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6 Min Read NASA’s PUNCH Mission to Revolutionize Our View of Solar Wind
Earth is immersed in material streaming from the Sun. This stream, called the solar wind, is washing over our planet, causing breathtaking auroras, impacting satellites and astronauts in space, and even affecting ground-based infrastructure.
NASA’s PUNCH (Polarimeter to Unify the Corona and Heliosphere) mission will be the first to image the Sun’s corona, or outer atmosphere, and solar wind together to better understand the Sun, solar wind, and Earth as a single connected system.
Launching no earlier than Feb. 28, 2025, aboard a SpaceX Falcon 9 rocket from Vandenberg Space Force Base in California, PUNCH will provide scientists with new information about how potentially disruptive solar events form and evolve. This could lead to more accurate predictions about the arrival of space weather events at Earth and impact on humanity’s robotic explorers in space.
“What we hope PUNCH will bring to humanity is the ability to really see, for the first time, where we live inside the solar wind itself,” said Craig DeForest, principal investigator for PUNCH at Southwest Research Institute’s Solar System Science and Exploration Division in Boulder, Colorado.
This video can be freely shared and downloaded at https://svs.gsfc.nasa.gov/14773.
Video credit: NASA’s Goddard Space Flight Center Seeing Solar Wind in 3D
The PUNCH mission’s four suitcase-sized satellites have overlapping fields of view that combine to cover a larger swath of sky than any previous mission focused on the corona and solar wind. The satellites will spread out in low Earth orbit to construct a global view of the solar corona and its transition to the solar wind. They will also track solar storms like coronal mass ejections (CMEs). Their Sun-synchronous orbit will enable them to see the Sun 24/7, with their view only occasionally blocked by Earth.
Typical camera images are two dimensional, compressing the 3D subject into a flat plane and losing information. But PUNCH takes advantage of a property of light called polarization to reconstruct its images in 3D. As the Sun’s light bounces off material in the corona and solar wind, it becomes polarized — meaning the light waves oscillate in a particular way that can be filtered, much like how polarized sunglasses filter out glare off of water or metal. Each PUNCH spacecraft is equipped with a polarimeter that uses three distinct polarizing filters to capture information about the direction that material is moving that would be lost in typical images.
“This new perspective will allow scientists to discern the exact trajectory and speed of coronal mass ejections as they move through the inner solar system,” said DeForest. “This improves on current instruments in two ways: with three-dimensional imaging that lets us locate and track CMEs which are coming directly toward us; and with a broad field of view, which lets us track those CMEs all the way from the Sun to Earth.”
All four spacecraft are synchronized to serve as a single “virtual instrument” that spans the whole PUNCH constellation.
Crews conduct additional solar array deployment testing for NASA’s PUNCH (Polarimeter to Unify the Corona and Heliosphere) satellites at Astrotech Space Operations located on Vandenberg Space Force Base in California on Wednesday, Jan. 22, 2025. USSF 30th Space Wing/Alex Valdez The PUNCH satellites include one Narrow Field Imager and three Wide Field Imagers. The Narrow Field Imager (NFI) is a coronagraph, which blocks out the bright light from the Sun to better see details in the Sun’s corona, recreating what viewers on Earth see during a total solar eclipse when the Moon blocks the face of the Sun — a narrower view that sees the solar wind closer to the Sun. The Wide Field Imagers (WFI) are heliospheric imagers that view the very faint, outermost portion of the solar corona and the solar wind itself — giving a wide view of the solar wind as it spreads out into the solar system.
“I’m most excited to see the ‘inbetweeny’ activity in the solar wind,” said Nicholeen Viall, PUNCH mission scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “This means not just the biggest structures, like CMEs, or the smallest interactions, but all the different types of solar wind structures that fill that in between area.”
When these solar wind structures from the Sun reach Earth’s magnetic field, they can drive dynamics that affect Earth’s radiation belts. To launch spacecraft through these belts, including ones that will carry astronauts to the Moon and beyond, scientists need to understand the solar wind structure and changes in this region.
Building Off Other Missions
“The PUNCH mission is built on the shoulders of giants,” said Madhulika Guhathakurta, PUNCH program scientist at NASA Headquarters in Washington. “For decades, heliophysics missions have provided us with glimpses of the Sun’s corona and the solar wind, each offering critical yet partial views of our dynamic star’s influence on the solar system.”
