It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Sunday, February 25, 2024
SPACE
Dramatic Image Reveals How Much The Sun Has Changed in Two Years
The solar cycle has been reasonably well understood since 1843 when Samuel Schwabe spent 17 years observing the variation of sunspots. Since then, we have regularly observed the ebb and flow of the sunspots cycle every 11 years.
More recently ESA's Solar Orbiter has taken regular images of the Sun to track the progress as we head towards the peak of the current solar cycle.
Two recently released images from February 2021 and October 2023 show how things are really picking up as we head toward solar maximum.
Startling differences in sun activity as captured by the Solar Orbiter in 2021 (top) and 2023 (bottom. (ESA & NASA/Solar Orbiter/EUI Team)
The Sun is a great big ball of plasma, electrically charged gas, which has the amazing property that it can move a magnetic field that may be embedded within. As the Sun rotates, the magnetic field gets dragged around with it but, because the Sun rotates faster at the equator than at the poles, the field lines get wound up tighter and tighter.
Under this immense stressing, the field lines occasionally break, snap or burst through the surface of the Sun and when they do, we see a sunspot. These dark patches on the visible surface of the Sun are regions where denser concentrations of solar material prohibit heat flow to the visible surface giving rise to slightly cooler, and therefore darker patches on the Sun.
A collage of new solar images captured by the Inouye Solar Telescope, which is a small amount of solar data obtained during the Inouye's first year of operations throughout its commissioning phase. Images include sunspots and quiet regions of the Sun, known as convection cells. (NSF/AURA/NSO)
The slow rotation of the Sun and the slow but continuous winding up of the field lines means that sun spots become more and more numerous as the field gets more distorted. Observed over a period of years the spots seem to slowly migrate from the polar regions to the equatorial regions as the solar cycle progresses.
To try and help understand this complex cycle and unlock other mysteries of the Sun, the European Space Agency launched its Solar Orbiter on 10 February 2020. Its mission to explore the Sun's polar regions, understand what drives the 11 year solar cycle and what drives the heating of the corona, the outer layers of the Sun's atmosphere.
Images from Solar Orbiter have been released that show closeups of the Sun's visible surface, the photosphere as it nears peak of solar activity.
At the beginning of the cycle, at solar minimum in 2019, there was relatively little activity and only a few sunspots. Since then, things have been slowly increasing. The image from February 2021 showed a reasonably quiet Sun but an image taken in October last year shows that things are, dare I say, hotting up!
The maximum of this cycle is expected to occur in 2025 which supports theories that the period of maximum activity could arrive a year earlier.
Understanding the cycle is not just of whimsical scientific interest, it is vital to ensure we minimize damage to ground based and orbiting systems but crucially understand impact on life on Earth.
The Belt At The Edge Of The Solar System Is Larger Than We Thought
New observations suggest that the Kuiper Belt might extend even further out than we thought it did.
DR. ALFREDO CARPINEO
Ok, the Kuiper belt is certainly not this busy – but it might be busier than previously thought! Image Credit: ESO/M. Kornmesser
Beyond the orbits of the eight planets in our Solar System, several distant objects make up the Kuiper Belt. The extent of this region has been estimated based on the discovery of such objects – but new observations are implying that it goes further out than previously thought.
NASA’s New Horizons spacecraft visited the most famous Kuiper Belt Object (KBO), the dwarf planet Pluto. It then flew by a small KBO called Arrokoth, and is now traveling across the belt. One of its instruments, the Venetia Burney Student Dust Counter (SDC), measures levels of dust as the spacecraft travels.
Named after the person that named Pluto, the SDC was expected to see a drop in the amount of dust it picked up. The dust comes from collisions between KBOs, asteroids, and comets, as well as KBOs' bombardment from interstellar dust. Observations from Earth consider the belt to extend to 50 times the distance between Earth and the Sun (or one Astronomical Unit, AU).
But New Horizons is at 55 AU, and it is still going strong.
The team's analysis suggests that the belt might go all the way to 80 AU or maybe even further, implying that KBOs might also extend further. If that is indeed the case, there are many undiscovered objects in the Kuiper Belt.
“New Horizons is making the first direct measurements of interplanetary dust far beyond Neptune and Pluto, so every observation could lead to a discovery,” lead author of the new study Alex Doner from the University of Colorado Boulder, who serves as SDC lead, said in a statement. “The idea that we might have detected an extended Kuiper Belt — with a whole new population of objects colliding and producing more dust – offers another clue in solving the mysteries of the solar system’s most distant regions.”
The team is not discounting alternatives – maybe the dust is being pushed by sunlight to more distant regions of the solar system, messing with the expected measurements. Or maybe New Horizons has encountered short-lived ice that is adding a temporary extra amount of dust when only little is present. It’s possible, but given the difficulties of finding KBOs, it's not surprising that we have not found a large population of them.
