moons of both Jupiter and Saturn that could be ideal spots for the emergence of life elsewhere in the solar system.
The team, led by researchers from the University of Hawaii at Mānoa, looked at what are called "strike-slip faults" on the Jovian moon, Ganymede — the solar system’s largest moon, bigger even than the planet Mercury — and Saturn's moon, Titan. Faults like these happen when fault walls move past each other horizontally, either to the left or the right, with a famous example here on Earth being the San Andreas fault. It's sort of like a giant crack, rift, or certain type of crevice in the ground.
Such seismic features are generated on these icy moons, scientists believe, when these bodies orbit their parent gas-giant planets. The planets' immense gravitational influences generate tidal forces that squash and squeeze the moons, inevitably flexing the natural satellites' surfaces. Plus, these tidal forces aren’t very consistent because the orbits of both moons are elliptical, meaning they are sometimes closer to Saturn or Jupiter. Other times, they're much farther away. That, in turn, leads to even stronger tidal forces.
"We are interested in studying shear deformation on icy moons because that type of faulting can facilitate the exchange of surface and subsurface materials through shear heating processes, potentially creating environments conducive for the emergence of life," Liliane Burkhard, lead author of the research and a scientists at the Hawaii Institute of Geophysics and Planetology, said in a statement.
Related: NASA’s Juno probe detects organic compounds on huge Jupiter moon Ganymede
Strike-slip faults on Titan
Saturn’s moon, Titan, has surface temperatures of around minus 290 degrees Fahrenheit (minus 179 degrees Celsius). This is incredibly cold — cold enough that the water of this moon actually plays the role of rock. It can crack, deform and, ultimately, form faults.
During its flybys of Titan, NASA’s Cassini spacecraft was able to determine that this moon of Saturn may have liquid water oceans tens of miles beneath its thick shell of ice. Additionally, Titan is the only solar system moon with a dense, Earth-like atmosphere, meaning it has a similar hydrological cycle with methane clouds, rain and liquid flowing across the surface to fill lakes and seas. For this reason, Titan is already considered one of just a few bodies in our solar system that could support life — as we know it, at least.
When the NASA Dragonfly mission (which launches in 2027) arrives at Titan in 2034, it will send a rotorcraft lander to fly across the frigid surface of this moon in an effort to hunt for those potential biological signs. That doesn't exactly mean it'll search for bug-eyed aliens, however. At the very least, the team hopes the lander will detect the chemical building blocks of life we're familiar with.
The Dragonfly mission is initially set to land at the Selk crater area on Titan, a region that is also of interest to Burkhard and the team. This is because when calculating the stress exerted on Titan’s surface as a result of tidal forces, the researchers weren't only focused on whether there might be signs of extraterrestrial life on the ground. They also explored the chance that the Selk crater region could be subjected to shear deformation to figure out whether it's a safe landing site option for Dragonfly in the first place.
"While our prior research indicated that certain areas on Titan might currently undergo deformation due to tidal stresses, the Selk crater area would need to host very high pore fluid pressures and a low crustal coefficient of friction for shear failure, which seems improbable," said Burkhard. "Consequently, it’s safe to infer that Dragonfly won’t be landing in a strike-slip ditch!"
Three images show strike-slip faults at the San Andreas Fault (a) on Ganymede (b) and on Titan
Burkhard and colleagues also looked at the geology of the Jovian moon, Ganymede, to investigate the icy body’s history of tidal stress. In particular, the team looked at a bright region in the northwest of Ganymede called Philus Sulcus, which is composed of parallel sets of fractures.
The researchers basically looked at available high-resolution observations of the area to find that there were different degrees of tectonic deformation in bands of light terrain that cross over each other. The cross-cutting nature of these bands indicated to Burkhard and colleagues the existence of three distinct eras of geological activity — ancient, intermediate, and young.
"I investigated strike-slip faulting features in intermediate-aged terrain, and they correspond in slip direction to the predictions from modeling stresses of a higher past eccentricity," said Burkhard. "Ganymede could have undergone a period where its orbit was much more elliptical than it is today."
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When investigating other parts of Philus Sulcus, the team found the direction of slip features to have different alignments. This implies these features may have been generated by processes other than high tidal stress. "So, Ganymede has had a tidal 'midlife crisis,' but its youngest 'crisis' remains enigmatic," Burkhard added.
The geologic investigations undertaken by this team and others are vital for informing the missions of spacecraft that aim to explore solar system moons like Titan and Ganymede. said Burkhard.
“Missions such as Dragonfly, Europa Clipper, and ESA’s JUICE will further constrain our modeling approach and can help pinpoint the most interesting locations for lander exploration and possibly for gaining access to the interior ocean of icy moons,” Burkhard concluded.
The team’s research is published across two papers in the journal Icarus.
The Juno spacecraft spotted evidence of a salty ocean on Jupiter's biggest moon
Briley Lewis
Wed, November 8, 2023
Juno observed Jupiter and three of its moons, including Ganymede, furthest to the left.
NASA’s Juno spacecraft has been exploring Jupiter since it arrived at the planet in 2016. In recent years, the mission has turned its attention to the gas giant’s many moons, including the hellish volcanic world Io and the ice ball Europa. Now, in research published in Nature Astronomy, the Juno team revealed new photos of Jupiter’s largest moon, Ganymede, which show evidence of salts and organic compounds. These materials are likely the residue of salty sea water from an underground ocean that bubbled up to the frozen surface of Ganymede. And, excitingly, a salty ocean indicates conditions there might be conducive to life.
Ganymede is a particularly weird place. Not only is it Jupiter’s most massive satellite, it’s the biggest moon in the whole solar system—it’s even larger than the planet Mercury. It also is the only moon to have its own magnetic field, generated from a molten metal core deep in its interior. Like other icy worlds of the outer solar system, such as Europa or possibly Pluto, Ganymede probably has an ocean lurking under its icy crust. Some studies suggest multiple seas, stacked together in a layer cake of ice sheets and oceans, hide underground.
“Because Ganymede is so big, its interior structure is more complicated” than that of smaller worlds, explains University of Arizona geologist Adeene Denton, who is not affiliated with the new work. She notes that the moon’s massive size means there’s a lot of space for interesting molecules to mix about. But that also means they’re tricky to spot, because material must cover a large distance to get to the surface where our spacecraft can see them.
Juno finally passed close enough to Ganymede—within 650 miles, less than the distance from New York City to Chicago—to take a close look at the chemicals on its surface using its Jovian InfraRed Auroral Mapper (JIRAM). This incredible instrument tracked the composition of Ganymede’s surface in great detail, noting features as small as 1 kilometer wide. If JIRAM were looking at New York City, it would be able to map Manhattan in ten-block chunks.
Importantly, material on the surface of Ganymede might tell us about the water hiding below. If there are salts above, the subsurface ocean might have that same brine. Oceans, including the ones on Earth, acquire their salt from chemical interactions where liquid water touches a rocky mantle. This kind of exchange is “one of the conditions necessary for habitability,” says lead author Federico Tosi, research scientist at the National Institute for Astrophysics in Rome, Italy.
However, other current research suggests that Ganymede doesn’t have a liquid water layer directly touching its mantle. Instead, icy crusts separate the ocean from the rock. But because the team did see these salts in the JIRAM data, it suggests they were touching at one point in the past, if not now. “This testifies to an era when the ocean must have been in direct contact with the rocky mantle,” explains Tosi.
As for the organic chemicals that Juno detected, the team still isn’t completely sure what flavor of compound they are. They’re leaning towards aliphatic aldehydes, a type of molecule found elsewhere in the solar system that’s known as an intermediate step necessary to build more complex amino acids. These usually indicate liquid water and a rocky mantle are interacting. This definitely isn’t a detection of life, but it’s interesting for the possibility of life lurking in Ganymede’s hidden oceans. “The presence of organic compounds does not imply the presence of life forms,” says Tosi. “But the opposite is true: life requires the presence of some categories of organic compounds.”
Unfortunately, Juno won’t have a chance to swing by Ganymede again to search for more salty shores—instead, it’s headed toward the explosive Io. The probe’s most recent survey of these minerals was a “a unique opportunity to take a close look at this satellite,” Tosi says. We won’t have to wait too much longer, though, for a second visit. In about ten years, he adds, we’ll get another chance to explore these salty waters with the ESA JUICE mission, “which is expected to achieve complete and unprecedented coverage of Ganymede.”
Just How Many Galaxies Are in the Universe?
Craig Freudenrich, Ph.D.
Wed, November 8, 2023
The Andromeda galaxy, pictured here, is just one of many in the known universe.
2008 HowStuffWorks
Galaxy Types
Galaxies come in a variety of sizes and shapes. They can have as few as 10 million stars or as many as 10 trillion (the Milky Way has about 200 billion stars). In 1936, Edwin Hubble classified galaxy shapes in the Hubble Sequence.
Elliptical Galaxy
These have a faint, rounded shape, but they're devoid of gas and dust, with no visible bright stars or spiral patterns. They also don't have galactic disks, which we'll learn about below.
Their classification varies from E0 (circular) to E7 (most elliptical). Elliptical galaxies probably comprise about 60 percent of the galaxies in the universe.
They show wide variation in size — most are small (about 1 percent the diameter of the Milky Way), but some are about five times larger than the diameter of the Milky Way.
Spiral Galaxy
The Milky Way is one of the larger spiral galaxies. They're bright and distinctly disk-shaped, with hot gas, dust and bright stars in the spiral arms. Because spiral galaxies are bright, they make up most of the visible galaxies, but they're thought to make up only about 20 percent of the galaxies in the universe.
Spiral galaxies are subdivided into these categories:
S0: Little gas and dust, with no bright spiral arms and few bright stars
Normal spiral: Obvious disk shape with bright centers and well-defined spiral arms. Sa galaxies have large nuclear bulges and tightly wound spiral arms, while Sc galaxies have small bulges and loosely wound arms.
Barred spiral: Obvious disk shape with elongated, bright centers and well-defined spiral arms. SBa galaxies have large nuclear bulges and tightly wound spiral arms, while SBc galaxies have small bulges and loosely wound arms (the Milky Way may be a SBc galaxy).
Irregular Galaxy
These are small, faint galaxies with large clouds of gas and dust, but no spiral arms or bright centers. Irregular galaxies contain a mixture of old and new stars and tend to be small, about 1 percent to 25 percent of the Milky Way's diameter.
Galaxy Parts
Spiral galaxies have the most complex structures. Here's a view of the Milky Way as it would appear from the outside.
2008 HowStuffWorks
Galactic Disk
Most of the Milky Way's more than 200 billion stars are located here. The disk itself is broken up into these parts:
Nucleus: The center of the disk
Bulge: The area around the nucleus, including the immediate areas above and below the plane of the disk
Spiral arms: These extend outward from the center; our solar system is located in one of the spiral arms of the Milky Way.