When scientists combine data from PUNCH and NASA’s Parker Solar Probe, which flies through the Sun’s corona, they will see both the big picture and the up-close details. Working together, Parker Solar Probe and PUNCH span a field of view from a little more than half a mile (1 kilometer) to over 160 million miles (about 260 million kilometers).
Additionally, the PUNCH team will combine their data with diverse observations from other missions, like NASA’s CODEX (Coronal Diagnostic Experiment) technology demonstration, which views the corona even closer to the surface of the Sun from its vantage point on the International Space Station. PUNCH’s data also complements observations from NASA’s EZIE (Electrojet Zeeman Imaging Explorer) — targeted for launch in March 2025 — which investigates the magnetic field perturbations associated with Earth’s high-altitude auroras that PUNCH will also spot in its wide-field view.
A conceptual animation showing the heliosphere, the vast bubble that is generated by the Sun’s magnetic field and envelops all the planets.
NASA’s Goddard Space Flight Center Conceptual Image Lab As the solar wind that PUNCH will observe travels away from the Sun and Earth, it will then be studied by the IMAP (Interstellar Mapping and Acceleration Probe) mission, which is targeting a launch in 2025.
“The PUNCH mission will bridge these perspectives, providing an unprecedented continuous view that connects the birthplace of the solar wind in the corona to its evolution across interplanetary space,” said Guhathakurta.
The PUNCH mission is scheduled to conduct science for at least two years, following a 90-day commissioning period after launch. The mission is launching as a rideshare with the agency’s next astrophysics observatory, SPHEREx (Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer).
“PUNCH is the latest heliophysics addition to the NASA fleet that delivers groundbreaking science every second of every day,” said Joe Westlake, heliophysics division director at NASA Headquarters in Washington. “Launching this mission as a rideshare bolsters its value to the nation by optimizing every pound of launch capacity to maximize the scientific return for the cost of a single launch.”
The PUNCH mission is led by Southwest Research Institute’s offices in San Antonio, Texas, and Boulder, Colorado. The mission is managed by the Explorers Program Office at NASA Goddard for NASA’s Science Mission Directorate in Washington.
By Abbey Interrante
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Header Image:
An artist’s concept showing the four PUNCH satellites orbiting Earth.
Credits: NASA’s Goddard Space Flight Center Conceptual Image Lab
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Last Updated Feb 21, 2025 Related Terms
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5 Min Read Webb Maps Full Picture of How Phoenix Galaxy Cluster Forms Stars
Spectroscopic data collected from NASA’s James Webb Space Telescope is overlayed on an image of the Phoenix cluster that combines data from NASA’s Hubble Space Telescope, Chandra X-ray Observatory and the Very Large Array (VLA) radio telescope. Credits:
NASA, CXC, NRAO, ESA, M. McDonald (MIT), M. Reefe (MIT), J. Olmsted (STScI) Discovery proves decades-old theory of galaxy feeding cycle.
Researchers using NASA’s James Webb Space Telescope have finally solved the mystery of how a massive galaxy cluster is forming stars at such a high rate. The confirmation from Webb builds on more than a decade of studies using NASA’s Chandra X-ray Observatory and Hubble Space Telescope, as well as several ground-based observatories.
The Phoenix cluster, a grouping of galaxies bound together by gravity 5.8 billion light-years from Earth, has been a target of interest for astronomers due to a few unique properties. In particular, ones that are surprising: a suspected extreme cooling of gas and a furious star formation rate despite a roughly 10 billion solar mass supermassive black hole at its core. In other observed galaxy clusters, the central supermassive black hole powers energetic particles and radiation that prevents gas from cooling enough to form stars. Researchers have been studying gas flows within this cluster to try to understand how it is driving such extreme star formation.
