SPACE/COSMOS
As NASA missions study interstellar comet, Hubble makes size estimate
image:
This is a Hubble Space Telescope image of the interstellar comet 3I/ATLAS. Hubble photographed the comet on July 21, 2025, when the comet was 277 million miles from Earth. Hubble shows that the comet has a teardrop-shaped cocoon of dust coming off its solid, icy nucleus. Because Hubble was tracking the comet moving along a hyperbolic trajectory, the stationary background stars are streaked in the exposure.
view moreCredit: NASA, ESA, David Jewitt (UCLA); Image Processing: Joseph DePasquale (STScI)
A team of astronomers has taken the sharpest-ever picture of the unexpected interstellar comet 3I/ATLAS using the crisp vision of NASA’s Hubble Space Telescope. Hubble is one of many missions across NASA’s fleet of space telescopes slated to observe this comet, together providing more information about its size and physical properties. While the comet poses no threat to Earth, NASA’s space telescopes help support the agency's ongoing mission to find, track, and better understand near-Earth objects.
Hubble’s observations allow astronomers to more accurately estimate the size of the comet’s solid, icy nucleus. The upper limit on the diameter of the nucleus is 3.5 miles (5.6 kilometers), though it could be as small as 1,000 feet (320 meters) across, researchers report. Though the Hubble images put tighter constraints on the size of the nucleus compared to previous ground-based estimates, the solid heart of the comet presently cannot be directly seen, even by Hubble. Observations from other NASA missions including the James Webb Space Telescope, TESS (Transiting Exoplanet Survey Satellite), and the Neil Gehrels Swift Observatory, as well as NASA’s partnership with the W.M. Keck Observatory, will help further refine our knowledge about the comet, including its chemical makeup.
Hubble also captured a dust plume ejected from the Sun-warmed side of the comet, and the hint of a dust tail streaming away from the nucleus. Hubble’s data yields a dust-loss rate consistent with comets that are first detected around 300 million miles from the Sun. This behavior is much like the signature of previously seen Sun-bound comets originating within our solar system.
The big difference is that this interstellar visitor originated in some other solar system elsewhere in our Milky Way galaxy.
3I/ATLAS is traveling through our solar system at a staggering 130,000 miles (209,000 kilometers) per hour, the highest velocity ever recorded for a solar system visitor. This breathtaking sprint is evidence that the comet has been drifting through interstellar space for many billions of years. The gravitational slingshot effect from innumerable stars and nebulae the comet passed added momentum, ratcheting up its speed. The longer 3I/ATLAS was out in space, the higher its speed grew.
“No one knows where the comet came from. It’s like glimpsing a rifle bullet for a thousandth of a second. You can't project that back with any accuracy to figure out where it started on its path,” said David Jewitt of the University of California, Los Angeles, science team leader for the Hubble observations.
The paper will be published in The Astrophysical Journal Letters. It is already available on Astro-ph.
New Evidence for Population of Wandering Space Relics
“This latest interstellar tourist is one of a previously undetected population of objects bursting onto the scene that will gradually emerge,” said Jewitt. “This is now possible because we have powerful sky survey capabilities that we didn't have before. We've crossed a threshold."
This comet was discovered by the NASA-funded Asteroid Terrestrial-impact Last Alert System (ATLAS) on July 1, 2025, at a distance of 420 million miles from the Sun. ATLAS is an asteroid impact early warning system developed by the University of Hawai’i.
In the meantime, other NASA missions will provide new insight into this third interstellar interloper, helping refine our understanding of these objects for the benefit of all. 3I/ATLAS should remain visible to ground-based telescopes through September, after which it will pass too close to the Sun to observe, and is expected to reappear on the other side of the Sun by early December.
The Hubble Space Telescope has been operating for more than three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
To learn more about Hubble, visit: https://science.nasa.gov/hubble
Journal
The Astrophysical Journal Letters
Subject of Research
Not applicable
Article Title
Hubble Space Telescope Observations of the Interstellar Interloper 3I/ATLAS
'Most massive black hole ever discovered' is detected
Royal Astronomical Society
image:
The Cosmic Horseshoe gravitational lens. The newly discovered ultramassive blackhole lies at the centre of the orange galaxy. Far behind it is a blue galaxy that is being warped into the horseshoe shaped ring by distortions in spacetime created by the immense mass of the foreground orange galaxy.
view moreCredit: NASA/ESA
Astronomers have discovered potentially the most massive black hole ever detected.
