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Jupiter's Comet Collision Sites As Seen in Visible and Ultraviolet Light
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By NASA
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
The Jet Propulsion Laboratory perfected aerogel for the Stardust mission. Under Stardust, bricks of aerogel covered panels on a spacecraft that flew behind a comet, with the microporous material “soft catching” any particles that might strike it and preserving them for return to Earth.NASA Consisting of 99% air, aerogel is the world’s lightest solid. This unique material has found purpose in several forms — from NASA missions to high fashion.
Driven by the desire to create a 3D cloud, Greek artist, Ioannis Michaloudis, learned to use aerogel as an artistic medium. His journey spanning more than 25 years took him to the Massachusetts Institute of Technology (MIT) in Cambridge; Shivaji University in Maharashtra, India, and NASA’s Jet Propulsion Laboratory in Southern California.
A researcher at MIT introduced Michaloudis to aerogel after hearing of his cloud-making ambition, and he was immediately intrigued. Aerogel is made by combining a polymer with a solvent to create a gel and flash-drying it under pressure, leaving a solid filled with microscopic pores.
Scientists at JPL chose aerogel in the mid-1990s to enable the Stardust mission, with the idea that a porous surface could capture particles while flying on a probe behind a comet. Aerogel worked in lab tests, but it was difficult to manufacture consistently and needed to be made space-worthy. NASA JPL hired materials scientist Steve Jones to develop a flight-ready aerogel, and he eventually got funding for an aerogel lab.
The aerogel AirSwipe bag Michaloudis created for Coperni’s 2024 fall collection debut appears almost luminous in its model’s hand. The bag immediately captured the world’s attention.Coperni
The Stardust mission succeeded, and when Michaloudis heard of it, he reached out to JPL, where Jones invited him to the lab. Now retired, Jones recalled, “I went through the primer on aerogel with him, the different kinds you could make and their different properties.” The size of Jones’ reactor, enabling it to make large objects, impressed Michaloudis. With tips on how to safely operate a large reactor, he outfitted his own lab with one.
In India, Michaloudis learned recipes for aerogels that can be molded into large objects and don’t crack or shrink during drying. His continued work with aerogels has created an extensive art portfolio.
Michaloudis has had more than a dozen solo exhibitions. All his artwork involves aerogel, drawing attention with its unusual qualities. An ethereal, translucent blue, it casts an orange shadow and can withstand molten metals.
In 2020, Michaloudis created a quartz-encapsulated aerogel pendant for the centerpiece of that year’s collection from French jewelry house Boucheron. Michaloudis also captured the fashion and design world’s attention with a handbag made of aerogel, unveiled at Coperni’s 2024 fall collection debut.
NASA was a crucial step along the way. “I am what I am, and we made what we made thanks to the Stardust project,” said Michaloudis.
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Last Updated Jun 09, 2025 Related Terms
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By NASA
Explore Hubble Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts Multimedia Images Videos Sonifications Podcasts e-Books Online Activities 3D Hubble Models Lithographs Fact Sheets Posters Hubble on the NASA App Glossary News Hubble News Social Media Media Resources More 35th Anniversary Online Activities 5 Min Read Apocalypse When? Hubble Casts Doubt on Certainty of Galactic Collision
This NASA Hubble Space Telescope image of NGC 520 offers one example of possible encounter scenarios between our Milky Way and the Andromeda galaxy. NGC 520 is the product of a collision between two disk galaxies that started 300 million years ago. Credits:
NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and B. Whitmore (STScI) As far back as 1912, astronomers realized that the Andromeda galaxy — then thought to be only a nebula — was headed our way. A century later, astronomers using NASA’s Hubble Space Telescope were able to measure the sideways motion of Andromeda and found it was so negligible that an eventual head-on collision with the Milky Way seemed almost certain.
A smashup between our own galaxy and Andromeda would trigger a firestorm of star birth, supernovae, and maybe toss our Sun into a different orbit. Simulations had suggested it was as inevitable as, in the words of Benjamin Franklin, “death and taxes.”