“These new scientific results from New Horizons may be the first time that any spacecraft has discovered a new population of bodies in our solar system,” said Alan Stern, New Horizons principal investigator from the Southwest Research Institute in Boulder. “I can’t wait to see how much farther out these elevated Kuiper Belt dust levels go.”
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Feb 24, 2024, This image of Uranus from NIRCam (Near-Infrared Camera) on NASA’s James Webb Space Telescope.
NASA, ESA, CSA, STSCI
Scientists have discovered three new moons in the solar system, including two around Neptune and the smallest moon of Uranus found in over 20 years.
“The three newly discovered moons are the faintest ever found around these two ice giant planets using ground-based telescopes,” said Scott S. Sheppard at the Carnegie Institution for Science, who used the Magellan telescopes at Carnegie Science’s Las Campanas Observatory in Chile. “It took special image processing to reveal such faint objects,” he said. The discoveries required taking dozens of five-minute exposures over several hours.
Here’s what Sheppard found:
S/2023 U1, 8 kilometers in size, which takes 680 days to orbit Uranus. S/2002 N5, 23 kilometers in size, which takes almost 9 years to orbit Neptune. S/2021 N1, 14 kilometers, which takes almost 27 years to orbit Neptune.
The discovery image of the new Uranian moon S/2023 U1 using the Magellan telescope on November 4, 2023 ... [+]SCOTT SHEPPARD
New Moon At Uranus
First spotted on November 4, Sheppard also found the tiny moon S/2023 U1 in images he’s taken in 2021 using the Magellan telescope and the Subaru telescope in Hawaii. Its discovery brings the ice giant planet’s total moon count to 28.
The six largest moons around the seventh planet from the sun are Ariel, Umbriel, Titania, Oberon, Puck, and Miranda, the first four of which are suspected to host underground oceans. A proposed Uranus orbiter on a NASA flagship mission would likely concentrate on finding out if those moons may be ocean worlds.
As with its existing moons, S/2023 U1 will eventually be named after characters from the works of William Shakespeare and Alexander Pope. However, Uranus is the only planet in the solar system named after the Greek god of the sky (the father of Saturn and the grandfather of Jupiter). Neptune’s Nymphs
As with Neptune’s existing moons—which also include Naiad, Thalassa, Despina, Galatea and Proteus—its two newly discovered moons will be named after the Nereid sea nymphs in Greek mythology.
It’s much harder for planetary astronomers to complete an inventory of moons at outer planets Neptune and Uranus than at planets closer to Earth. All moons of about 2 kilometers in size have been found at Jupiter, while at Saturn it’s 3 kilometers. However, for Uranus and Neptune, it’s between 8 and 14 kilometers, respectively. That’s partly because Jupiter and Saturn have been visited multiple times by spacecraft, while Uranus and Neptune have only been visited once by NASA’s Voyager 2 probe in 1986 and 1989, respectively.
However, a rare planetary alignment in the 2030s may provide a window to visit Uranus and Neptune after a slingshot around Jupiter—though any spacecraft would need to leave Earth by the early 2030s to get to Uranus by the 2040s.
I'm an experienced science, travel and photography journalist, a stargazer and eclipse-chaser, writing about exploring the night sky, total solar eclipses, moon-gazing, astro-travel, astronomy and space exploration. I also edit SmartTelescopeReviews.com and I'm the author of "A Stargazing Program for Beginners: A Pocket Field Guide" (Springer, 2015). I write for Space.com, Live Science, Sky & Telescope magazine, BBC Sky At Night magazine, The Planetary Society, New Scientist, Travel+Leisure, T3, the South China Morning Post and Digital Camera World.
Finding life on Saturn's moon Titan may be more difficult than previously thought
But that doesn't mean it's impossible, and there are plenty more moons to search
As it glanced around the Saturn system one final time, NASA's Cassini spacecraft captured this view of the planet's giant moon Titan. These views were obtained by Cassini's narrow-angle camera on Sept. 13, 2017. They are among the last images Cassini sent back to Earth. (NASA)
"Are we alone?" It's the age-old question about life in the universe, one that astrobiologists and astronomers around the world are trying to answer.
While Earth is the only planet in our solar system that has an abundance of life, astronomers and space agencies are looking in our own backyard for signs that we are not alone. And many believe that the best places to search are the icy moons around two of the biggest planets, Jupiter and Saturn.
Currently, there are seven bodies in the outer solar system that are believed to have oceans beneath their crust: two of Saturn's moons, Titan and Enceladus; three of Jupiter's moons, Europa, Ganymede, and Callisto; one of Neptune's moons, Triton; and finally, Pluto.
They may have water, but do they have the chemical ingredients to create — and sustain — life?