The cosmic behemoth is close to the theoretical upper limit of what is possible in the universe and is 10,000 times heavier than the black hole at the centre of our own Milky Way galaxy.
It exists in one of the most massive galaxies ever observed – the Cosmic Horseshoe – which is so big it distorts spacetime and warps the passing light of a background galaxy into a giant horseshoe-shaped Einstein ring.
Such is the enormousness of the ultramassive black hole’s size, it equates to 36 billion solar masses, according to a new paper published today in Monthly Notices of the Royal Astronomical Society.
It is thought that every galaxy in the universe has a supermassive black hole at its centre and that bigger galaxies host bigger ones, known as ultramassive black holes.
“This is amongst the top 10 most massive black holes ever discovered, and quite possibly the most massive,” said researcher Professor Thomas Collett, of the University of Portsmouth.
“Most of the other black hole mass measurements are indirect and have quite large uncertainties, so we really don't know for sure which is biggest. However, we’ve got much more certainty about the mass of this black hole thanks to our new method.”
Researchers detected the Cosmic Horseshoe black hole using a combination of gravitational lensing and stellar kinematics (the study of the motion of stars within galaxies and the speed and way they move around black holes).
The latter is seen as the gold standard for measuring black hole masses, but doesn't really work outside of the very nearby universe because galaxies appear too small on the sky to resolve the region where a supermassive or ultramassive black hole lies.
Adding in gravitational lensing helped the team “push much further out into the universe”, Professor Collett said.
“We detected the effect of the black hole in two ways – it is altering the path that light takes as it travels past the black hole and it is causing the stars in the inner regions of its host galaxy to move extremely quickly (almost 400 km/s).
“By combining these two measurements we can be completely confident that the black hole is real.”
Lead researcher, PhD candidate Carlos Melo, of the Universidade Federal do Rio Grande do Sul (UFRGS) in Brazil, added: “This discovery was made for a 'dormant' black hole – one that isn’t actively accreting material at the time of observation.
“Its detection relied purely on its immense gravitational pull and the effect it has on its surroundings.
“What is particularly exciting is that this method allows us to detect and measure the mass of these hidden ultramassive black holes across the universe, even when they are completely silent.”
The Cosmic Horseshoe black hole is located a long way away from Earth, at a distance of some 5 billion light-years.
“Typically, for such remote systems, black hole mass measurements are only possible when the black hole is active,” Melo said. “But those accretion-based estimates often come with significant uncertainties.
“Our approach, combining strong lensing with stellar dynamics, offers a more direct and robust measurement, even for these distant systems.”
The discovery is significant because it will help astronomers understand the connection between supermassive black holes and their host galaxies.
“We think the size of both is intimately linked,” Professor Collett added, “because when galaxies grow they can funnel matter down onto the central black hole.
“Some of this matter grows the black hole but lots of it shines away in an incredibly bright source called a quasar. These quasars dump huge amounts of energy into their host galaxies, which stops gas clouds condensing into new stars.”
Our own galaxy, the Milky Way, hosts a 4 million solar mass black hole. Currently it's not growing fast enough to blast out energy as a quasar but we know it has done in the past, and it may will do again in the future.
The Andromeda Galaxy and our Milky Way are moving together and are expected to merge in about 4.5 billion years, which is the most likely time for our supermassive black hole to become a quasar once again, the researchers say.
An interesting feature of the Cosmic Horseshoe system is that the host galaxy is a so-called fossil group.
Fossil groups are the end state of the most massive gravitationally bound structures in the universe, arising when they have collapsed down to a single extremely massive galaxy, with no bright companions.
“It is likely that all of the supermassive black holes that were originally in the companion galaxies have also now merged to form the ultramassive black hole that we have detected,” said Professor Collett.
“So we're seeing the end state of galaxy formation and the end state of black hole formation.”
The discovery of the Cosmic Horseshoe black hole was somewhat of a serendipitous discovery. It came about as the researchers were studying the galaxy’s dark matter distribution in an attempt to learn more about the mysterious hypothetical substance.
Now that they’ve realised their new method works for black holes, they hope to use data from the European Space Agency’s Euclid space telescope to detect more supermassive black holes and their hosts to help understand how black holes stop galaxies forming stars.
ENDS
Another image of the Cosmic Horseshoe, but with the pair of images of a second background source highlighted. The faint central image forms close to the black hole, which is what made the new discovery possible.