Globular Clusters
A few hundred of these are scattered above and below the disk. The stars here are much older than those in the galactic disk.
Halo
A halo is a large, dim, region that surrounds the entire galaxy. It's made of hot gas and possibly dark matter.
Gravity
All of these components orbit the nucleus and are held together by gravity. Because gravity depends upon mass, you might think that most of a galaxy's mass would lie in the galactic disk or near the center of the disk.
However, by studying the rotation curves of the Milky Way and other galaxies, astronomers have concluded that most of the mass lies in the outer portions of the galaxy (like the halo), where there is little light given off from stars or gases.
History of Galaxies
Let's look at the history of galaxies in astronomy.
Early Observations
The Greeks coined the term "galaxies kuklos" for "milky circle" when describing the Milky Way. The Milky Way was a faint band of light, but they had no idea what it was composed of.
When Galileo looked at the Milky Way with the first telescope, he determined that it was made up of numerous stars.
We've known for centuries that our solar system was located within the Milky Way because the Milky Way surrounds us. We can see it throughout the year in all parts of the sky, but it's brighter during the summer, when we're looking at the center of the galaxy. However, to astronomers in the 18th century and earlier, it wasn't clear that the Milky Way was a galaxy and not just a distribution of stars.
18th-century Findings
In the late 18th century, astronomers William and Caroline Herschel mapped the distances to stars in many directions. They determined that the Milky Way was a disk-like cloud of stars with the sun near the center.
In 1781, Charles Messier cataloged various nebulae (faint patches of light) throughout the sky and classified several of them as spiral nebulae.
20th-century Discoveries
In the early 20th century, astronomer Harlow Shapely measured the distributions and locations of globular star clusters. He determined that the center of the Milky Way was 28,000 light-years from Earth, near the constellations of Sagittarius and Scorpio, and that the center was a bulge, rather than a flat area.
Shapely later argued that the spiral nebulae discovered by Messier were "island universes" or galaxies (retaining the Greek wording). However, another astronomer named Heber Curtis argued that spiral nebulae were merely part of the Milky Way.
The debate raged on for years because astronomers needed larger, more powerful, telescopes to resolve the details.
21st-century Innovations
In 1924, Edwin Hubble settled the debate. He used a large telescope with a 100-inch diameter — larger than ones that were available to Shapely and Curtis — at Mount Wilson in California and resolved that the spiral nebulae had structure and stars called Cepheid variables, like those in the Milky Way. (These stars change their brightness regularly, and the luminosity is directly related to the period of their brightness cycle.)
Hubble used the light curves of the Cepheid variables to measure their distances from Earth and found that they were much farther away than the known limits of the Milky Way. Therefore, these spiral nebulae were indeed other galaxies outside our own.
There are still many mysteries surrounding galaxy formation, but on the next page we'll explain some of the best theories about it.
Light-years Away
Galaxies are far apart. The Andromeda galaxy, which is also called M31 (Messier object #31), is the closest galaxy to us — 2.2 million light years away. Astronomers usually measure intergalactic distances in terms of megaparsecs:
one parsec = 3.26 light years
one million parsecs = one megaparsec
one megaparsec (Mpc) = 3.26 million light years
The farthest visible galaxies are approximately 3,000 Mpc away, or about 10 billion light years.
2008 HowStuffWorks
Galaxy Formation
We really don't know how various galaxies formed and took the many shapes that we see today. But we do have some ideas about their origins and evolution.
Shortly after the big bang about 14 billion years ago, collapsing gas and dust clouds might have lead to the formation of galaxies.
Interactions between galaxies, specifically collisions between galaxies, play an important role in their evolution.
Let's look at the period of galaxy formation.
Edwin Hubble's observations, and subsequent Hubble Law (which we'll in a moment), led to the idea that the universe is expanding. We can estimate the age of the universe based on the rate of expansion.
Because some galaxies are billions of light years away from us, we can discern that they formed fairly soon after the big bang (as you look deeper into space, you see further back in time).
Most galaxies formed early, but data from NASA's Galaxy Explorer (GALEX) telescope indicate that some new galaxies have formed relatively recently — "recently" meaning within the past few billion years, whereas early galaxies formed over 10 billion years ago.
Most theories about the early universe make two assumptions:
It was filled with hydrogen and helium.
Some areas were slightly denser than others.
Protogalactic Clouds
From these assumptions, astronomers believe that the denser areas slowed the expansion slightly, allowing gas to accumulate in small protogalactic clouds. In these clouds, gravity caused the gas and dust to collapse and form stars.
These stars burned out quickly and became globular clusters, but gravity continued to collapse the clouds. As the clouds collapsed, they formed rotating disks.
The rotating disks attracted more gas and dust with gravity and formed galactic disks. Inside the galactic disk, new stars formed. What remained on the outskirts of the original cloud were globular clusters and the halo composed of gas, dust and dark matter.
Two factors from this process might account for the differences between elliptical and spiral galaxies:
Angular momentum (degree of spin): Protogalactic clouds with more angular momentum could spin faster and from spiral disks. Slow-spinning clouds could have formed elliptical galaxies.
Cooling: High-density protogalactic clouds cooled faster, using up all the gas and dust in forming stars and leaving none for making a galactic disk (this is why elliptical galaxies don't have disks). Low-density protogalactic clouds cool more slowly, leaving gas and dust for disk formation (like in spiral galaxies).
2008 HowStuffWorks
When Galaxies Collide
Galaxies do not act alone. The distances between galaxies do seem large, but the diameters of galaxies are also large.
Compared to stars, galaxies are relatively close to one another. They can interact and, more importantly, collide. When galaxies collide, they actually pass through one another — the stars inside don't run into one another because of the enormous interstellar distances.
But collisions do tend to distort a galaxy's shape. Computer models show that collisions between spiral galaxies tend to make elliptical ones (so, spiral galaxies probably haven't been involved in any collisions). Scientists estimate that as many as half of all galaxies have been involved in some sort of collision.
Gravitational interactions between colliding galaxies could cause several things:
New waves of star formation
Supernovae
Stellar collapses that form the black holes or supermassive black holes in active galaxies
So, do galaxies just float around in space or does some unseen force regulate their movement? And what happens when they run into each other?
2008 HowStuffWorks
Galaxy Distribution
Galaxies aren't randomly distributed throughout the universe; they tend to exist in galactic clusters. The galaxies in these clusters are bound together gravitationally and influence one another.
Rich clusters contain 1,000 or more galaxies. The Virgo supercluster, for example, includes more than 2,500 galaxies and is located about 55 million light-years from Earth.
Poor clusters contain less than 1,000 galaxies. The Milky Way and the Andromeda galaxy (M31) are the major members of the Local Group, which contains 50 galaxies.
When astronomers Margaret Geller and Emilio E. Falco plotted the positions of galaxies and galactic clusters in the universe, it became clear that galactic clusters and superclusters are not randomly distributed.
They're actually clumped together in walls (long filaments) interspersed with voids, which gives the universe a cobweb-like structure.
The Intergalactic Medium
The intergalactic medium — the space between galaxies and clusters of galaxies — is not entirely empty. We don't know the exact nature of the intergalactic medium, but it probably contains a relatively small density of gas.
Most of the intergalactic medium is cold (about 2 degrees Kelvin), but X-ray observations suggest that some areas of it are hot (millions of degrees Kelvin) and rich in metals.
One of the active areas of astronomical research today is directed at determining the nature of the intergalactic medium — it may help us figure out exactly how the universe began and how galaxies form and evolve.
Hubble's Law
Let's look at one final property concerning galaxies and their distributions. For his measurements of galactic distances, Edwin Hubble studied the spectra of light that galaxies emit.
In all cases, he noted that the spectra were Doppler-shifted to the red end of the spectrum. This indicates that the object is moving away from us.
Hubble noticed that, no matter where he looked, galaxies were moving away from us. And the farther the galaxy, the faster it was moving away. In 1929, Hubble published a graph of this relationship, which has become known as Hubble's Law.
Mathematically, Hubble's Law states that the velocity of recession (V) is directly proportional to the galactic distance (d). The equation is V = Hd, where H is the Hubble constant, or constant of proportionality.
The most current estimate of H is 70 kilometers per second per megaparsec. Hubble's Law is a major piece of evidence that the universe is expanding — his work formed the basis of the big bang theory of the origin of the universe.
The Doppler Effect
Much like the high-pitched sound from a fire-truck siren gets lower as the truck moves away, the movement of stars affects the wavelengths of light that we receive from them. This phenomenon is called the Doppler Effect.
We can measure the Doppler Effect by measuring lines in a star's spectrum and comparing them to the spectrum of a standard lamp. The amount of the Doppler shift tells us how fast the star is moving relative to us.
In addition, the direction of the Doppler shift can tell us the direction of the star's movement. If the spectrum of a star is shifted to the blue end, the star is moving toward us; if the spectrum is shifted to the red end, the star is moving away from us.
Active Galaxies
When you look at a normal galaxy, most of the light comes from the stars in visible wavelengths and is evenly distributed throughout the galaxy.
However, if you observe some galaxies, you'll see intense light coming from their nuclei. And if you look at these same galaxies in the X-ray, ultraviolet, infrared and radio wavelengths, they appear to be giving off enormous amounts of energy, apparently from the nucleus.
These are active galaxies, which represent a very small percentage of all galaxies. There are four classifications of active galaxy, but the type we observe may depend more upon our viewing angle than structural differences:
Seyfert galaxies
Radio galaxies
Quasars
Blazars
Black Holes
To explain active galaxies, scientists must be able to explain how they emit such large amounts of energy from such small areas of the galactic nuclei. The most accepted hypothesis is that at the center of each of these galaxies is a massive or supermassive black hole.
Around the black hole is an accretion disk of rapidly spinning gas that's surrounded by a torus (a donut-shaped disk of gas and dust). As the material from the accretion disk falls into the area around the black hole (the event horizon), it heats to millions of degrees Kelvin and is accelerated outward in the jets.
Seyfert Galaxies
Discovered by Carl Seyfert in 1943, these galaxies (2 percent of all spiral galaxies) have broad spectra indicating cores of hot, low-density ionized gas. The nuclei of these galaxies change brightness every few weeks, so we know that the objects in the center must be relatively small (about the size of a solar system).
Using Doppler shifts, astronomers have noticed that velocities at the center of Seyfert galaxies are about 30 times greater than those of normal galaxies.
Radio Galaxies
Radio galaxies are elliptical (0.01 percent of all galaxies are radio galaxies). Their nuclei emit jets of high-velocity gas (near the speed of light) above and below the galaxy — the jets interact with magnetic fields and emit radio signals.
Quasars
Quasars (quasi-stellar objects) were discovered in the early 1960s. About 13,000 have been discovered, but there could be as many as 100,000 out there [source: A Review of the Universe]. They're billions of light years away from the Milky Way and are the most energetic objects in the universe.