Image A: Phoenix Cluster (Hubble, Chandra, VLA Annotated)
Spectroscopic data collected from NASA’s James Webb Space Telescope is overlayed on an image of the Phoenix cluster that combines data from NASA’s Hubble Space Telescope, Chandra X-ray Observatory and the Very Large Array (VLA) radio telescope. Webb’s powerful sensitivity in the mid-infrared detected the cooling gas that leads to a furious rate of star formation in this massive galaxy cluster. Credit: NASA, CXC, NRAO, ESA, M. McDonald (MIT), M. Reefe (MIT), J. Olmsted (STScI) “We can compare our previous studies of the Phoenix cluster, which found differing cooling rates at different temperatures, to a ski slope,” said Michael McDonald of the Massachusetts Institute of Technology in Cambridge, principal investigator of the program. “The Phoenix cluster has the largest reservoir of hot, cooling gas of any galaxy cluster — analogous to having the busiest chair lift, bringing the most skiers to the top of the mountain. However, not all of those skiers were making it down the mountain, meaning not all the gas was cooling to low temperatures. If you had a ski slope where there were significantly more people getting off the ski lift at the top than were arriving at the bottom, that would be a problem!”
To date, in the Phoenix cluster, the numbers weren’t adding up, and researchers were missing a piece of the process. Webb has now found those proverbial skiers at the middle of the mountain, in that it has tracked and mapped the missing cooling gas that will ultimately feed star formation. Most importantly, this intermediary warm gas was found within cavities tracing the very hot gas, a searing 18 million degrees Fahrenheit, and the already cooled gas around 18,000 degrees Fahrenheit.
The team studied the cluster’s core in more detail than ever before with the Medium-Resolution Spectrometer on Webb’s Mid-Infrared Instrument (MIRI). This tool allows researchers to take two-dimenstional spectroscopic data from a region of the sky, during one set of observations.
“Previous studies only measured gas at the extreme cold and hot ends of the temperature distribution throughout the center of the cluster,” added McDonald. “We were limited — it was not possible to detect the ‘warm’ gas that we were looking for. With Webb, we could do this for the first time.”
Image B: Phoenix Cluster (Hubble, Chandra, VLA)
This image of the Phoenix cluster combines data from NASA’s Hubble Space Telescope, Chandra X-ray Observatory, and the Very Large Array radio telescope. X-rays from Chandra depict extremely hot gas in purple. Optical light data from Hubble show galaxies in yellow, and filaments of cooler gas where stars are forming in light blue. Outburst generated jets, represented in red, are seen in radio waves by the VLA radio telescope. NASA, CXC, NRAO, ESA, M. McDonald (MIT). A Quirk of Nature
Webb’s capability to detect this specific temperature of cooling gas, around 540,000 degrees Fahrenheit, is in part due to its instrumental capabilities. However, the researchers are getting a little help from nature, as well.
This oddity involves two very different ionized atoms, neon and oxygen, created in similar environments. At these temperatures, the emission from oxygen is 100 times brighter but is only visible in ultraviolet. Even though the neon is much fainter, it glows in the infrared, which allowed the researchers to take advantage of Webb’s advanced instruments.
“In the mid-infrared wavelengths detected by Webb, the neon VI signature was absolutely booming,” explained Michael Reefe, also of the Massachusetts Institute of Technology, lead author on the paper published in Nature. “Even though this emission is usually more difficult to detect, Webb’s sensitivity in the mid-infrared cuts through all of the noise.”
The team now hopes to employ this technique to study more typical galaxy clusters. While the Phoenix cluster is unique in many ways, this proof of concept is an important step towards learning about how other galaxy clusters form stars.The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
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Space Telescope Science Institute, Baltimore, Md.
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Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
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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 News Hubble News Hubble News Archive Social Media Media Resources Multimedia Multimedia Images Videos Sonifications Podcasts e-Books Online Activities Lithographs Fact Sheets Posters Hubble on the NASA App Glossary More 35th Anniversary Online Activities 5 Min Read Straight Shot: Hubble Investigates Galaxy with Nine Rings
LEDA 1313424, aptly nicknamed the Bullseye, is two and a half times the size of our Milky Way and has nine rings — six more than any other known galaxy. Credits:
NASA, ESA, Imad Pasha (Yale), Pieter van Dokkum (Yale) NASA’s Hubble Space Telescope has captured a cosmic bullseye! The gargantuan galaxy LEDA 1313424 is rippling with nine star-filled rings after an “arrow” — a far smaller blue dwarf galaxy — shot through its heart. Astronomers using Hubble identified eight visible rings, more than previously detected by any telescope in any galaxy, and confirmed a ninth using data from the W. M. Keck Observatory in Hawaii. Previous observations of other galaxies show a maximum of two or three rings.