Credit
NASA/ESA/Tian Li(University of Portsmouth)
Images & captions
Caption: The Cosmic Horseshoe gravitational lens. The newly discovered ultramassive blackhole lies at the centre of the orange galaxy. Far behind it is a blue galaxy that is being warped into the horseshoe shaped ring by distortions in spacetime created by the immense mass of the foreground orange galaxy.
Credit: NASA/ESA
Caption: Another image of the Cosmic Horseshoe, but with the pair of images of a second background source highlighted. The faint central image forms close to the black hole, which is what made the new discovery possible.
Credit: NASA/ESA/Tian Li(University of Portsmouth)
Further information
The paper ‘Unveiling a 36 Billion Solar Mass Black Hole at the Centre of the Cosmic Horseshoe Gravitational Lens’ by Carlos Roberto and Thomas Collett et al. has been published in Monthly Notices of the Royal Astronomical Society. DOI: 10.1093/mnras/staf1036.
Notes for editors
About the Royal Astronomical Society
The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.
The RAS organises scientific meetings, publishes international research and review journals, recognises outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.
The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.
Keep up with the RAS on Instagram, Bluesky, LinkedIn, Facebook and YouTube.
Journal
Monthly Notices of the Royal Astronomical Society
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
'Most massive black hole ever discovered' is detected
Article Publication Date
7-Aug-2025
An interstellar mission to a black hole? Astrophysicist thinks it’s possible.
Cell Press
image:
Although extremely challenging, astrophysicist Cosimo Bambi argues that an interstellar mission to send a tiny spacecraft to the nearest black hole is not out of reach.
view moreCredit: Event Horizon Telescope Collaboration.
It sounds like science fiction: a spacecraft, no heavier than a paperclip, propelled by a laser beam and hurtling through space at the speed of light toward a black hole, on a mission to probe the very fabric of space and time and test the laws of physics. But to astrophysicist and black hole expert Cosimo Bambi, the idea is not so far-fetched.
Reporting in the Cell Press journal iScience, Bambi outlines the blueprint for turning this interstellar voyage to a black hole into a reality. If successful, this century-long mission could return data from nearby black holes that completely alter our understanding of general relativity and the rules of physics.
“We don’t have the technology now,” says author Cosimo Bambi of Fudan University in China. “But in 20 or 30 years, we might.”
The mission hinges on two key challenges—finding a black hole close enough to target and developing probes capable of withstanding the journey.
Previous knowledge on how stars evolve suggests that there could be a black hole lurking just 20 to 25 light-years from Earth, but finding it won’t be easy, says Bambi. Because black holes don’t emit or reflect light, they are virtually invisible to telescopes. Instead, scientists detect and study them based on how they influence nearby stars or distort light.
“There have been new techniques to discover black holes,” says Bambi. “I think it’s reasonable to expect we could find a nearby one within the next decade.”
Once the target is identified, the next hurdle is getting there. Traditional spacecrafts, powered by chemical fuel, are too clunky and slow to make the journey. Bambi points to nanocrafts—gram-scale probes consisting of a microchip and light sail—as a possible solution. Earth-based lasers would blast the sail with photons, accelerating the craft to a third of the speed of light.
At that pace, the craft could reach a black hole 20 to 25 light-years away in about 70 years. The data it gathers would take another two decades to get back to Earth, making the total mission duration around 80 to 100 years.
Once the craft is near the black hole, researchers could run experiments to answer some of the most pressing questions in physics. Does a black hole truly have an event horizon, the boundary beyond which not even light can escape its gravitational pull? Do the rules of physics change near a black hole? Does Einstein’s theory of general relativity hold under the universe’s most extreme conditions?
Bambi notes that the lasers alone would cost around one trillion euros today, and the technology to create a nanocraft does not yet exist. But in 30 years, he says that costs may fall and technology may catch up to these bold ideas.
“It may sound really crazy, and in a sense closer to science fiction,” says Bambi. “But people said we’d never detect gravitational waves because they’re too weak. We did—100 years later. People thought we’d never observe the shadows of black holes. Now, 50 years later, we have images of two.”