The extreme brightness of quasars can fluctuate over daylong periods, which indicates that the energy is coming from a very small area. Thousands of quasars have been found, and they're believed to be emanating from the cores of distant galaxies.
Blazars
Blazars are a type of active galaxy — about 1,000 have been cataloged [source: A Review of the Universe]. From our viewpoint, we are looking "head on" at the jet emanating from the galaxy. Like quasars, their brightness can fluctuate rapidly — sometimes in less than one day.
Starburst Galaxies
Most galaxies have low rates of new star formation — about one a year. However, starburst galaxies produce more than 100 a year. At this pace, starburst galaxies use up all of their gas and dust in about 100 million years, which is short compared to the billions of years that most galaxies have been around.
Starburst galaxies emit their intense light from a small area of newly formed stars and supernovae. So, astronomers think that starburst galaxies represent some short phase in how galaxies change and evolve, perhaps a stage prior to becoming an active galaxy.
'Rogue' star won't collide with our solar system in 29,000 years after all
Robert Lea
Tue, November 7, 2023
A white star zooms through space.
The solar system of the far future is safe from a run-in with a runaway dead star.
Last year, researchers looked at the trajectory of a rogue white dwarf star called WD 0810–353 with the Gaia space telescope and predicted that it was due for an encounter with our solar system in around 29,000 years. While this may seem a long time in human terms, it is a relatively short period cosmically speaking. For instance, the sun won't run out of hydrogen and swell out as a red giant for another 5 billion years, destroying Earth and the inner planets in the process.
While the sun's fate is likely sealed, new research has revealed that our planet at least won't have to worry about being decimated by the chaos caused by runaway white dwarf WD 0810–353 after all. In fact, the "rogue" star won't just miss the solar system; it might not even be headed our way at all, astronomers say.
"We found that the approach speed measured by the Gaia project is incorrect, and the close encounter predicted between WD0810–353 and the sun is actually not going to happen," astronomer Stefano Bagnulo said in a statement. "In fact, WD0810–353 may not even be moving towards the sun at all. That's one less cosmic hazard we have to worry about!"
Related: Fast-spinning white dwarf pulsar, the 2nd we've ever discovered, sheds light on how stars evolve
What did Gaia get wrong?
Gaia is a space telescope that is currently building an extraordinarily precise three-dimensional map of more than a billion stars throughout our Milky Way galaxy. It does this by precisely measuring the positions of stars and tracking changes in these positions by returning this "slice" of the sky and observing it again to see what has changed.
In 2022, astronomers Vadim Bobylev and Anisa Bajkova analyzed the vast Gaia dataset, searching for stars that appear to be heading toward the solar system. This led them to WD 0810–353, a white dwarf star — a type of dense stellar remnant left behind when stars with masses similar to the sun die.
Our own sun will become a white dwarf about a billion years after its destructive red giant spell when the swelled outer layers of the sun will cool and move away, leaving behind a smoldering core.
WD 0810–353 might offer a preview of what the sun will look like at that time when it comes to within around half a light-year of the solar system, about 31,000 times the distance between Earth and the sun.
While this seems like anything but a close encounter, it is close enough that the gravitational influence of WD 0810–353 could disturb the Oort cloud — a body of comets and other icy bodies at the edge of the solar system.
The Oort cloud is located between 2,000 and 100,000 times the distance between Earth and the sun from the solar system's central star. When the cloud gets shuffled by passing stars like WD 0810–353, the star's gravity could send some of these loosely gravitationally bound icy bodies plummeting toward the inner solar system and Earth.
So, what happened with the observations of this rogue white dwarf? What made astronomers think it was heading our way, and how do we know it probably isn't?
a map of the solar system showing distant bodies beyond Neptune
A magnetic mix-up
When making its observations of WD 0810–353, it turns out Gia missed something important and unusual about this white dwarf. It has a strangely large magnetic field.
"Unusually, this old white dwarf also has a huge magnetic field," explains Eva Villaver, an astronomer at the Astrobiology Center in Spain and co-author of the study. "In astronomy, magnetic fields are crucial to understanding many physical aspects of a star, and not considering them can lead to misinterpretations of physical phenomena."
The astronomers had determined WD 0810–353 was heading toward us by calculating the white dwarf's radial velocity — the velocity of an object along the line of sight from the observer to that object. This is done by looking at the spectrum of light being emitted by the star and then splitting that down into constituent wavelengths that make up that light.
If a star is moving away us, that scrunches up wavelengths, which has the effect of shifting the light down to the red end of the electromagnetic spectrum, a phenomenon known as redshift. If a star is moving toward us, however, the wavelength of light it emits is stretched and moves toward the blue end and is described as being "blueshifted."
The thing is that magnetic fields can also affect the spectrum of light from a star, dead or not, by splitting spectral lines and shifting lines to other wavelengths.
Crisis averted…
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To determine if this was the case with WD 0810–353, Bagnulo turned to the Very Large Telescope (VLT) located in northern Chile, and in particular, an instrument called the FOcal Reducer and low dispersion Spectrograph 2 (FORS2).
FORS2 let the team get a highly accurate picture of the spectra of WD 0810–353 and see if its intense magnetic field was messing with Gaia. This is possible because light waves usually oscillate in all directions, but when introduced to a magnetic field, they start to oscillate in a preferred direction — becoming "polarized."
Using polarized light from this white dwarf, the team modeled the magnetic field of the dead star and found its trajectory and velocity could actually be the result of a strong magnetic field. That means the solar system is likely safe from this particular rogue white dwarf.
The team's research is published in the Astrophysical Journal.
What Would Happen if a Solar Storm Hit Earth?
Laurie L. Dove, Desiree Bowie
Wed, November 8, 2023
Solar flares, which can impact Earth's environment, are magnetic explosions on the sun's surface.
What Is a Solar Storm?
A solar storm involves disturbances on the sun, such as solar flares and coronal mass ejections (CMEs), which release streams of energetic particles and massive bubbles of gas threaded with magnetic field lines into space.
These events can impact Earth and other planets when the particles interact with planetary magnetic fields and atmospheres.
These storms often follow sunspot cycles and can propel particles toward Earth at high speeds. When these particles collide with Earth's magnetic field, they can cause geomagnetic storms that result in beautiful auroras, also known as the northern and southern lights.
However, they can also pose risks to satellites, power grids and communication networks. The intensity of solar storms can vary, with some being minor and causing little effect, while others can be powerful enough to disrupt Earth's magnetosphere and ionosphere, leading to significant technological disturbances.
Ranking the Intensity of Solar Storms
The NOAA Space Weather Scales is a standardized system developed by the National Oceanic and Atmospheric Administration (NOAA) to rank and categorize the severity of space weather events, specifically geomagnetic storms.
Much like the scales used for tornadoes or hurricanes, NOAA's scale provides a clear framework for understanding the potential impact of these celestial disturbances on Earth and its technological infrastructure.
The scale ranges from 1 (minor) to 5 (extreme) and is based on the potential impact on power systems, satellite operations and other technological systems, as well as the visibility of auroras at specific geographical latitudes.
By using this scale, NOAA aims to provide clear warnings and timely information to stakeholders, ensuring preparedness and mitigation during significant solar events.
Now let's go back in time to the 19th century to explore the largest solar storm ever recorded and its impact on Earth.
The Carrington Event
It started like any other morning. Richard Carrington climbed the steps leading to an amateur observatory housed at his rural London estate, cranked open the shuttered dome and aimed a large brass telescope at a clear, blue sky.
He recorded the moment — 11:18 a.m., Sept. 1, 1859 — and then, as the sun came into view, began to sketch a group of large sunspots.
As he did, two points of light emerged, intensified and bloomed right before his eyes. Five minutes later, the blinding flares were gone. Although he didn't yet realize it, Carrington had witnessed what would become known as the largest solar flare in modern history.
The white-light solar flare, which someday would bear Carrington's name, was actually a magnetic explosion on the sun's surface.
It was so powerful that it briefly outshone the sun and, within a few hours, caused brilliant red, green and purple lights in the sky to erupt all over Earth (such light shows are colorful and common side effects of solar flares with coronal mass ejections).
It also supercharged telegraph cables that shocked operators, set telegraph paper afire and, in some cases, transmitted messages even when the lines were disconnected from their batteries.
What Will Happen if a Large-scale Solar Flare Hits Earth?
Although there's still evidence of solar material erupting frequently on the sun, none have reached the magnitude of the 1859 event. But what if one did?
We have some idea based on lesser solar flare explosions that produced clouds of charged particles that have crashed into Earth's magnetic field, causing the field to waver in what researchers call a "geomagnetic storm." [source: NOAA]
In February 2011, for example, a solar storm interrupted GPS signals for several minutes, which could potentially have spelled disaster for commercial airplanes or ships relying on GPS guidance systems to land or dock during that time. [source: NASA]
Over a decade afterward, on April 21, 2023, a powerful solar event sent a fast-moving burst of plasma toward Earth, causing a severe geomagnetic storm two days later.
This storm disrupted power, communication systems and satellite functions. It also created brilliant auroras. Monitored by NOAA's DSCOVR spacecraft, this was the third major storm of its kind in the current solar cycle, following similar events in 2021 and earlier in 2023.
Tech Interference
If a "Carrington-sized" solar flare were to hit Earth today, it would emit X-rays and ultraviolet light, which would reach Earth's atmosphere and interfere with electronics, as well as radio and satellite signals.
It would also cause a solar radiation storm, which could potentially be deadly to astronauts not fully equipped with protective gear and unprotected by Earth's atmosphere.
Finally, a cloud of charged particles (that coronal mass ejection we mentioned earlier) would bump against Earth's magnetic field. Such an event would mean outages that would decommission everything from cell phones and computers to automobiles and airplanes. Cities would lose power for weeks and, potentially, months — and many activities necessary to daily life would no longer be possible.
Take a trip to refuel at a gas station, for example. Simply using a credit or debit card to pay for a few gallons of gas requires a satellite transaction, and creating one would no longer be possible.
The potential consequences of a large-scale solar flare hitting Earth have scientists scrambling to develop an early warning system and new solar flare detection methods, much like their predecessors once learned to forecast deadly tornadoes and other weather events. Someday, we might just have solar flare warnings alongside hurricane warnings and thunderstorm watches.
How to Prepare for Extreme Solar Storms
As the old saying goes, if you stay ready, you don't have to get ready. If you're concerned about how to safely make it through a massive solar storm, here are some steps you can take for peace of mind:
Stay informed: Follow space weather forecasts from official sources like the NOAA Space Weather Prediction Center to stay updated on solar activity.
Emergency kit: Have an emergency preparedness kit ready with essentials like water, nonperishable food, a flashlight, batteries, a first-aid kit and cash, in case of prolonged power outages from downed electricity grids.