“This was a serendipitous discovery,” said Imad Pasha, the lead researcher and a doctoral student at Yale University in New Haven, Connecticut. “I was looking at a ground-based imaging survey and when I saw a galaxy with several clear rings, I was immediately drawn to it. I had to stop to investigate it.” The team later nicknamed the galaxy the “Bullseye.”
LEDA 1313424, aptly nicknamed the Bullseye, is two and a half times the size of our Milky Way and has nine rings — six more than any other known galaxy. High-resolution imagery from NASA’s Hubble Space Telescope confirmed eight rings, and data from the W. M. Keck Observatory in Hawaii confirmed a ninth. Hubble and Keck also confirmed which galaxy dove through the Bullseye, creating these rings: the blue dwarf galaxy that sits to its immediate center-left. NASA, ESA, Imad Pasha (Yale), Pieter van Dokkum (Yale)
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Hubble and Keck’s follow-up observations also helped the researchers prove which galaxy plunged through the center of the Bullseye — a blue dwarf galaxy to its center-left. This relatively tiny interloper traveled like a dart through the core of the Bullseye about 50 million years ago, leaving rings in its wake like ripples in a pond. A thin trail of gas now links the pair, though they are currently separated by 130,000 light-years.
“We’re catching the Bullseye at a very special moment in time,” said Pieter G. van Dokkum, a co-author of the new study and a professor at Yale. “There’s a very narrow window after the impact when a galaxy like this would have so many rings.”
Galaxies collide or barely miss one another quite frequently on cosmic timescales, but it is extremely rare for one galaxy to dive through the center of another. The blue dwarf galaxy’s straight trajectory through the Bullseye later caused material to move both inward and outward in waves, setting off new regions of star formation.
How big is the Bullseye? Our Milky Way galaxy is about 100,000 light-years in diameter, and the Bullseye is almost two-and-a-half times larger, at 250,000 light-years across.
This illustration compares the size of our own Milky Way galaxy to gargantuan galaxy LEDA 1313424, nicknamed the Bullseye. The Milky Way is about 100,000 light-years in diameter, and the Bullseye is almost two-and-a-half times larger, at 250,000 light-years across. NASA, ESA, Ralf Crawford (STScI)
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The researchers used Hubble’s crisp vision to carefully to pinpoint the location of most of its rings, since many are piled up at the center. “This would have been impossible without Hubble,” Pasha said.
They used Keck to confirm one more ring. The team suspects a 10th ring also existed, but has faded and is no longer detectable. They estimate it might lie three times farther out than the widest ring in Hubble’s image.
A One-to-One Match with Predictions
Pasha also found a stunning connection between the Bullseye and a long-established theory: The galaxy’s rings appear to have moved outward almost exactly as predicted by models.
“That theory was developed for the day that someone saw so many rings,” van Dokkum said. “It is immensely gratifying to confirm this long-standing prediction with the Bullseye galaxy.”
If viewed from above, it would be more obvious that the galaxy’s rings aren’t evenly spaced like those on a dart board. Hubble’s image shows the galaxy from a slight angle. “If we were to look down at the galaxy directly, the rings would look circular, with rings bunched up at the center and gradually becoming more spaced out the farther out they are,” Pasha explained.
To visualize how these rings may have formed, think about dropping a pebble into a pond. The first ring ripples out, becoming the widest over time, while others continue to form after it.
The researchers suspect that the first two rings in the Bullseye formed quickly and spread out in wider circles. The formation of additional rings may have been slightly staggered, since the blue dwarf galaxy’s flythrough affected the first rings more significantly.
This illustration shows the massive galaxy nicknamed the Bullseye face-on. Dotted circles indicate where each of its rings are, which formed like ripples in a pond after a blue dwarf galaxy (not shown) shot through its core about 50 million years ago. NASA’s Hubble Space Telescope helped researchers carefully pinpoint the location of most of its rings, many of which are piled up at the center. Data from the W. M. Keck Observatory in Hawaii helped the team confirm another ring. NASA, ESA, Ralf Crawford (STScI)
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Individual stars’ orbits were largely undisturbed, though groups of stars did “pile up” to form distinguishable rings over millions of years. The gas, however, was carried outward, and mixed with dust to form new stars, further brightening the Bullseye’s rings.
There’s a lot more research to be done to figure out which stars existed before and after the blue dwarf’s “fly through.” Astronomers will now also be able to improve models showing how the galaxy may continue to evolve over billions of years, including the disappearance of additional rings.