The study aimed to answer the question: If something slammed into Titan, creating an impact crater melt, could organics on the surface make it down to the ocean where they could support life?
The answer, unfortunately, was no.
"We found that even in the most optimistic scenario we could think of the amount of organics that makes it down there is quite small," said Catherine Neish, lead author of the study and an Earth sciences professor at Western University.
"So small that either life would be very difficult to be sustained over time, or in a slightly more optimistic scenario, maybe it's there, but it's so minimal that we need better instruments in order to detect such a very low level of activity.
"So it is not the thriving biosphere that I think we had hoped for."
However, that doesn't necessarily mean that the search for life on other icy moons — or even Titan — is dead in the water.
Shannon MacKenzie, a planetary scientist at Johns Hopkins University, said she believes that it was a very good study. However, she notes that there's a lot about Titan we just don't know.
"It's really hard to to conduct studies like this, because we don't, first of all, know what's on the surface of Titan," she said. "So you have to make an assumption about what kind of organics are mixing in that impact melt. The laboratory–based or analogues that we have studied well here on Earth, are just that — they're analogues. They're our best guess of what sitting on the surface."
Another issue for astrobiologists is that they don't know how long Titan has had its thick atmosphere that transports organics down to the surface.
Other moons, other chances at finding life
While Neish is skeptical about subsurface life existing on icy moons, she's not ruling it out entirely on Titan.
"On Earth, we don't see life just spread evenly out throughout the ocean: it's in these like, micro–habitats that maybe cluster near the ocean floor.... It's not just evenly distributed. And so I'm hopeful that maybe on Titan, maybe the organics don't get evenly distributed throughout the entire ocean, maybe they stay trapped near the ice–ocean interface."
There is also the possibility that something is occurring beneath the surface, hundreds of kilometres below the ice that could sustain it. She said there is an upcoming paper that will discuss that prospect.
And, of course, there are other places in the solar system that are good candidates, including two of the most talked about: Enceladus and Europa.
Missions to moons
In 2005, the European Space Agency's Huygens spacecraft (part of the joint NASA-ESA Cassini-Huygens mission) gave us the first glimpse of what lay beneath the thick, orange-yellow atmosphere of Titan — and it was a surprise. As it descended, it captured large bodies of lakes — later confirmed to be made of hydrocarbons — and, once on the ground, smooth pebbles.
That has been the only mission to the surface of another moon. And while the data collected was invaluable, it was limited.
This image was returned on Jan. 14, 2005, by ESA's Huygens probe during its successful descent to land on Titan. The surface with pebble-sized objects is darker than originally expected, consisting of a mixture of water and hydrocarbon ice. There is also evidence of erosion at the base of these objects, indicating possible fluvial activity. (ESA/NASA/JPL/University of Arizona)
But that's about to change.
NASA plans to send a rotorcraft mission — called Dragonfly — that will fly around Titan gathering critical information that will help astronomers and astrobiologists further study the moon and its composition (Neish is the astrobiology lead for Dragonfly, and MacKenzie is also part of the team).
Both scientists are anxiously awaiting the launch, set for some time in 2028.
"We're going with Dragonfly to really understand how organic chemistry can evolve in these other environments in the solar system to get a better understanding of what happened on our own planet before life took over and rewrote the chemistry, the chemical history," MacKenzie said.
The Dragonfly rotorcraft lander, shown here in an artist's rendering of the mission concept, will land on Saturn's moon Titan and then make multiple flights to explore diverse locations as it characterizes the habitability of the ocean world's environment. (NASA/Johns Hopkins APL/Steve Gribben)
And in October, the Europa Clipper will launch to its namesake moon that orbits Jupiter. Along with Saturn's moon Enceladus, it is considered a promising place to look for life: It spews particles into space from fissures in its surface ice.
MacKenzie said she's excited about the upcoming mission and that, with so many unique moons in our solar system, there are plenty of places to search for life.
"We have these different flavours of ocean worlds at our disposal, which I think is why we need a whole fleet of missions to go explore them all because they're different," she said.
Based in Toronto, Nicole covers all things science for CBC News. As an amateur astronomer, Nicole can be found looking up at the night sky appreciating the marvels of our universe. She is the editor of the Journal of the Royal Astronomical Society of Canada and the author of several books. In 2021, she won the Kavli Science Journalism Award from the American Association for the Advancement of Science for a Quirks and Quarks audio special on the history and future of Black people in science. You can send her story ideas at Nicole.Mortillaro@cbc.ca.
Image of the Sun from Solar Orbiter (left Feb 2021 and right Oct 2023). (ESA & NASA/Solar Orbiter/EUI Team)
Startling differences in sun activity as captured by the Solar Orbiter in 2021 (top) and 2023 (bottom. (ESA & NASA/Solar Orbiter/EUI Team)
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