Protect electronics: Use surge protectors for electronic devices and consider unplugging sensitive electronics during severe solar storms to prevent damage from power surges.
Data backups: Regularly back up important data from computers and mobile devices to cloud services or external hard drives.
Communication plan: Have a plan for alternative communication, such as text messaging or using a satellite phone, as cell towers and landlines could be affected.
Alternate power: Consider investing in alternative power sources such as solar-powered chargers or generators for essential power needs.
Vehicle safety: If you rely on GPS navigation, keep paper maps in your vehicle and familiarize yourself with alternative routes.
Home preparations: If you have a home solar panel system, check with the installer about protective measures against geomagnetically induced currents.
This article was updated in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.
Lots More Information
Sources
Bell, Trudy, and Tony Phillips. "A Super Solar Flare." NASA. May 6, 2008. (April 10, 2015) http://science.nasa.gov/science-news/science-at-nasa/2008/06may_carringtonflare/
Lovett, Richard. "What if the Biggest Solar Storm on Record Happened Today?" National Geographic. March 4, 2011. (April 10, 2015) http://news.nationalgeographic.com/news/2011/03/110302-solar-flares-sun-storms-earth-danger-carrington-event-science/
A Nearby Kilonova Explosion Could End All Life on Earth. It's Probably Fine.
Darren Orf
Tue, November 7, 2023
How a Kilonova Explosion Could End Life on EarthUniversity of Warwick/Mark Garlick, CC BY 4.0 , via Wikimedia Commons
Analyzing data from GW170817, the first kilonova ever discovered, scientists at the University of Illinois Urbana-Champaign discerned what would happen if an explosion like that ever occurred in our cosmic backyard.
According to the study, the greatest threat would take the form of a bubble of cosmic rays that would ionize the Earth’s ozone and make the planet uninhabitable for thousands of years.
Luckily, this is an unlikely scenario, as the binary neutron mergers that produce kilonovas are extremely rare. One has yet to be found in our galaxy.
Space is an inhospitable place—for people and planets. Stars go supernova, black holes swallow basically everything, and rogue planets careen through the galaxy, ready to dramatically disrupt stellar systems. Now, scientists are adding another doomsday scenario to this world-ending nightmare list—kilonovas.
According to scientists at the University of Illinois Urbana-Champaign, a kilonova—an explosion caused by two colliding neutron stars—located within 35 light years of Earth could bathe the planet in cosmic rays and exterminate life for thousands of years. Scientists analyzed data from GW170817, the first kilonova ever discovered, and uploaded the results of that work last week to the preprint server arXiv.
“As the awareness and understanding of powerful cosmic transients have grown, so also has the realization of their dangers,” the paper reads. “We found that cosmic rays are the most threatening emissions and are potentially lethal…even if it never induced a mass extinction, a nearby kilonova event would be visible on Earth. It would likely disrupt technology soon after the merger and remain bright in the sky for over a month.”
Cosmic rays are energetically charged particles that bombard the Earth at all times—both from our own Sun and from distant sources throughout the universe. The cosmic ray bubble that would issue from the center of a kilonova explosion could impact planets 36 light years away. And because cosmic rays hang around longer than other types of rays rays, they’d leave planets lifeless for thousands of years.
But cosmic rays are only one threat posed by these giant space explosions. While it's less likely to hit us, the most intense threat is the two jets of gamma radiation that emitted from the kilonova. If caught in a jet’s path, the gamma rays would ionize our ozone and leave our planet susceptible to UV radiation, dooming Earth from as far as 297 light years away.
And if Earth is not in the path of this cue ball of doom, the kilonova has other options. It also issues a “cocoon” of gamma radiation in all directions that would affect planets up to 13 light years away. Damage from this cocoon could take the ozone four years to recover from—more than enough time for UV radiation to wreak havoc on the planet. Neutron star mergers also create an “X-ray afterglow” when gamma radiation hits the interstellar medium, but planets would need to be within 16 light years to be affected by that particular effect.
Thankfully, this specific cosmic doomsday scenario is highly improbable. For one, binary neutron mergers are extremely rare. Scientists estimate that for 100 billion stars, only 10 of them are destined to become binary neutron star mergers. And of the handful of kilonovae we’ve discovered, none of them are in our galaxy.
But while we might be out of the “death by kilonova” woods, dangers lurk around every cosmic corner. Even our own life-giving Sun could put us in danger. The universe is a perilous place, and we’re just trying to live in it.
Bill Shannon
Tue, November 7, 2023
(WTAJ) — One of the most awe-inspiring sights in our solar system, Saturn, is about to lose its iconic look.
Well, sort of.
As Saturn dances in the night sky, it tilts on an axis, much like Earth. The planet takes 29.4 Earth years to complete an orbit around the sun. It rotates quickly, though, making a day on Saturn only 10.7 Earth hours, according to NASA.
This June 2023 image provided by the Space Telescope Science Institute shows the planet Saturn and three of its moons, from left, Enceladus, Tethys and Dione, captured by the James Webb Space Telescope. In infrared, the planet appears dark because sunlight is absorbed by methane in the atmosphere. (NASA, ESA, CSA, JWST Saturn Team via AP)More
While it’s known to scientists that Saturn’s rings are slowly (as in over the next millions of years) being pulled into the planet’s atmosphere, 2025 will be a bit different.
What’s happening to Saturn’s rings?
Saturn is transitioning and as its tilt changes, it will align the edge of its rings directly with Earth. Think of it as trying to see a piece of paper edge-on from the opposite endzone of a football field.
Fear not, though. Saturn will continue its celestial dance and by the year 2032, it’s predicted the transition will give us a marvelous look at the underside of its rings, according to Space.com.
Northern lights could ramp up next year, and so could these strange occurrences
This event happens roughly every 15 years, according to NASA. We’ll cross Saturn’s ring plane on March 23, 2025, specifically, but there can be anywhere from one to three crossings per half-orbit of Saturn.
While Saturn’s rings will seemingly “disappear” in two years, we won’t have an entirely “ringless” view until the “triple passage” in 2038 and 2039. According to NASA, on October 15, 2038, and April 1 and July 9, 2039, we’ll experience “favorable ring plane crossings” that will make Saturn appear even more ringless.
NASA predicts large asteroid impact could be in Earth’s future
While we won’t be able to see Saturn’s rings in 2025, this cosmic event should offer a great view of many of Saturn’s 146 moons.
Speaking of moons, scientists with NASA believe the mass of moons orbiting the planet is what causes the tilt of Saturn to alter and it will continue to happen over the next billion years.
Saturn's rings will disappear from view for a time. This is why and when
Manahil Ahmad, NorthJersey.com
Wed, November 8, 2023
If you love looking at the stunning rings of Saturn, here's a heads-up: They're going to vanish from our view briefly.
According to reports from the International Federation of Learning in Science, this rare occurrence is expected to take place in 2025. As Saturn embarks on its 30-year journey around the sun, a unique alignment will briefly obscure our unobstructed view of these enigmatic rings.
Saturn's rings are beautiful bands of ice and rock that surround the planet. They're made up of tiny pieces and huge boulders that move around the planet, creating this famous ring system. Scientists think these rings might be leftovers from a moon that got too close to Saturn and broke apart due to the planet's strong gravity.
The thing is, Saturn's rings don't always look the same. Because of the way Saturn moves, the angle at which we see the rings changes. This intriguing phenomenon occurs roughly every 15 years due to the unique orbital dynamics of the Saturnian system. As the planet transitions through its orbit, the rings align with our line of sight in such a way that they seem to disappear.
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It is essential to note that while Saturn's rings may briefly vanish from sight, this is a natural occurrence, and they will reappear as Saturn's position in its orbit changes. This disappearance provides scientists with an opportunity to learn more about the composition and structure of the rings when they are seen edge-on, offering a fresh perspective on these cosmic wonders.
So, get ready to say goodbye temporarily to Saturn's rings in 2025, and be prepared to welcome them back with open arms. It's a reminder that the universe is full of surprises and keeps us in awe of its beauty.
This article originally appeared on NorthJersey.com: Saturn rings to disappear from view briefly in 2025
Evidence of alien life may exist in the fractures of icy moons around Jupiter and Saturn
Robert Lea
Wed, November 8, 2023
Dual image showing saturn with a transiting moon on the left, and a grey planetary body on the right.
Scientists are investigating specific geological features on the largest moons of both Jupiter and Saturn that could be ideal spots for the emergence of life elsewhere in the solar system.
The team, led by researchers from the University of Hawaii at Mānoa, looked at what are called "strike-slip faults" on the Jovian moon, Ganymede — the solar system’s largest moon, bigger even than the planet Mercury — and Saturn's moon, Titan. Faults like these happen when fault walls move past each other horizontally, either to the left or the right, with a famous example here on Earth being the San Andreas fault. It's sort of like a giant crack, rift, or certain type of crevice in the ground.
Such seismic features are generated on these icy moons, scientists believe, when these bodies orbit their parent gas-giant planets. The planets' immense gravitational influences generate tidal forces that squash and squeeze the moons, inevitably flexing the natural satellites' surfaces. Plus, these tidal forces aren’t very consistent because the orbits of both moons are elliptical, meaning they are sometimes closer to Saturn or Jupiter. Other times, they're much farther away. That, in turn, leads to even stronger tidal forces.
"We are interested in studying shear deformation on icy moons because that type of faulting can facilitate the exchange of surface and subsurface materials through shear heating processes, potentially creating environments conducive for the emergence of life," Liliane Burkhard, lead author of the research and a scientists at the Hawaii Institute of Geophysics and Planetology, said in a statement.
Related: NASA’s Juno probe detects organic compounds on huge Jupiter moon Ganymede
Strike-slip faults on Titan
Saturn’s moon, Titan, has surface temperatures of around minus 290 degrees Fahrenheit (minus 179 degrees Celsius). This is incredibly cold — cold enough that the water of this moon actually plays the role of rock. It can crack, deform and, ultimately, form faults.
During its flybys of Titan, NASA’s Cassini spacecraft was able to determine that this moon of Saturn may have liquid water oceans tens of miles beneath its thick shell of ice. Additionally, Titan is the only solar system moon with a dense, Earth-like atmosphere, meaning it has a similar hydrological cycle with methane clouds, rain and liquid flowing across the surface to fill lakes and seas. For this reason, Titan is already considered one of just a few bodies in our solar system that could support life — as we know it, at least.
When the NASA Dragonfly mission (which launches in 2027) arrives at Titan in 2034, it will send a rotorcraft lander to fly across the frigid surface of this moon in an effort to hunt for those potential biological signs. That doesn't exactly mean it'll search for bug-eyed aliens, however. At the very least, the team hopes the lander will detect the chemical building blocks of life we're familiar with.