Although this discovery was a chance finding, astronomers can look forward to finding more galaxies like this one soon. “Once NASA’s Nancy Grace Roman Space Telescope begins science operations, interesting objects will pop out much more easily,” van Dokkum explained. “We will learn how rare these spectacular events really are.”
The team’s paper was published on the February 4, 2025 in The Astrophysical Journal Letters.
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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Hubble Space Telescope 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 News Hubble News Hubble News Archive Social Media Media Resources Multimedia Multimedia Images Videos Sonifications Podcasts e-Books Online Activities Lithographs Fact Sheets Glossary Posters Hubble on the NASA App More 35th Anniversary 6 Min Read NASA’s Hubble Traces Hidden History of Andromeda Galaxy
This photomosaic of the Andromeda galaxy is the largest ever assembled from Hubble observations. Credits:
NASA, ESA, Benjamin F. Williams (UWashington), Zhuo Chen (UWashington), L. Clifton Johnson (Northwestern); Image Processing: Joseph DePasquale (STScI) In the years following the launch of NASA’s Hubble Space Telescope, astronomers have tallied over 1 trillion galaxies in the universe. But only one galaxy stands out as the most important nearby stellar island to our Milky Way — the magnificent Andromeda galaxy (Messier 31). It can be seen with the naked eye on a very clear autumn night as a faint cigar-shaped object roughly the apparent angular diameter of our Moon.
A century ago, Edwin Hubble first established that this so-called “spiral nebula” was actually very far outside our own Milky Way galaxy — at a distance of approximately 2.5 million light-years or roughly 25 Milky Way diameters. Prior to that, astronomers had long thought that the Milky way encompassed the entire universe. Overnight, Hubble’s discovery turned cosmology upside down by unveiling an infinitely grander universe.
Now, a century later, the space telescope named for Hubble has accomplished the most comprehensive survey of this enticing empire of stars. The Hubble telescope is yielding new clues to the evolutionary history of Andromeda, and it looks markedly different from the Milky Way’s history.
This is largest photomosaic ever assembled from Hubble Space Telescope observations. It is a panoramic view of the neighboring Andromeda galaxy, located 2.5 million light-years away. It took over 10 years to make this vast and colorful portrait of the galaxy, requiring over 600 Hubble overlapping snapshots that were challenging to stitch together. The galaxy is so close to us, that in angular size it is six times the apparent diameter of the full Moon, and can be seen with the unaided eye. For Hubble’s pinpoint view, that’s a lot of celestial real estate to cover. This stunning, colorful mosaic captures the glow of 200 million stars. That’s still a fraction of Andromeda’s population. And the stars are spread across about 2.5 billion pixels. The detailed look at the resolved stars will help astronomers piece together the galaxy’s past history that includes mergers with smaller satellite galaxies. NASA, ESA, Benjamin F. Williams (UWashington), Zhuo Chen (UWashington), L. Clifton Johnson (Northwestern); Image Processing: Joseph DePasquale (STScI)
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Without Andromeda as a proxy for spiral galaxies in the universe at large, astronomers would know much less about the structure and evolution of our own Milky Way. That’s because we are embedded inside the Milky Way. This is like trying to understand the layout of New York City by standing in the middle of Central Park.
“With Hubble we can get into enormous detail about what’s happening on a holistic scale across the entire disk of the galaxy. You can’t do that with any other large galaxy,” said principal investigator Ben Williams of the University of Washington. Hubble’s sharp imaging capabilities can resolve more than 200 million stars in the Andromeda galaxy, detecting only stars brighter than our Sun. They look like grains of sand across the beach. But that’s just the tip of the iceberg. Andromeda’s total population is estimated to be 1 trillion stars, with many less massive stars falling below Hubble’s sensitivity limit.
Photographing Andromeda was a herculean task because the galaxy is a much bigger target on the sky than the galaxies Hubble routinely observes, which are often billions of light-years away. The full mosaic was carried out under two Hubble programs. In total, it required over 1,000 Hubble orbits, spanning more than a decade.
This panorama started with the Panchromatic Hubble Andromeda Treasury (PHAT) program about a decade ago. Images were obtained at near-ultraviolet, visible, and near-infrared wavelengths using the Advanced Camera for Surveys and the Wide Field Camera 3 aboard Hubble to photograph the northern half of Andromeda.