###
This work was supported by funding from the National Natural Science Foundation of China.
iScience, Cosimo Bambi, “An interstellar mission to test astrophysical black holes.” https://www.cell.com/iscience/fulltext/S2589-0042(25)01403-8
iScience (@iScience_CP) is an open access journal from Cell Press that provides a platform for original research and interdisciplinary thinking in the life, physical, and earth sciences. The primary criterion for publication in iScience is a significant contribution to a relevant field combined with robust results and underlying methodology. Visit: http://www.cell.com/iscience. To receive Cell Press media alerts, contact press@cell.com.
Journal
iScience
Method of Research
Commentary/editorial
Subject of Research
Not applicable
Article Title
An interstellar mission to test astrophysical black holes
Article Publication Date
7-Aug-2025
Houston, we have a (sinus) problem: New Houston Methodist research examines astronaut nasal and sinus problems in outer space
Study has important implications as human spaceflight – including space tourism – becomes more prevalent
Houston Methodist
Sinus and congestion problems are more than just earthly annoyances, according to new research from Houston Methodist. A newly-published study reveals that a staggering 85% of astronauts aboard the International Space Station (ISS) experienced at least one nasal and sinus issue during their mission, which can significantly impact health.
Led by Dr. Masayoshi Takashima, chair of the Department of Otolaryngology – Head and Neck Surgery at Houston Methodist, the study analyzed 754 medical events from 71 astronauts between 2000-2019. In addition to 85% of astronauts reporting at least one nasal or sinus issue, 75% reported nasal congestion, which Takashima said is a common issue due to the lack of gravity pulling blood and other fluids downward.
And spacewalks made things worse. The pressure shifts from inside the cabin to the inside of a space suit led to increases in congestion, barotrauma (injuries to the ears or sinuses caused by changes in pressure) and Eustachian tube dysfunction, which can result in ear pain, muffled hearing, a feeling of fullness and other issues,
While the researchers found that astronauts often turned to over-the-counter medications to treat their symptoms, Takashima warned that these drugs may not have the same effects in outer space. He said the study has important implications as human spaceflight – including space tourism – become more prevalent.
“Astronauts are typically among the fittest individuals on the planet, yet this study shows that even they experience substantial sinonasal complaints in space,” Takashima said. “Imagine what happens when civilians with preexisting conditions start traveling to space.”
Takashima said preventative measures such as evaluation for nasal and sinus conditions and minor procedures to improve breathing may be needed for future astronauts. He also stressed the importance of future work to identify treatments that work well in space.
“This is about maintaining peak performance,” Dr. Takashima said. “If you’re not sleeping well because you can’t breathe, your cognitive function, reaction time and mission performance can suffer, and those things are absolutely critical in space.”
The open-access study was published in Laryngoscope Investigative Otolaryngology. Co-authors include Faizaan Khan, Koyal Ansingkar, Roshan Dongre, Samuel Razmi and Isuru Somawardana from Texas A&M School of Engineering Medicine, Zain Mehdi, Aatin Dhanda, Kayla Powell, Jeffrey Vrabec, Tariq Syed and Omar Ahmed from the Department of Otolaryngology – Head and Neck Surgery at Houston Methodist, and former astronaut David Hilmers from the Center for Space Medicine, Baylor College of Medicine.
For more information about Houston Methodist, visit our newsroom or our social media pages on X, Facebook, LinkedIn, Instagram and TikTok or our On Health and Leading Medicine blogs.
Journal
Laryngoscope Investigative Otolaryngology
Subject of Research
People
Article Title
Congestion and Sinonasal Illness in Outer Space: A Study on the International Space Station
Article Publication Date
5-Aug-2025
Space research: DLR gives the go-ahead for innovative space experiment from GSI Biophysics
image:
From left: Carola Hartel, Insa Schroeder (project manager), Katharina Block (YURI), Kim Knorr, Leonie Hartig.
view moreCredit: Photo: Smit Patel, YURI GmbH, Meckenbeuren
A piece of GSI/FAIR’s cutting-edge research is scheduled to be launched into space next year: the Biophysics department will be involved in one of the next scientific missions on the International Space Station (ISS) with a highly innovative research project. The “HippoBox” project was successfully reviewed by the German Space Agency at DLR and recently selected for participation in the CELLBOX-4 mission on the ISS. The aim of the project is to use brain organoids (“mini-brains”) to investigate neuroplastic changes in a specific area of the brain, the hippocampus – a question that is highly relevant for the medical preparation of future long-term missions in space.