The Dragonfly mission is initially set to land at the Selk crater area on Titan, a region that is also of interest to Burkhard and the team. This is because when calculating the stress exerted on Titan’s surface as a result of tidal forces, the researchers weren't only focused on whether there might be signs of extraterrestrial life on the ground. They also explored the chance that the Selk crater region could be subjected to shear deformation to figure out whether it's a safe landing site option for Dragonfly in the first place.
"While our prior research indicated that certain areas on Titan might currently undergo deformation due to tidal stresses, the Selk crater area would need to host very high pore fluid pressures and a low crustal coefficient of friction for shear failure, which seems improbable," said Burkhard. "Consequently, it’s safe to infer that Dragonfly won’t be landing in a strike-slip ditch!"
Three images show strike-slip faults at the San Andreas Fault (a) on Ganymede (b) and on Titan
Burkhard and colleagues also looked at the geology of the Jovian moon, Ganymede, to investigate the icy body’s history of tidal stress. In particular, the team looked at a bright region in the northwest of Ganymede called Philus Sulcus, which is composed of parallel sets of fractures.
The researchers basically looked at available high-resolution observations of the area to find that there were different degrees of tectonic deformation in bands of light terrain that cross over each other. The cross-cutting nature of these bands indicated to Burkhard and colleagues the existence of three distinct eras of geological activity — ancient, intermediate, and young.
"I investigated strike-slip faulting features in intermediate-aged terrain, and they correspond in slip direction to the predictions from modeling stresses of a higher past eccentricity," said Burkhard. "Ganymede could have undergone a period where its orbit was much more elliptical than it is today."
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When investigating other parts of Philus Sulcus, the team found the direction of slip features to have different alignments. This implies these features may have been generated by processes other than high tidal stress. "So, Ganymede has had a tidal 'midlife crisis,' but its youngest 'crisis' remains enigmatic," Burkhard added.
The geologic investigations undertaken by this team and others are vital for informing the missions of spacecraft that aim to explore solar system moons like Titan and Ganymede. said Burkhard.
“Missions such as Dragonfly, Europa Clipper, and ESA’s JUICE will further constrain our modeling approach and can help pinpoint the most interesting locations for lander exploration and possibly for gaining access to the interior ocean of icy moons,” Burkhard concluded.
The team’s research is published across two papers in the journal Icarus.
The Juno spacecraft spotted evidence of a salty ocean on Jupiter's biggest moon
Briley Lewis
Wed, November 8, 2023
Juno observed Jupiter and three of its moons, including Ganymede, furthest to the left.
NASA’s Juno spacecraft has been exploring Jupiter since it arrived at the planet in 2016. In recent years, the mission has turned its attention to the gas giant’s many moons, including the hellish volcanic world Io and the ice ball Europa. Now, in research published in Nature Astronomy, the Juno team revealed new photos of Jupiter’s largest moon, Ganymede, which show evidence of salts and organic compounds. These materials are likely the residue of salty sea water from an underground ocean that bubbled up to the frozen surface of Ganymede. And, excitingly, a salty ocean indicates conditions there might be conducive to life.
Ganymede is a particularly weird place. Not only is it Jupiter’s most massive satellite, it’s the biggest moon in the whole solar system—it’s even larger than the planet Mercury. It also is the only moon to have its own magnetic field, generated from a molten metal core deep in its interior. Like other icy worlds of the outer solar system, such as Europa or possibly Pluto, Ganymede probably has an ocean lurking under its icy crust. Some studies suggest multiple seas, stacked together in a layer cake of ice sheets and oceans, hide underground.
“Because Ganymede is so big, its interior structure is more complicated” than that of smaller worlds, explains University of Arizona geologist Adeene Denton, who is not affiliated with the new work. She notes that the moon’s massive size means there’s a lot of space for interesting molecules to mix about. But that also means they’re tricky to spot, because material must cover a large distance to get to the surface where our spacecraft can see them.
Juno finally passed close enough to Ganymede—within 650 miles, less than the distance from New York City to Chicago—to take a close look at the chemicals on its surface using its Jovian InfraRed Auroral Mapper (JIRAM). This incredible instrument tracked the composition of Ganymede’s surface in great detail, noting features as small as 1 kilometer wide. If JIRAM were looking at New York City, it would be able to map Manhattan in ten-block chunks.
Importantly, material on the surface of Ganymede might tell us about the water hiding below. If there are salts above, the subsurface ocean might have that same brine. Oceans, including the ones on Earth, acquire their salt from chemical interactions where liquid water touches a rocky mantle. This kind of exchange is “one of the conditions necessary for habitability,” says lead author Federico Tosi, research scientist at the National Institute for Astrophysics in Rome, Italy.
However, other current research suggests that Ganymede doesn’t have a liquid water layer directly touching its mantle. Instead, icy crusts separate the ocean from the rock. But because the team did see these salts in the JIRAM data, it suggests they were touching at one point in the past, if not now. “This testifies to an era when the ocean must have been in direct contact with the rocky mantle,” explains Tosi.
As for the organic chemicals that Juno detected, the team still isn’t completely sure what flavor of compound they are. They’re leaning towards aliphatic aldehydes, a type of molecule found elsewhere in the solar system that’s known as an intermediate step necessary to build more complex amino acids. These usually indicate liquid water and a rocky mantle are interacting. This definitely isn’t a detection of life, but it’s interesting for the possibility of life lurking in Ganymede’s hidden oceans. “The presence of organic compounds does not imply the presence of life forms,” says Tosi. “But the opposite is true: life requires the presence of some categories of organic compounds.”
Unfortunately, Juno won’t have a chance to swing by Ganymede again to search for more salty shores—instead, it’s headed toward the explosive Io. The probe’s most recent survey of these minerals was a “a unique opportunity to take a close look at this satellite,” Tosi says. We won’t have to wait too much longer, though, for a second visit. In about ten years, he adds, we’ll get another chance to explore these salty waters with the ESA JUICE mission, “which is expected to achieve complete and unprecedented coverage of Ganymede.”
Just How Many Galaxies Are in the Universe?
Craig Freudenrich, Ph.D.
Wed, November 8, 2023
The Andromeda galaxy, pictured here, is just one of many in the known universe.
Tony Rowell / Getty Images
When you look up at the night sky, especially during the summer, you'll see a faint band of stars spread across the entire middle of the sky. The sun is just one of about 200 billion stars in the Milky Way, our home galaxy, which is just one galaxy in the universe. So, how many galaxies are in the universe?
In this article, we'll find out how galaxies were discovered and what types exist, what they're made of, their internal structures, how they form and evolve, how they're distributed across the universe, and how active galaxies might emit so much energy.
What Is a Galaxy?
A galaxy is a large system of stars, gas (mostly hydrogen), dust and dark matter that orbits a common center and is bound together by gravity — you can think of them as "island universes."
There are many types of galaxies spanning all sorts of shapes and sizes. We know that they're very old and formed early in the evolution of the universe. Yet how they formed and evolved into their various shapes remains a mystery.
When astronomers look into the deepest reaches of the universe with powerful telescopes, they see myriads of galaxies. The galaxies are far away from one another and constantly moving away from one another as our universe expands.
Furthermore, galaxies are organized into large clusters and other structures, which could have important implications for the overall structure, formation and fate of the universe.
Active Galaxies
Some galaxies, called active galaxies, emit huge amounts of energy in the form of radiation. They may have exotic structures such as supermassive black holes at their centers. Active galaxies represent an important area of astronomical research.
Luminosity-distance Relationship
Astronomers (professional or amateur) can measure a star's brightness (the amount of light it puts out) by using a photometer or charge-coupled device on the end of a telescope. If they know the star's brightness and the distance to the star, they can calculate its luminosity — the amount of energy that it puts out (luminosity = brightness x 12.57 x (distance)2).
Conversely, if you know a star’s luminosity, you can calculate its distance.
How Many Galaxies Are in the Universe?
There could be as many as two trillion galaxies in the universe.
In the early 2000s, scientists estimated that there were 200 billion galaxies in the universe. However, in 2016, a survey of Hubble Space telescope data conducted at the University of Nottingham found that the total number of galaxies in the observable universe was at least 10 times that [source: NASA].
When you look up at the night sky, especially during the summer, you'll see a faint band of stars spread across the entire middle of the sky. The sun is just one of about 200 billion stars in the Milky Way, our home galaxy, which is just one galaxy in the universe. So, how many galaxies are in the universe?
In this article, we'll find out how galaxies were discovered and what types exist, what they're made of, their internal structures, how they form and evolve, how they're distributed across the universe, and how active galaxies might emit so much energy.
What Is a Galaxy?
A galaxy is a large system of stars, gas (mostly hydrogen), dust and dark matter that orbits a common center and is bound together by gravity — you can think of them as "island universes."
There are many types of galaxies spanning all sorts of shapes and sizes. We know that they're very old and formed early in the evolution of the universe. Yet how they formed and evolved into their various shapes remains a mystery.
When astronomers look into the deepest reaches of the universe with powerful telescopes, they see myriads of galaxies. The galaxies are far away from one another and constantly moving away from one another as our universe expands.
Furthermore, galaxies are organized into large clusters and other structures, which could have important implications for the overall structure, formation and fate of the universe.
Active Galaxies
Some galaxies, called active galaxies, emit huge amounts of energy in the form of radiation. They may have exotic structures such as supermassive black holes at their centers. Active galaxies represent an important area of astronomical research.
Luminosity-distance Relationship
Astronomers (professional or amateur) can measure a star's brightness (the amount of light it puts out) by using a photometer or charge-coupled device on the end of a telescope. If they know the star's brightness and the distance to the star, they can calculate its luminosity — the amount of energy that it puts out (luminosity = brightness x 12.57 x (distance)2).
Conversely, if you know a star’s luminosity, you can calculate its distance.
How Many Galaxies Are in the Universe?
There could be as many as two trillion galaxies in the universe.
In the early 2000s, scientists estimated that there were 200 billion galaxies in the universe. However, in 2016, a survey of Hubble Space telescope data conducted at the University of Nottingham found that the total number of galaxies in the observable universe was at least 10 times that [source: NASA].
2008 HowStuffWorks
Galaxy Types
Galaxies come in a variety of sizes and shapes. They can have as few as 10 million stars or as many as 10 trillion (the Milky Way has about 200 billion stars). In 1936, Edwin Hubble classified galaxy shapes in the Hubble Sequence.
Elliptical Galaxy
These have a faint, rounded shape, but they're devoid of gas and dust, with no visible bright stars or spiral patterns. They also don't have galactic disks, which we'll learn about below.
Their classification varies from E0 (circular) to E7 (most elliptical). Elliptical galaxies probably comprise about 60 percent of the galaxies in the universe.
They show wide variation in size — most are small (about 1 percent the diameter of the Milky Way), but some are about five times larger than the diameter of the Milky Way.
