Andromeda is the only major galaxy in the universe that is speeding closer to the Milky Way as all the others rush away. Now, a new analysis of Hubble Space Telescope data hints that our galactic next-door neighbor may be winding down from a big burst of activity as it draws toward a possible collision with our galaxy.

The new study found that the Andromeda galaxy (M31) has been steadily slowing its production of new stars over the past 500 million years. The findings suggest that the galaxy is naturally winding down after a more active period, offering astronomers valuable clues about how large spiral galaxies evolve.

Andromeda is a giant spiral galaxy similar to the Milky Way, but with around twice its mass. As the nearest large spiral galaxy to Earth, it provides an ideal laboratory for studying galaxy formation and evolution. An understanding of when and where stars form is essential for explaining how galaxies develop and change over time.

The new research, published July 27 in The Astrophysical Journal, combines two major Hubble surveys that mapped roughly two-thirds of Andromeda's disk, including around 200 million stars. It's already known that Andromeda experienced a dramatic burst of star formation about 2 billion years ago, which is thought to have formed about a fifth of all the stars in the galaxy. That starburst is thought to be the result of a merger with another galaxy, probably the compact elliptical galaxy M32, which now orbits Andromeda.

The new study found that Andromeda formed stars at a rate of around one solar mass per year 500 million years ago. By 40 million years ago, that rate had halved, while today the rate has fallen to just one-fifth of a solar mass each year. Researchers found that most recent star formation in Andromeda has been concentrated within a ring about 32,000 light-years from the galaxy's center and that the decreasing activity within this region is largely responsible for the overall decline. That suggests the galaxy is gradually winding down from its previous burst of star formation rather than suddenly running out of material.

Scientists also investigated whether M32 may have contributed to the slowdown. Regions closest to M32 show a more recent decline in star formation, making the companion galaxy a possible influence, although the evidence remains inconclusive.

"We need to measure the individual stars because they are the fossil record of the galaxy's formation," study co-author Ben Williams, an astronomer at the University of Washington, said in a NASA statement. "Hubble is the only telescope that can give you high enough spatial resolution over a large enough area to be able to do that in Andromeda."Although the team will continue studying Hubble's archive, they will also target observations from NASA's Nancy Grace Roman Space Telescope, which will launch on a SpaceX Falcon Heavy rocket as soon as Aug. 30. With a field of view at least 100 times larger than Hubble's, Roman will survey the entire Andromeda galaxy and its surrounding halo in unprecedented detail.

Andromeda is best observed in November and is visible to the naked eye, even from locations with moderate light pollution. The galaxy may collide with the Milky Way about 5 billion years from now, though its ultimate trajectory is still uncertain.

For the first time ever, an astronomer has witnessed a comet changing the speed and direction of its own spin, thanks to newly analyzed Hubble Space Telescope photos. The unexpected reversal was triggered by "outgassing" jets that shot an icy mix of gas and dust into the solar system, according to a new study.

The comet, dubbed 41P Tuttle-Giacobini-Kresák (41P for short), was discovered by American astronomer Horace Parnell Tuttle in 1858, before being rediscovered by French astronomer Michel Giacobini in 1907 and again by Slovak scientist L'ubor Kresák in 1951 (hence its lengthy name). Comet 41P likely originates from the Kuiper Belt — the ring of asteroids, comets and dwarf planets beyond the orbit of Neptune — and likely spent the majority of its long life circling the sun on a timescale of decades to centuries.

But around 1,500 years ago, 41P was tugged off its usual course by a close interaction with Jupiter. Now, it is locked in a much tighter orbit, circling our home star every 5.4 years. As the comet reaches its closest point to the sun, known as perihelion, it also passes by Earth and becomes clearly visible with a telescope. Its last flyby of the sun occurred in 2022, but it was also studied extensively in 2001, 2006, 2011 and 2017.