This is the largest photomosaic ever made by the Hubble Space Telescope. The target is the vast Andromeda galaxy that is only 2.5 million light-years from Earth, making it the nearest galaxy to our own Milky Way. Andromeda is seen almost edge-on, tilted by 77 degrees relative to Earth’s view. The galaxy is so large that the mosaic is assembled from approximately 600 separate overlapping fields of view taken over 10 years of Hubble observing — a challenge to stitch together over such a large area. The mosaic image is made up of at least 2.5 billion pixels. Hubble resolves an estimated 200 million stars that are hotter than our Sun, but still a fraction of the galaxy’s total estimated stellar population. Interesting regions include: (a) Clusters of bright blue stars embedded within the galaxy, background galaxies seen much farther away, and photo-bombing by a couple bright foreground stars that are actually inside our Milky Way; (b) NGC 206 the most conspicuous star cloud in Andromeda; (c) A young cluster of blue newborn stars; (d) The satellite galaxy M32, that may be the residual core of a galaxy that once collided with Andromeda; (e) Dark dust lanes across myriad stars.
NASA, ESA, Benjamin F. Williams (UWashington), Zhuo Chen (UWashington), L. Clifton Johnson (Northwestern); Image Processing: Joseph DePasquale (STScI)
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This program was followed up by the Panchromatic Hubble Andromeda Southern Treasury (PHAST), recently published in The Astrophysical Journal and led by Zhuo Chen at the University of Washington, which added images of approximately 100 million stars in the southern half of Andromeda. This region is structurally unique and more sensitive to the galaxy’s merger history than the northern disk mapped by the PHAT survey.
The combined programs collectively cover the entire disk of Andromeda, which is seen almost edge-on — tilted by 77 degrees relative to Earth’s view. The galaxy is so large that the mosaic is assembled from approximately 600 separate fields of view. The mosaic image is made up of at least 2.5 billion pixels.
The complementary Hubble survey programs provide information about the age, heavy-element abundance, and stellar masses inside Andromeda. This will allow astronomers to distinguish between competing scenarios where Andromeda merged with one or more galaxies. Hubble’s detailed measurements constrain models of Andromeda’s merger history and disk evolution.
A Galactic ‘Train Wreck’
Though the Milky Way and Andromeda formed presumably around the same time many billions of years ago, observational evidence shows that they have very different evolutionary histories, despite growing up in the same cosmological neighborhood. Andromeda seems to be more highly populated with younger stars and unusual features like coherent streams of stars, say researchers. This implies it has a more active recent star-formation and interaction history than the Milky Way.
“Andromeda’s a train wreck. It looks like it has been through some kind of event that caused it to form a lot of stars and then just shut down,” said Daniel Weisz at the University of California, Berkeley. “This was probably due to a collision with another galaxy in the neighborhood.”
A possible culprit is the compact satellite galaxy Messier 32, which resembles the stripped-down core of a once-spiral galaxy that may have interacted with Andromeda in the past. Computer simulations suggest that when a close encounter with another galaxy uses up all the available interstellar gas, star formation subsides.
The Andromeda Galaxy, our closest galactic neighbor, holds over 1 trillion stars and has been a key to unlocking the secrets of the universe. Thanks to NASA’s Hubble Space Telescope, we’re now seeing Andromeda in stunning new detail, revealing its dynamic history and unique structure.
Credit: NASA’s Goddard Space Flight Center; Lead Producer: Paul Morris
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“Andromeda looks like a transitional type of galaxy that’s between a star-forming spiral and a sort of elliptical galaxy dominated by aging red stars,” said Weisz. “We can tell it’s got this big central bulge of older stars and a star-forming disk that’s not as active as you might expect given the galaxy’s mass.”
“This detailed look at the resolved stars will help us to piece together the galaxy’s past merger and interaction history,” added Williams.
Hubble’s new findings will support future observations by NASA’s James Webb Space Telescope and the upcoming Nancy Grace Roman Space Telescope. Essentially a wide-angle version of Hubble (with the same sized mirror), Roman will capture the equivalent of at least 100 high-resolution Hubble images in a single exposure. These observations will complement and extend Hubble’s huge dataset.
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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Claire Andreoli (claire.andreoli@nasa.gov)
NASA’s Goddard Space Flight Center, Greenbelt, MD
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Space Telescope Science Institute, Baltimore, MD
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Last Updated Jan 16, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
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