But now a new study using data from Hubble and the European Space Agency’s (ESA) Gaia space telescope says “not so fast.” Researchers combining observations from the two space observatories re-examined the long-held prediction of a Milky Way – Andromeda collision, and found it is far less inevitable than astronomers had previously suspected.
“We have the most comprehensive study of this problem today that actually folds in all the observational uncertainties,” said Till Sawala, astronomer at the University of Helsinki in Finland and lead author of the study, which appears today in the journal Nature Astronomy.
His team includes researchers at Durham University, United Kingdom; the University of Toulouse, France; and the University of Western Australia. They found that there is approximately a 50-50 chance of the two galaxies colliding within the next 10 billion years. They based this conclusion on computer simulations using the latest observational data.
These galaxy images illustrate three possible encounter scenarios between our Milky Way and the neighboring Andromeda galaxy. Top left: Galaxies M81 and M82. Top right: NGC 6786, a pair of interacting galaxies. Bottom: NGC 520, two merging galaxies. Science: NASA, ESA, STScI, DSS, Till Sawala (University of Helsinki); Image Processing: Joseph DePasquale (STScI) Sawala emphasized that predicting the long-term future of galaxy interactions is highly uncertain, but the new findings challenge the previous consensus and suggest the fate of the Milky Way remains an open question.
“Even using the latest and most precise observational data available, the future of the Local Group of several dozen galaxies is uncertain. Intriguingly, we find an almost equal probability for the widely publicized merger scenario, or, conversely, an alternative one where the Milky Way and Andromeda survive unscathed,” said Sawala.
The collision of the two galaxies had seemed much more likely in 2012, when astronomers Roeland van der Marel and Tony Sohn of the Space Telescope Science Institute in Baltimore, Maryland published a detailed analysis of Hubble observations over a five-to-seven-year period, indicating a direct impact in no more than 5 billion years.
“It’s somewhat ironic that, despite the addition of more precise Hubble data taken in recent years, we are now less certain about the outcome of a potential collision. That’s because of the more complex analysis and because we consider a more complete system. But the only way to get to a new prediction about the eventual fate of the Milky Way will be with even better data,” said Sawala.
100,000 Crash-Dummy Simulations
Astronomers considered 22 different variables that could affect the potential collision between our galaxy and our neighbor, and ran 100,000 simulations called Monte Carlo simulations stretching to 10 billion years into the future.
“Because there are so many variables that each have their errors, that accumulates to rather large uncertainty about the outcome, leading to the conclusion that the chance of a direct collision is only 50% within the next 10 billion years,” said Sawala.
“The Milky Way and Andromeda alone would remain in the same plane as they orbit each other, but this doesn’t mean they need to crash. They could still go past each other,” said Sawala.
Researchers also considered the effects of the orbits of Andromeda’s large satellite galaxy, M33, and a satellite galaxy of the Milky Way called the Large Magellanic Cloud (LMC).
“The extra mass of Andromeda’s satellite galaxy M33 pulls the Milky Way a little bit more towards it. However, we also show that the LMC pulls the Milky Way off the orbital plane and away from Andromeda. It doesn’t mean that the LMC will save us from that merger, but it makes it a bit less likely,” said Sawala.
In about half of the simulations, the two main galaxies fly past each other separated by around half a million light-years or less (five times the Milky Way’s diameter). They move outward but then come back and eventually merge in the far future. The gradual decay of the orbit is caused by a process called dynamical friction between the vast dark-matter halos that surround each galaxy at the beginning.
In most of the other cases, the galaxies don’t even come close enough for dynamical friction to work effectively. In this case, the two galaxies can continue their orbital waltz for a very long time.
The new result also still leaves a small chance of around 2% for a head-on collision between the galaxies in only 4 to 5 billion years. Considering that the warming Sun makes Earth uninhabitable in roughly 1 billion years, and the Sun itself will likely burn out in 5 billion years, a collision with Andromeda is the least of our cosmic worries.
The Hubble Space Telescope has been operating for over 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.