During the 2017 flyby, astronomers noticed that 41P's rate of rotation slowed significantly as the comet shot past Earth ‪—‬ which scientists had previously attributed to a standard outgassing event. Hubble also captured extensive photos of the flyby. However, these images were filed away and had not been studied properly.

Now, in the new study published March 26 in The Astronomical Journal, an astronomer has analyzed the Hubble images from 2017 and discovered that the sudden slowdown was followed by a previously unrecognized acceleration event.

By comparing the Hubble images to data collected by ground-based telescopes, study author David Jewitt, an astronomer at UCLA, estimated the changes in 41P's rotation throughout 2017. He found that by May of that year, the comet's spin had slowed to around one rotation every 46 to 60 hours, which was around three times slower than it was spinning in March 2017. But by December 2017, the comet was completing a rotation once every 14 hours, which was a much quicker return to form than previously realized, according to Live Science's sister site Space.com.

But if outgassing had slowed the comet's spin, how could it speed it up again so quickly? The only thing that makes sense, Jewitt argues, is if the direction of the comet's spin was completely reversed.

"It's like pushing a merry-go-round," he said in a statement. "If it's turning in one direction, and then you push against that, you can slow it and reverse it."

With the Hubble data, Jewitt also constrained the true size of 41P's nucleus, which is approximately 0.6 miles (1 kilometer) across — around three times wider than Paris' Eiffel Tower is tall. That might sound impressive, but it is actually quite small for a comet. And its diminutive size may prove key in explaining its unusual behavior.

Passing gas

Almost all known comets have been observed "outgassing" at some point in their lifetimes. This phenomenon occurs when ice, gas and dust from the comet's interior shoots out of small cracks that appear in its nucleus — normally due to an increased proximity to the sun, which allows solar radiation to sublimate the comet's innards and crack its icy shell.

In recent years, we have seen several stunning examples of outgassing in action, including the demonic horns of the explosive "devil comet" 12P/Pons-Brooks, which slingshotted around the sun in 2024, and the multiple jets and "anti-tail" of the interstellar object 3I/ATLAS, which was spotted shooting through the solar system last year.

Scientists previously knew that outgassing could alter the spin of a comet, but most of these objects are too large for an outflowing jet to make much of a difference before it fades away. However, 41P's relatively small size likely enabled the comet's jets to make a greater impact.

"Jets of gas streaming off the surface can act like small thrusters," Jewitt said in the statement. "If those jets are unevenly distributed, they can dramatically change how a comet, especially a small one, rotates."

Experts are unsure if 41P's extreme outgassing event was caused by multiple jets or a single massive outflow. But if repeated events occur over the comet's next few perihelia, the icy ball could end up ripping itself apart, similar to Comet C/2025 K1 (ATLAS), which spectacularly broke apart in late 2025.

"I expect this nucleus [41P] will very quickly self-destruct," Jewitt said.

Saturn may be famous for its rings, but it has long fascinated scientists for another reason: its restless atmosphere, which is shaped by fierce winds, stubborn megastorms and strange weather patterns that can linger for years.

Now, two new views from the James Webb and Hubble space telescopes are cutting through the ringed planet's clouds, giving researchers what NASA calls the "most comprehensive view of Saturn to date." Together, the images let researchers "slice" through Saturn's atmosphere at different heights.

The paired observations capture one of Saturn's strangest landmarks: the famous hexagon at the north pole. According to NASA, the faint edges of the six-sided jet stream appear in both images. These pictures could be some of the last high-resolution views of the hexagon until the 2040s, as Saturn's north pole is about to tip into 15 years of winter darkness.

Studying Saturn's atmosphere not only allows scientists to understand how large, planet-size storms grow and thrive but also gives further insight into how the planet formed and evolved over billions of years.

A planet seen two ways

In August 2024, Hubble took its visible-light image of Saturn as part of the Outer Planet Atmospheres Legacy program, a decade-long project that tracks the outer planets annually. The James Webb Space Telescope (JWST) captured its infrared image a few months later, in November 2024. Those observations, taken 14 weeks apart, showed the ringed planet shifting from northern summer toward its 2025 equinox.