On the campus of the GSI Helmholtzzentrum für Schwerionenforschung and the international accelerator center FAIR, which is being built here, detailed planning of the experiment has already begun and an important milestone has been reached: The specially developed hardware has been delivered and numerous preliminary tests are currently underway to gain further experience, for example with the suitability of the provided materials.
Dr. Insa Schroeder and her team from the GSI Biophysics Department, headed by Professor Marco Durante, are leading the “HippoBox” project. Important contributions also come from the DLR Institute of Aerospace Medicine, Dr. Christian Liemersdorf, and from the University of Applied Sciences Cologne, Professor Sherif El Sheikh. The start-up company Yuri is involved with mission support and technical infrastructure. "We are extremely delighted about DLR's positive decision and are proud to be able to make a contribution to space medicine research with HippoBox. The possibility of studying human brain organoids in real weightlessness (= microgravity) in space opens up promising new perspectives for health care during long-term stays in space. It is important to precisely investigate the mechanisms underlying possible neuroplastic changes in the hippocampus of astronauts, which could become a showstopper for long-term missions," explains Dr. Insa Schroeder.
The experiment aims to answer exciting scientific questions: Do neuronal structures and their function change in microgravity? Are there ways to counteract such changes in the brain's network? The research results could have a decisive influence on future strategies for maintaining the cognitive health of space travelers, but could also provide new insights for research into depression and dementia on Earth.
Dr. Schroeder and her team are currently working on the cell culture box itself, a kind of mini-incubator, barely the size of the palm of one's hand. It will contain the organoids and take care of their supply. “It's a miniature laboratory,” explains Dr. Insa Schroeder, describing the unique research prospects offered by participation in the ISS program: the miniature laboratory will be in operation on the ISS for a full 14 days in real microgravity. This results in significantly more extensive research possibilities with the organoids than, for example, a parabolic flight with an airplane or a flight with the DLR MAPHEUS research rocket, whose ballistic flight enable comparatively short periods of microgravity (seconds to minutes).
The “HippoBox” project focuses on the hippocampus, the central hub in the brain where information from various sensory systems flows together. This brain region is responsible for memory performance and learning behavior e.g. for processing movement coordination. This is also a crucial point for astronauts: They have to make important decisions in space, safely and rationally, and also maintain their motor skills, such as dexterity. At the same time, messenger substances (neurotransmitters) in the human brain are constantly moving between nerve cells, requiring a strong neuronal network. However, there are indications that the neuronal cells may drift further apart in microgravity, resulting in fewer contact points and a weaker neuronal network, similar to what is observed in people with dementia or depression.
The hippocampal organoids, which are currently being prepared at GSI/FAIR, should provide new insights and show what effect neuroprotective substances that promote the growth of the contact points and the docking possibilities of the neurotransmitters could have. The organoids are a good representation of the human brain, and with their help many things can be clarified in advance, before animal experiments and clinical studies become necessary. The current research thus represents an important step towards avoiding risks for humans in space exploration. The identification of the molecular causes of cognitive and neuropsychological deficits, their development and their progression also plays a decisive role for medicine on Earth.
Organiods
Scientists are focusing on cerebral organoids that are grown in vitro (“in glass”, outside the body) with the help of human stem cells, for example to study behavior in microgravity or the effects of radiation therapy on the brain. These organoids are not fully formed organs, but are similar in structure and function to the human brain and therefore enable a more precise investigation of tissue reactions. Scientists hope that this will lead to substantial progress in research and medical therapies, not least for neurological diseases.
Cellbox program
The Cellbox program was launched in 2011 by the German Space Agency at DLR. Cellbox missions enable investigations into the effects of space conditions on cells, tissues and organoids. The experiments originate from the research fields of gravitational biology, physiology, molecular biology and biomedicine. They each run for several weeks and are conducted in a low earth orbit. The experiments are carried out in miniature laboratories about the size of a smartphone – the Cellbox experiment chambers – which are exposed to microgravity and/or 1g-conditions on a centrifuge in an incubator for several days or weeks.
The Cellbox-4 and Cellbox-5 missions will orbit the Earth in a spacecraft for several weeks in 2026. Eight teams from German universities will carry out biological and biomedical experiments. The Cellbox missions are being carried out on behalf of the German Space Agency at DLR with funding from the Federal Ministry of Economics (BMWE).
Preparation of the HippoBox project
In the photo Carola Hartel from the Biophysics department at GSI/FAIR.
Credit
Photo: I. Schroeder, GSI/FAIR
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