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Milky Way and Andromeda Encounters
This selection of images of external galaxies illustrates three encounter scenarios between our Milky Way and the neighboring Andromeda galaxy. Top left: Galaxies M81 and M82. Top right: NGC 6786, a pair of interacting galaxies. Bottom: NGC 520, two merging galaxies.
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Last Updated Jun 02, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center
Contact Media Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov
Ray Villard
Space Telescope Science Institute
Baltimore, Maryland
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By USH
On the night of Friday, May 16, something extraordinary lit up the skies over the American Southwest. A brilliant, fast-moving streak of light that captivated onlookers from Arizona to Colorado.
Witnesses in towns such as Safford, Fountain Hills, and Payson, as well as regions of New Mexico and Colorado, were left asking the same question: What exactly did we just see?
Speculation spread rapidly. Some suggested a Chinese rocket launch earlier that day could be responsible, possibly placing satellites into orbit. Others floated more exotic theories: perhaps STEVE, a rare atmospheric light phenomenon similar to the aurora borealis, or even a “light pillar,” formed when light reflects off high-altitude ice crystals.
Attempts to reach officials at Luke Air Force Base near Phoenix, Davis-Monthan Air Force Base in southern Arizona, and Kirtland Air Force Base in Albuquerque have so far yielded no response.
What if it wasn’t a rocket plume from a Chinese launch at all? What if something entirely different passed near our planet, like a comet or UFO, or perhaps it was a test of a space-based weapon or a directed-energy system?
Whatever it may have been, it remains a strange phenomenon, leaving many to wonder what truly streaked across the sky.
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By NASA
6 min read
NASA Observes First Visible-light Auroras at Mars
On March 15, 2024, near the peak of the current solar cycle, the Sun produced a solar flare and an accompanying coronal mass ejection (CME), a massive explosion of gas and magnetic energy that carries with it large amounts of solar energetic particles. This solar activity led to stunning auroras across the solar system, including at Mars, where NASA’s Perseverance Mars rover made history by detecting them for the first time from the surface of another planet.
The first visible-light image of green aurora on Mars (left), taken by the Mastcam-Z instrument on NASA’s Perseverance Mars rover. On the right is a comparison image of the night sky of Mars without aurora but featuring the Martian moon Deimos. The moonlit Martian night sky, lit up mostly by Mars’ nearer and larger moon Phobos (outside the frame) has a reddish-brown hue due to the dust in the atmosphere, so when green auroral light is added, the sky takes on a green-yellow tone, as seen in the left image. NASA/JPL-Caltech/ASU/MSSS/SSI “This exciting discovery opens up new possibilities for auroral research and confirms that auroras could be visible to future astronauts on Mars’ surface.” said Elise Knutsen, a postdoctoral researcher at the University of Oslo in Norway and lead author of the Science Advances study, which reported the detection.
Picking the right aurora
On Earth, auroras form when solar particles interact with the global magnetic field, funneling them to the poles where they collide with atmospheric gases and emit light. The most common color, green, is caused by excited oxygen atoms emitting light at a wavelength of 557.7 nanometers. For years, scientists have theorized that green light auroras could also exist on Mars but suggested they would be much fainter and harder to capture than the green auroras we see on Earth.
Due to the Red Planet’s lack of a global magnetic field, Mars has different types of auroras than those we have on Earth. One of these is solar energetic particle (SEP) auroras, which NASA’s MAVEN (Mars Atmosphere and Volatile EvolutioN) mission discovered in 2014. These occur when super-energetic particles from the Sun hit the Martian atmosphere, causing a reaction that makes the atmosphere glow across the whole night sky.
While MAVEN had observed SEP auroras in ultraviolet light from orbit, this phenomenon had never been observed in visible light from the ground. Since SEPs typically occur during solar storms, which increase during solar maximum, Knutsen and her team set their sights on capturing visible images and spectra of SEP aurora from Mars’ surface at the peak of the Sun’s current solar cycle.