The two telescopes saw very different Saturns.

While Hubble captured Saturn's pale-yellow bands and brilliant-white rings, JWST's infrared image revealed even more striking details. In the infrared view, Saturn's rings transformed into glowing blue "because they are made of highly reflective water ice," NASA representatives said in a statement. Saturn's poles also shone a strange gray-green, emitting light at wavelengths of about 4.3 microns. These emissions could be from either light scattering off of high-altitude aerosols or auroras, NASA suggested. (The telescope recently caught giant auroras shining on Uranus.)

As Saturn tilts into its southern springtime, both space telescopes will continue to keep their eyes on its atmosphere, perhaps revealing more about the planet's weather dynamics. Until then, Saturn is keeping some of its most interesting secrets hidden in the clouds.

Solar system quiz: How well do you know our cosmic neighborhood?

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Astronomers have solved the mystery of how some stars stay youthfully bright and blue, despite being almost as old as the universe itself: They cannibalize their stellar siblings.

Known as blue straggler stars, these age-defying celestial objects have mystified astronomers for more than 70 years. "Blue stragglers are anomalously massive core hydrogen-burning stars that, according to the theory of single star evolution, should not exist," researchers wrote in a paper published Jan. 3 in the journal Nature Communications.

To investigate these puzzling stars, researchers used the James Webb Space Telescope (JWST) to analyze 48 galactic globular clusters and more than 3,400 blue straggler stars in the Milky Way. Their observations revealed that these "forever young" stars stay youthful by siphoning the gas from their partners, like stellar vampires. This fuel injection allows the vampire stars to shine more brightly, and to appear more blue and youthful, long after they should have started fading away.

Searching for age-defying stars

Scientists previously posited that blue stragglers can form in two ways: through violent collisions between two stars, or through more subtle interactions in binary systems as pairs of stars orbit each other and trade gas.

The team found that the latter scenario is more likely.

Galactic globular clusters provide the perfect place to study stellar interactions between gas-siphoning binary systems. These spherical clusters contain thousands or millions of stars, held together by their collective gravity. With so many stars inhabiting a region only tens or hundreds of light-years across, clusters are among the most dense stellar environments in the cosmos. Therefore, they host many stellar collisions and plenty of binary systems.

Clusters are also incredibly ancient. "Their age is of the order of 12 [billion years], hence comparable to the age of the Universe," which is 13.8 billion years old, Francesco Ferraro, lead author of the study and an astronomy professor at the University of Bologna in Italy, told Live Science via email. "In fact they are the oldest population in our Galaxy." This means the single stars in each cluster hosting the blue stragglers formed at the epoch of galaxy formation.

Older stars also emit different wavelengths of radiation. So the researchers utilized JWST's ultraviolet filters to distinguish blue stragglers from their elderly cluster-mates — because hotter -- younger stars emit more radiation at shorter wavelengths than older, redder populations that emit poorly in this part of the electromagnetic spectrum.

A surprising stellar scenario

Perhaps counterintuitively, the researchers found that blue stragglers are rarer in dense stellar environments, even though these regions are more likely to facilitate interactions between stars. Instead, stragglers are significantly more common in calm, low-density regions where stars are spaced farther apart and "fragile binary systems are more likely to survive."

The researchers used an established, quantitative measure that relates the number of blue stragglers to the host cluster's characteristics, like luminosity. This measure revealed that blue straggler populations vary greatly, from three to 58 blue stragglers per unit of luminosity — equivalent to the brightness of 10,000 suns. Accordingly, luminosity is related to a cluster’s overall mass and, therefore, its density.

Using that same measure, the researchers calculated that the number of regular stars in a cluster remains relatively constant. This suggests that stragglers and binary systems are especially sensitive to the density of their environments.

"Crowded star clusters are not a friendly place for stellar partnerships," study co-author Enrico Vesperini, an astronomer at Indiana University, said in a statement. "Where space is tight, binaries can be more easily destroyed, and the stars lose their chance to stay young."