Spiral Galaxy
The Milky Way is one of the larger spiral galaxies. They're bright and distinctly disk-shaped, with hot gas, dust and bright stars in the spiral arms. Because spiral galaxies are bright, they make up most of the visible galaxies, but they're thought to make up only about 20 percent of the galaxies in the universe.
Spiral galaxies are subdivided into these categories:
S0: Little gas and dust, with no bright spiral arms and few bright stars
Normal spiral: Obvious disk shape with bright centers and well-defined spiral arms. Sa galaxies have large nuclear bulges and tightly wound spiral arms, while Sc galaxies have small bulges and loosely wound arms.
Barred spiral: Obvious disk shape with elongated, bright centers and well-defined spiral arms. SBa galaxies have large nuclear bulges and tightly wound spiral arms, while SBc galaxies have small bulges and loosely wound arms (the Milky Way may be a SBc galaxy).
Irregular Galaxy
These are small, faint galaxies with large clouds of gas and dust, but no spiral arms or bright centers. Irregular galaxies contain a mixture of old and new stars and tend to be small, about 1 percent to 25 percent of the Milky Way's diameter.
Galaxy Parts
Spiral galaxies have the most complex structures. Here's a view of the Milky Way as it would appear from the outside.
2008 HowStuffWorks
Galactic Disk
Most of the Milky Way's more than 200 billion stars are located here. The disk itself is broken up into these parts:
Nucleus: The center of the disk
Bulge: The area around the nucleus, including the immediate areas above and below the plane of the disk
Spiral arms: These extend outward from the center; our solar system is located in one of the spiral arms of the Milky Way.
Globular Clusters
A few hundred of these are scattered above and below the disk. The stars here are much older than those in the galactic disk.
Halo
A halo is a large, dim, region that surrounds the entire galaxy. It's made of hot gas and possibly dark matter.
Gravity
All of these components orbit the nucleus and are held together by gravity. Because gravity depends upon mass, you might think that most of a galaxy's mass would lie in the galactic disk or near the center of the disk.
However, by studying the rotation curves of the Milky Way and other galaxies, astronomers have concluded that most of the mass lies in the outer portions of the galaxy (like the halo), where there is little light given off from stars or gases.
History of Galaxies
Let's look at the history of galaxies in astronomy.
Early Observations
The Greeks coined the term "galaxies kuklos" for "milky circle" when describing the Milky Way. The Milky Way was a faint band of light, but they had no idea what it was composed of.
When Galileo looked at the Milky Way with the first telescope, he determined that it was made up of numerous stars.
We've known for centuries that our solar system was located within the Milky Way because the Milky Way surrounds us. We can see it throughout the year in all parts of the sky, but it's brighter during the summer, when we're looking at the center of the galaxy. However, to astronomers in the 18th century and earlier, it wasn't clear that the Milky Way was a galaxy and not just a distribution of stars.
18th-century Findings
In the late 18th century, astronomers William and Caroline Herschel mapped the distances to stars in many directions. They determined that the Milky Way was a disk-like cloud of stars with the sun near the center.
In 1781, Charles Messier cataloged various nebulae (faint patches of light) throughout the sky and classified several of them as spiral nebulae.
20th-century Discoveries
In the early 20th century, astronomer Harlow Shapely measured the distributions and locations of globular star clusters. He determined that the center of the Milky Way was 28,000 light-years from Earth, near the constellations of Sagittarius and Scorpio, and that the center was a bulge, rather than a flat area.
Shapely later argued that the spiral nebulae discovered by Messier were "island universes" or galaxies (retaining the Greek wording). However, another astronomer named Heber Curtis argued that spiral nebulae were merely part of the Milky Way.
The debate raged on for years because astronomers needed larger, more powerful, telescopes to resolve the details.
21st-century Innovations
In 1924, Edwin Hubble settled the debate. He used a large telescope with a 100-inch diameter — larger than ones that were available to Shapely and Curtis — at Mount Wilson in California and resolved that the spiral nebulae had structure and stars called Cepheid variables, like those in the Milky Way. (These stars change their brightness regularly, and the luminosity is directly related to the period of their brightness cycle.)
Hubble used the light curves of the Cepheid variables to measure their distances from Earth and found that they were much farther away than the known limits of the Milky Way. Therefore, these spiral nebulae were indeed other galaxies outside our own.
There are still many mysteries surrounding galaxy formation, but on the next page we'll explain some of the best theories about it.
Light-years Away
Galaxies are far apart. The Andromeda galaxy, which is also called M31 (Messier object #31), is the closest galaxy to us — 2.2 million light years away. Astronomers usually measure intergalactic distances in terms of megaparsecs:
one parsec = 3.26 light years
one million parsecs = one megaparsec
one megaparsec (Mpc) = 3.26 million light years
The farthest visible galaxies are approximately 3,000 Mpc away, or about 10 billion light years.
2008 HowStuffWorks
Galaxy Formation
We really don't know how various galaxies formed and took the many shapes that we see today. But we do have some ideas about their origins and evolution.
Shortly after the big bang about 14 billion years ago, collapsing gas and dust clouds might have lead to the formation of galaxies.
Interactions between galaxies, specifically collisions between galaxies, play an important role in their evolution.
Let's look at the period of galaxy formation.
Edwin Hubble's observations, and subsequent Hubble Law (which we'll in a moment), led to the idea that the universe is expanding. We can estimate the age of the universe based on the rate of expansion.
Because some galaxies are billions of light years away from us, we can discern that they formed fairly soon after the big bang (as you look deeper into space, you see further back in time).
Most galaxies formed early, but data from NASA's Galaxy Explorer (GALEX) telescope indicate that some new galaxies have formed relatively recently — "recently" meaning within the past few billion years, whereas early galaxies formed over 10 billion years ago.
Most theories about the early universe make two assumptions:
It was filled with hydrogen and helium.
Some areas were slightly denser than others.
Protogalactic Clouds
From these assumptions, astronomers believe that the denser areas slowed the expansion slightly, allowing gas to accumulate in small protogalactic clouds. In these clouds, gravity caused the gas and dust to collapse and form stars.
These stars burned out quickly and became globular clusters, but gravity continued to collapse the clouds. As the clouds collapsed, they formed rotating disks.
The rotating disks attracted more gas and dust with gravity and formed galactic disks. Inside the galactic disk, new stars formed. What remained on the outskirts of the original cloud were globular clusters and the halo composed of gas, dust and dark matter.
Two factors from this process might account for the differences between elliptical and spiral galaxies:
Angular momentum (degree of spin): Protogalactic clouds with more angular momentum could spin faster and from spiral disks. Slow-spinning clouds could have formed elliptical galaxies.
Cooling: High-density protogalactic clouds cooled faster, using up all the gas and dust in forming stars and leaving none for making a galactic disk (this is why elliptical galaxies don't have disks). Low-density protogalactic clouds cool more slowly, leaving gas and dust for disk formation (like in spiral galaxies).
2008 HowStuffWorks
When Galaxies Collide
Galaxies do not act alone. The distances between galaxies do seem large, but the diameters of galaxies are also large.
Compared to stars, galaxies are relatively close to one another. They can interact and, more importantly, collide. When galaxies collide, they actually pass through one another — the stars inside don't run into one another because of the enormous interstellar distances.
But collisions do tend to distort a galaxy's shape. Computer models show that collisions between spiral galaxies tend to make elliptical ones (so, spiral galaxies probably haven't been involved in any collisions). Scientists estimate that as many as half of all galaxies have been involved in some sort of collision.
Gravitational interactions between colliding galaxies could cause several things:
New waves of star formation
Supernovae
Stellar collapses that form the black holes or supermassive black holes in active galaxies
So, do galaxies just float around in space or does some unseen force regulate their movement? And what happens when they run into each other?
2008 HowStuffWorks
Galaxy Distribution
Galaxies aren't randomly distributed throughout the universe; they tend to exist in galactic clusters. The galaxies in these clusters are bound together gravitationally and influence one another.
Rich clusters contain 1,000 or more galaxies. The Virgo supercluster, for example, includes more than 2,500 galaxies and is located about 55 million light-years from Earth.
Poor clusters contain less than 1,000 galaxies. The Milky Way and the Andromeda galaxy (M31) are the major members of the Local Group, which contains 50 galaxies.
When astronomers Margaret Geller and Emilio E. Falco plotted the positions of galaxies and galactic clusters in the universe, it became clear that galactic clusters and superclusters are not randomly distributed.
They're actually clumped together in walls (long filaments) interspersed with voids, which gives the universe a cobweb-like structure.
The Intergalactic Medium
The intergalactic medium — the space between galaxies and clusters of galaxies — is not entirely empty. We don't know the exact nature of the intergalactic medium, but it probably contains a relatively small density of gas.
Most of the intergalactic medium is cold (about 2 degrees Kelvin), but X-ray observations suggest that some areas of it are hot (millions of degrees Kelvin) and rich in metals.
One of the active areas of astronomical research today is directed at determining the nature of the intergalactic medium — it may help us figure out exactly how the universe began and how galaxies form and evolve.
Hubble's Law
Let's look at one final property concerning galaxies and their distributions. For his measurements of galactic distances, Edwin Hubble studied the spectra of light that galaxies emit.
In all cases, he noted that the spectra were Doppler-shifted to the red end of the spectrum. This indicates that the object is moving away from us.
Hubble noticed that, no matter where he looked, galaxies were moving away from us. And the farther the galaxy, the faster it was moving away. In 1929, Hubble published a graph of this relationship, which has become known as Hubble's Law.
Mathematically, Hubble's Law states that the velocity of recession (V) is directly proportional to the galactic distance (d). The equation is V = Hd, where H is the Hubble constant, or constant of proportionality.
The most current estimate of H is 70 kilometers per second per megaparsec. Hubble's Law is a major piece of evidence that the universe is expanding — his work formed the basis of the big bang theory of the origin of the universe.
The Doppler Effect
Much like the high-pitched sound from a fire-truck siren gets lower as the truck moves away, the movement of stars affects the wavelengths of light that we receive from them. This phenomenon is called the Doppler Effect.
We can measure the Doppler Effect by measuring lines in a star's spectrum and comparing them to the spectrum of a standard lamp. The amount of the Doppler shift tells us how fast the star is moving relative to us.
In addition, the direction of the Doppler shift can tell us the direction of the star's movement. If the spectrum of a star is shifted to the blue end, the star is moving toward us; if the spectrum is shifted to the red end, the star is moving away from us.
Active Galaxies
When you look at a normal galaxy, most of the light comes from the stars in visible wavelengths and is evenly distributed throughout the galaxy.
However, if you observe some galaxies, you'll see intense light coming from their nuclei. And if you look at these same galaxies in the X-ray, ultraviolet, infrared and radio wavelengths, they appear to be giving off enormous amounts of energy, apparently from the nucleus.