Coordinating the picture-perfect moment
Through modeling, Knutsen and her team determined the optimal angle for the Perseverance rover’s SuperCam spectrometer and Mastcam-Z camera to successfully observe the SEP aurora in visible light. With this observation strategy in place, it all came down to the timing and understanding of CMEs.
“The trick was to pick a good CME, one that would accelerate and inject many charged particles into Mars’ atmosphere,” said Knutsen.
That is where the teams at NASA’s Moon to Mars (M2M) Space Weather Analysis Office and the Community Coordinated Modeling Center (CCMC), both located at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, came in. The M2M team provides real-time analysis of solar eruptions to the CCMC for initiating simulations of CMEs to determine if they might impact current NASA missions. When the simulations suggest potential impacts, the team sends out an alert.
At the University of California, Berkeley, space physicist Christina Lee received an alert from the M2M office about the March 15, 2024, CME. Lee, a member of the MAVEN mission team who serves as the space weather lead, determined there was a notable solar storm heading toward the Red Planet,which could arrive in a few days. She immediately issued the Mars Space Weather Alert Notification to currently operating Mars missions.
“This allows the science teams of Perseverance and MAVEN to anticipate impacts of interplanetary CMEs and the associated SEPs,” said Lee.
“When we saw the strength of this one,” Knutsen said, “we estimated it could trigger aurora bright enough for our instruments to detect.”
A few days later, the CME impacted Mars, providing a lightshow for the rover to capture, showing the aurora to be nearly uniform across the sky at an emission wavelength of exactly 557.7 nm. To confirm the presence of SEPs during the aurora observation, the team looked to MAVEN’s SEP instrument, which was additionally corroborated by data from ESA’s (European Space Agency) Mars Express mission. Data from both missions confirmed that the rover team had managed to successfully catch a glimpse of the phenomenon in the very narrow time window available.
“This was a fantastic example of cross-mission coordination. We all worked together quickly to facilitate this observation and are thrilled to have finally gotten a sneak peek of what astronauts will be able to see there some day,” said Shannon Curry, MAVEN principal investigator and research scientist at the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder (CU Boulder).
The future of aurora on Mars
By coordinating the Perseverance observations with measurements from MAVEN’s SEP instrument, the teams could help each other determine that the observed 557.7 nm emission came from solar energetic particles. Since this is the same emission line as the green aurora on Earth, it is likely that future Martian astronauts would be able to see this type of aurora.
“Perseverance’s observations of the visible-light aurora confirm a new way to study these phenomena that’s complementary to what we can observe with our Mars orbiters,” said Katie Stack Morgan, acting project scientist for Perseverance at NASA’s Jet Propulsion Laboratory in Southern California. “A better understanding of auroras and the conditions around Mars that lead to their formation are especially important as we prepare to send human explorers there safely.”
On September 21, 2014, NASA’s MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft entered orbit around Mars. The mission has produced a wealth of data about how Mars’ atmosphere responds to the Sun and solar wind NASA/JPL-Caltech More About Perseverance and MAVEN
The Mars 2020 Perseverance mission is part of NASA’s Mars Exploration Program portfolio and NASA’s Moon to Mars exploration approach, which includes Artemis missions to the Moon that will help prepare for human exploration of the Red Planet. NASA’s Jet Propulsion Laboratory, which is managed for the agency by Caltech, built and manages operations of the Perseverance rover.
The MAVEN mission, also part of NASA’s Mars Exploration Program portfolio, is led by LASP at CU Boulder. It’s managed by NASA’s Goddard Space Flight Center and was built and operated by Lockheed Martin Space, with navigation and network support from NASA’s JPL.
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By Willow Reed
Laboratory for Atmospheric and Space Physics (LASP), University of Colorado Boulder
Media Contact:
Karen Fox / Molly Wasser
Headquarters, Washington
202-358-1600
karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov
Nancy N. Jones
NASA’s Goddard Space Flight Center, Greenbelt, Md.
DC Agle
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-9011
agle@jpl.nasa.gov
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Last Updated May 14, 2025 Related Terms
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