These are active galaxies, which represent a very small percentage of all galaxies. There are four classifications of active galaxy, but the type we observe may depend more upon our viewing angle than structural differences:
Seyfert galaxies
Radio galaxies
Quasars
Blazars
Black Holes
To explain active galaxies, scientists must be able to explain how they emit such large amounts of energy from such small areas of the galactic nuclei. The most accepted hypothesis is that at the center of each of these galaxies is a massive or supermassive black hole.
Around the black hole is an accretion disk of rapidly spinning gas that's surrounded by a torus (a donut-shaped disk of gas and dust). As the material from the accretion disk falls into the area around the black hole (the event horizon), it heats to millions of degrees Kelvin and is accelerated outward in the jets.
Seyfert Galaxies
Discovered by Carl Seyfert in 1943, these galaxies (2 percent of all spiral galaxies) have broad spectra indicating cores of hot, low-density ionized gas. The nuclei of these galaxies change brightness every few weeks, so we know that the objects in the center must be relatively small (about the size of a solar system).
Using Doppler shifts, astronomers have noticed that velocities at the center of Seyfert galaxies are about 30 times greater than those of normal galaxies.
Radio Galaxies
Radio galaxies are elliptical (0.01 percent of all galaxies are radio galaxies). Their nuclei emit jets of high-velocity gas (near the speed of light) above and below the galaxy — the jets interact with magnetic fields and emit radio signals.
Quasars
Quasars (quasi-stellar objects) were discovered in the early 1960s. About 13,000 have been discovered, but there could be as many as 100,000 out there [source: A Review of the Universe]. They're billions of light years away from the Milky Way and are the most energetic objects in the universe.
The extreme brightness of quasars can fluctuate over daylong periods, which indicates that the energy is coming from a very small area. Thousands of quasars have been found, and they're believed to be emanating from the cores of distant galaxies.
Blazars
Blazars are a type of active galaxy — about 1,000 have been cataloged [source: A Review of the Universe]. From our viewpoint, we are looking "head on" at the jet emanating from the galaxy. Like quasars, their brightness can fluctuate rapidly — sometimes in less than one day.
Starburst Galaxies
Most galaxies have low rates of new star formation — about one a year. However, starburst galaxies produce more than 100 a year. At this pace, starburst galaxies use up all of their gas and dust in about 100 million years, which is short compared to the billions of years that most galaxies have been around.
Starburst galaxies emit their intense light from a small area of newly formed stars and supernovae. So, astronomers think that starburst galaxies represent some short phase in how galaxies change and evolve, perhaps a stage prior to becoming an active galaxy.
Lots More Information
Sources
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A Review of the Universe - Structures, Evolutions, Observations, and Theories. http://universe-review.ca/F05-galaxy.htm
A Teacher's Guide to the Universe. http://www.astro.princeton.edu/~clark/teachersguide.html.
Bennett, J et al. "The Cosmic Perspective (third edition)." Pearson, 2004.
Chandra X-ray Observatory - X-ray Astronomy Field Guide, Starburst Galaxies. http://chandra.harvard.edu/xray_sources/starburst.html
Galaxy Classification and Evolution Lab. http://cosmos.phy.tufts.edu/~zirbel/laboratories/Galaxies.pdf
Henry, J. Patrick et al. "The Evolution of Galaxy Clusters." Scientific American, December 1998.
Sources
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A Review of the Universe - Structures, Evolutions, Observations, and Theories. http://universe-review.ca/F05-galaxy.htm
A Teacher's Guide to the Universe. http://www.astro.princeton.edu/~clark/teachersguide.html.
Bennett, J et al. "The Cosmic Perspective (third edition)." Pearson, 2004.
Chandra X-ray Observatory - X-ray Astronomy Field Guide, Starburst Galaxies. http://chandra.harvard.edu/xray_sources/starburst.html
Galaxy Classification and Evolution Lab. http://cosmos.phy.tufts.edu/~zirbel/laboratories/Galaxies.pdf
Henry, J. Patrick et al. "The Evolution of Galaxy Clusters." Scientific American, December 1998.
http://atropos.as.arizona.edu/aiz/teaching/a204/darkmat/SciAm98b.pdf
NASA Imagine the Universe, "The Hidden Lives of Galaxies" book. http://imagine.gsfc.nasa.gov/docs/teachers/galaxies/imagine/titlepage.html
NASA Imagine the Universe, Active Galaxies and Quasars. http://imagine.gsfc.nasa.gov/docs/science/know_l1/active_galaxies.html
NASA Imagine the Universe, The Hidden Lives of Galaxies poster. http://imagine.gsfc.nasa.gov/docs/teachers/galaxies/imagine/poster.jpg
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NASA/JPL GALEX. Galaxies and UV. http://www.galex.caltech.edu/SCIENCE/science.html
Science @NASA. What are Galaxies? How Do They Form and Evolve? http://science.hq.nasa.gov/universe/science/galaxies.html
SEDS.org, Galaxies. http://www.seds.org/messier/galaxy.html
Seeds, MA. "Stars & Galaxies (second edition)." Brooks/Cole, 2001.
Stephens, S. "Galaxy Sorting Handout."
NASA Imagine the Universe, "The Hidden Lives of Galaxies" book. http://imagine.gsfc.nasa.gov/docs/teachers/galaxies/imagine/titlepage.html
NASA Imagine the Universe, Active Galaxies and Quasars. http://imagine.gsfc.nasa.gov/docs/science/know_l1/active_galaxies.html
NASA Imagine the Universe, The Hidden Lives of Galaxies poster. http://imagine.gsfc.nasa.gov/docs/teachers/galaxies/imagine/poster.jpg
NASA/JPL Galaxy Evolution Explorer (GALEX). http://www.galex.caltech.edu/
NASA/JPL GALEX. Galaxies and UV. http://www.galex.caltech.edu/SCIENCE/science.html
Science @NASA. What are Galaxies? How Do They Form and Evolve? http://science.hq.nasa.gov/universe/science/galaxies.html
SEDS.org, Galaxies. http://www.seds.org/messier/galaxy.html
Seeds, MA. "Stars & Galaxies (second edition)." Brooks/Cole, 2001.
Stephens, S. "Galaxy Sorting Handout."
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University of Washington Astronomy Department. Lecture" "Galaxies: Classification, Formation, and Evolution." http://www.astro.washington.edu/larson/Astro101/LecturesBennett/Galaxies/galaxies.html
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Original article: Just How Many Galaxies Are in the Universe?
Copyright © 2023 HowStuffWorks, a division of InfoSpace Holdings, LLC, a System1 Company
WMAP Cosmology 101: What is the Universe Made of? http://map.gsfc.nasa.gov/m_uni/uni_101matter.html
Original article: Just How Many Galaxies Are in the Universe?
Copyright © 2023 HowStuffWorks, a division of InfoSpace Holdings, LLC, a System1 Company
'Rogue' star won't collide with our solar system in 29,000 years after all
Robert Lea
Tue, November 7, 2023
A white star zooms through space.
The solar system of the far future is safe from a run-in with a runaway dead star.
Last year, researchers looked at the trajectory of a rogue white dwarf star called WD 0810–353 with the Gaia space telescope and predicted that it was due for an encounter with our solar system in around 29,000 years. While this may seem a long time in human terms, it is a relatively short period cosmically speaking. For instance, the sun won't run out of hydrogen and swell out as a red giant for another 5 billion years, destroying Earth and the inner planets in the process.
While the sun's fate is likely sealed, new research has revealed that our planet at least won't have to worry about being decimated by the chaos caused by runaway white dwarf WD 0810–353 after all. In fact, the "rogue" star won't just miss the solar system; it might not even be headed our way at all, astronomers say.
"We found that the approach speed measured by the Gaia project is incorrect, and the close encounter predicted between WD0810–353 and the sun is actually not going to happen," astronomer Stefano Bagnulo said in a statement. "In fact, WD0810–353 may not even be moving towards the sun at all. That's one less cosmic hazard we have to worry about!"
Related: Fast-spinning white dwarf pulsar, the 2nd we've ever discovered, sheds light on how stars evolve
What did Gaia get wrong?
Gaia is a space telescope that is currently building an extraordinarily precise three-dimensional map of more than a billion stars throughout our Milky Way galaxy. It does this by precisely measuring the positions of stars and tracking changes in these positions by returning this "slice" of the sky and observing it again to see what has changed.
In 2022, astronomers Vadim Bobylev and Anisa Bajkova analyzed the vast Gaia dataset, searching for stars that appear to be heading toward the solar system. This led them to WD 0810–353, a white dwarf star — a type of dense stellar remnant left behind when stars with masses similar to the sun die.
Our own sun will become a white dwarf about a billion years after its destructive red giant spell when the swelled outer layers of the sun will cool and move away, leaving behind a smoldering core.
WD 0810–353 might offer a preview of what the sun will look like at that time when it comes to within around half a light-year of the solar system, about 31,000 times the distance between Earth and the sun.
While this seems like anything but a close encounter, it is close enough that the gravitational influence of WD 0810–353 could disturb the Oort cloud — a body of comets and other icy bodies at the edge of the solar system.
The Oort cloud is located between 2,000 and 100,000 times the distance between Earth and the sun from the solar system's central star. When the cloud gets shuffled by passing stars like WD 0810–353, the star's gravity could send some of these loosely gravitationally bound icy bodies plummeting toward the inner solar system and Earth.
So, what happened with the observations of this rogue white dwarf? What made astronomers think it was heading our way, and how do we know it probably isn't?
a map of the solar system showing distant bodies beyond Neptune
A magnetic mix-up
When making its observations of WD 0810–353, it turns out Gia missed something important and unusual about this white dwarf. It has a strangely large magnetic field.
"Unusually, this old white dwarf also has a huge magnetic field," explains Eva Villaver, an astronomer at the Astrobiology Center in Spain and co-author of the study. "In astronomy, magnetic fields are crucial to understanding many physical aspects of a star, and not considering them can lead to misinterpretations of physical phenomena."
The astronomers had determined WD 0810–353 was heading toward us by calculating the white dwarf's radial velocity — the velocity of an object along the line of sight from the observer to that object. This is done by looking at the spectrum of light being emitted by the star and then splitting that down into constituent wavelengths that make up that light.
If a star is moving away us, that scrunches up wavelengths, which has the effect of shifting the light down to the red end of the electromagnetic spectrum, a phenomenon known as redshift. If a star is moving toward us, however, the wavelength of light it emits is stretched and moves toward the blue end and is described as being "blueshifted."
The thing is that magnetic fields can also affect the spectrum of light from a star, dead or not, by splitting spectral lines and shifting lines to other wavelengths.
Crisis averted…
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To determine if this was the case with WD 0810–353, Bagnulo turned to the Very Large Telescope (VLT) located in northern Chile, and in particular, an instrument called the FOcal Reducer and low dispersion Spectrograph 2 (FORS2).
FORS2 let the team get a highly accurate picture of the spectra of WD 0810–353 and see if its intense magnetic field was messing with Gaia. This is possible because light waves usually oscillate in all directions, but when introduced to a magnetic field, they start to oscillate in a preferred direction — becoming "polarized."
Using polarized light from this white dwarf, the team modeled the magnetic field of the dead star and found its trajectory and velocity could actually be the result of a strong magnetic field. That means the solar system is likely safe from this particular rogue white dwarf.
The team's research is published in the Astrophysical Journal.
What Would Happen if a Solar Storm Hit Earth?
Laurie L. Dove, Desiree Bowie
Wed, November 8, 2023
Solar flares, which can impact Earth's environment, are magnetic explosions on the sun's surface.
DrPixel / Getty Images
Contrary to its serene appearance from Earth, the sun is a hub of intense activity. The fiery dynamic star at the center of our solar system frequently releases powerful bursts of energy and charged particles, known as solar storms.
One might wonder: What would happen if a particularly strong solar storm hit Earth?
These solar outbursts, when they reach our planet, not only paint the sky with breathtaking displays known as auroras but can also interfere with modern technology. Let's take a look at the science behind this unique form of space weather and its potential impact.
Contrary to its serene appearance from Earth, the sun is a hub of intense activity. The fiery dynamic star at the center of our solar system frequently releases powerful bursts of energy and charged particles, known as solar storms.
One might wonder: What would happen if a particularly strong solar storm hit Earth?
These solar outbursts, when they reach our planet, not only paint the sky with breathtaking displays known as auroras but can also interfere with modern technology. Let's take a look at the science behind this unique form of space weather and its potential impact.
What Is a Solar Storm?
A solar storm involves disturbances on the sun, such as solar flares and coronal mass ejections (CMEs), which release streams of energetic particles and massive bubbles of gas threaded with magnetic field lines into space.
These events can impact Earth and other planets when the particles interact with planetary magnetic fields and atmospheres.
These storms often follow sunspot cycles and can propel particles toward Earth at high speeds. When these particles collide with Earth's magnetic field, they can cause geomagnetic storms that result in beautiful auroras, also known as the northern and southern lights.
However, they can also pose risks to satellites, power grids and communication networks. The intensity of solar storms can vary, with some being minor and causing little effect, while others can be powerful enough to disrupt Earth's magnetosphere and ionosphere, leading to significant technological disturbances.
Ranking the Intensity of Solar Storms
The NOAA Space Weather Scales is a standardized system developed by the National Oceanic and Atmospheric Administration (NOAA) to rank and categorize the severity of space weather events, specifically geomagnetic storms.
Much like the scales used for tornadoes or hurricanes, NOAA's scale provides a clear framework for understanding the potential impact of these celestial disturbances on Earth and its technological infrastructure.
The scale ranges from 1 (minor) to 5 (extreme) and is based on the potential impact on power systems, satellite operations and other technological systems, as well as the visibility of auroras at specific geographical latitudes.
By using this scale, NOAA aims to provide clear warnings and timely information to stakeholders, ensuring preparedness and mitigation during significant solar events.
Now let's go back in time to the 19th century to explore the largest solar storm ever recorded and its impact on Earth.
The Carrington Event
It started like any other morning. Richard Carrington climbed the steps leading to an amateur observatory housed at his rural London estate, cranked open the shuttered dome and aimed a large brass telescope at a clear, blue sky.
He recorded the moment — 11:18 a.m., Sept. 1, 1859 — and then, as the sun came into view, began to sketch a group of large sunspots.
As he did, two points of light emerged, intensified and bloomed right before his eyes. Five minutes later, the blinding flares were gone. Although he didn't yet realize it, Carrington had witnessed what would become known as the largest solar flare in modern history.
The white-light solar flare, which someday would bear Carrington's name, was actually a magnetic explosion on the sun's surface.
It was so powerful that it briefly outshone the sun and, within a few hours, caused brilliant red, green and purple lights in the sky to erupt all over Earth (such light shows are colorful and common side effects of solar flares with coronal mass ejections).
It also supercharged telegraph cables that shocked operators, set telegraph paper afire and, in some cases, transmitted messages even when the lines were disconnected from their batteries.
What Will Happen if a Large-scale Solar Flare Hits Earth?
Although there's still evidence of solar material erupting frequently on the sun, none have reached the magnitude of the 1859 event. But what if one did?
We have some idea based on lesser solar flare explosions that produced clouds of charged particles that have crashed into Earth's magnetic field, causing the field to waver in what researchers call a "geomagnetic storm." [source: NOAA]
In February 2011, for example, a solar storm interrupted GPS signals for several minutes, which could potentially have spelled disaster for commercial airplanes or ships relying on GPS guidance systems to land or dock during that time. [source: NASA]
Over a decade afterward, on April 21, 2023, a powerful solar event sent a fast-moving burst of plasma toward Earth, causing a severe geomagnetic storm two days later.
This storm disrupted power, communication systems and satellite functions. It also created brilliant auroras. Monitored by NOAA's DSCOVR spacecraft, this was the third major storm of its kind in the current solar cycle, following similar events in 2021 and earlier in 2023.
Tech Interference
If a "Carrington-sized" solar flare were to hit Earth today, it would emit X-rays and ultraviolet light, which would reach Earth's atmosphere and interfere with electronics, as well as radio and satellite signals.
It would also cause a solar radiation storm, which could potentially be deadly to astronauts not fully equipped with protective gear and unprotected by Earth's atmosphere.
Finally, a cloud of charged particles (that coronal mass ejection we mentioned earlier) would bump against Earth's magnetic field. Such an event would mean outages that would decommission everything from cell phones and computers to automobiles and airplanes. Cities would lose power for weeks and, potentially, months — and many activities necessary to daily life would no longer be possible.
Take a trip to refuel at a gas station, for example. Simply using a credit or debit card to pay for a few gallons of gas requires a satellite transaction, and creating one would no longer be possible.
The potential consequences of a large-scale solar flare hitting Earth have scientists scrambling to develop an early warning system and new solar flare detection methods, much like their predecessors once learned to forecast deadly tornadoes and other weather events. Someday, we might just have solar flare warnings alongside hurricane warnings and thunderstorm watches.
How to Prepare for Extreme Solar Storms
As the old saying goes, if you stay ready, you don't have to get ready. If you're concerned about how to safely make it through a massive solar storm, here are some steps you can take for peace of mind:
Stay informed: Follow space weather forecasts from official sources like the NOAA Space Weather Prediction Center to stay updated on solar activity.
Emergency kit: Have an emergency preparedness kit ready with essentials like water, nonperishable food, a flashlight, batteries, a first-aid kit and cash, in case of prolonged power outages from downed electricity grids.
Protect electronics: Use surge protectors for electronic devices and consider unplugging sensitive electronics during severe solar storms to prevent damage from power surges.
Data backups: Regularly back up important data from computers and mobile devices to cloud services or external hard drives.
Communication plan: Have a plan for alternative communication, such as text messaging or using a satellite phone, as cell towers and landlines could be affected.
Alternate power: Consider investing in alternative power sources such as solar-powered chargers or generators for essential power needs.
Vehicle safety: If you rely on GPS navigation, keep paper maps in your vehicle and familiarize yourself with alternative routes.
Home preparations: If you have a home solar panel system, check with the installer about protective measures against geomagnetically induced currents.
This article was updated in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.
Lots More Information
Sources
Bell, Trudy, and Tony Phillips. "A Super Solar Flare." NASA. May 6, 2008. (April 10, 2015) http://science.nasa.gov/science-news/science-at-nasa/2008/06may_carringtonflare/
Lovett, Richard. "What if the Biggest Solar Storm on Record Happened Today?" National Geographic. March 4, 2011. (April 10, 2015) http://news.nationalgeographic.com/news/2011/03/110302-solar-flares-sun-storms-earth-danger-carrington-event-science/
Darren Orf
Tue, November 7, 2023
How a Kilonova Explosion Could End Life on EarthUniversity of Warwick/Mark Garlick, CC BY 4.0 , via Wikimedia Commons
Analyzing data from GW170817, the first kilonova ever discovered, scientists at the University of Illinois Urbana-Champaign discerned what would happen if an explosion like that ever occurred in our cosmic backyard.
According to the study, the greatest threat would take the form of a bubble of cosmic rays that would ionize the Earth’s ozone and make the planet uninhabitable for thousands of years.
Luckily, this is an unlikely scenario, as the binary neutron mergers that produce kilonovas are extremely rare. One has yet to be found in our galaxy.
Space is an inhospitable place—for people and planets. Stars go supernova, black holes swallow basically everything, and rogue planets careen through the galaxy, ready to dramatically disrupt stellar systems. Now, scientists are adding another doomsday scenario to this world-ending nightmare list—kilonovas.
According to scientists at the University of Illinois Urbana-Champaign, a kilonova—an explosion caused by two colliding neutron stars—located within 35 light years of Earth could bathe the planet in cosmic rays and exterminate life for thousands of years. Scientists analyzed data from GW170817, the first kilonova ever discovered, and uploaded the results of that work last week to the preprint server arXiv.
“As the awareness and understanding of powerful cosmic transients have grown, so also has the realization of their dangers,” the paper reads. “We found that cosmic rays are the most threatening emissions and are potentially lethal…even if it never induced a mass extinction, a nearby kilonova event would be visible on Earth. It would likely disrupt technology soon after the merger and remain bright in the sky for over a month.”
Cosmic rays are energetically charged particles that bombard the Earth at all times—both from our own Sun and from distant sources throughout the universe. The cosmic ray bubble that would issue from the center of a kilonova explosion could impact planets 36 light years away. And because cosmic rays hang around longer than other types of rays rays, they’d leave planets lifeless for thousands of years.
But cosmic rays are only one threat posed by these giant space explosions. While it's less likely to hit us, the most intense threat is the two jets of gamma radiation that emitted from the kilonova. If caught in a jet’s path, the gamma rays would ionize our ozone and leave our planet susceptible to UV radiation, dooming Earth from as far as 297 light years away.
And if Earth is not in the path of this cue ball of doom, the kilonova has other options. It also issues a “cocoon” of gamma radiation in all directions that would affect planets up to 13 light years away. Damage from this cocoon could take the ozone four years to recover from—more than enough time for UV radiation to wreak havoc on the planet. Neutron star mergers also create an “X-ray afterglow” when gamma radiation hits the interstellar medium, but planets would need to be within 16 light years to be affected by that particular effect.
Thankfully, this specific cosmic doomsday scenario is highly improbable. For one, binary neutron mergers are extremely rare. Scientists estimate that for 100 billion stars, only 10 of them are destined to become binary neutron star mergers. And of the handful of kilonovae we’ve discovered, none of them are in our galaxy.
But while we might be out of the “death by kilonova” woods, dangers lurk around every cosmic corner. Even our own life-giving Sun could put us in danger. The universe is a perilous place, and we’re just trying to live in it.