Therefore, dense environments, such as those nearer the centers of clusters, may not be the stellar speed-dating venues they were assumed to be. The gravitational influences from large stellar populations create a cosmic-bumper-car-like effect that disrupts binary systems early in their evolution, before they can turn into blue straggler stars. As a result, the formation and survival efficiency of stragglers is 20 times higher in calmer, low-density environments, the researchers found.

A new way to understand stellar evolution

In addition to solving an astronomical mystery, this study offers a "new way to understand how stars evolve over billions of years," study co-author Barbara Lanzoni, an astronomer at the University of Bologna, said in the statement.

But after billions of years, blue stragglers may not get to live out their quiet lives in peace. Because they are significantly more massive than their sibling stars, they are more likely to sink to the core of their clusters through a process called dynamical friction. Although this is unfortunate for these calm-loving stars, astronomers can then use them as a "dynamical clock" to extrapolate a cluster's age based on the distribution of its blue stragglers.

Finally, these sprightly, fresh-faced stars highlight a dynamic stellar balance. Had they been born more massive, they would have died long ago as supernovas or white dwarfs. Their modest size, below 0.8 solar masses, have allowed them to survive long enough to renew their lifespans — at the cost of consuming their siblings.

An artificial intelligence (AI) tool has uncovered more than 1,000 strange cosmic objects in the Hubble Space Telescope's image archive, including some that cannot be explained by science.

After searching with the tool for just two days, researchers found 1,300 oddball objects, including chaotic merging galaxies, stars trailing gas, and even some objects that haven't been classified yet. Of these, 800 had never been spotted before, European Space Agency (ESA) officials said in a Jan. 27 statement. The findings were published Dec. 16, 2025, in the journal Astronomy & Astrophysics.

"Additional discoveries included galaxies with massive star-forming clumps, jellyfish-looking galaxies with gaseous 'tentacles,' and edge-on planet-forming disks in our own galaxy resembling hamburgers," NASA officials said in a separate statement. “Remarkably, several dozen objects defied existing classification schemes entirely."

Space jellies and sky burgers

For the new study, ESA research fellows David O'Ryan and Pablo Gómez developed an AI tool to examine 100 million image cutouts from the Hubble Legacy Archive, which covers the telescope's observations following its 1990 launch. Each of the images was only a few dozen pixels per side, representing a narrow slice of sky barely a thousandth of a degree wide.

"Archival observations from the Hubble Space Telescope now stretch back 35 years, providing a treasure trove of data in which astrophysical anomalies might be found," O'Ryan wrote in the paper.

In addition to the "jellyfish galaxies" and cosmic "hamburgers," the search uncovered a range of other phenomena. "Most of the anomalies were galaxies undergoing mergers or interactions, which exhibit unusual morphologies or trailing, elongated streams of stars and gas," according to the NASA statement. "Others were gravitational lenses, where the gravity of a foreground galaxy distorts spacetime and bends light from a background galaxy into arcs or rings."

The researchers' AI tool, called AnomalyMatch, picked up these features after learning patterns from a training dataset. Using tools like this speeds up the traditional means of discovering strange things in the sky, which usually requires manual inspection or a lucky observation.

"While expert astronomers excel at identifying unusual features, the sheer volume of Hubble data makes comprehensive manual review impractical," NASA officials said in a statement. "Citizen science initiatives have helped expand the scope of data analysis, but even these efforts fall short when faced with archives as extensive as Hubble's."

"This is a powerful demonstration of how AI can enhance the scientific return of archival datasets," Gómez added. "The discovery of so many previously undocumented anomalies in Hubble data underscores the tool's potential for future surveys."

More datasets where AI may be useful include those from the Euclid space telescope, which is surveying billions of galaxies to create the largest 3D map of the universe ever, and the forthcoming Nancy Grace Roman Telescope and the Vera C. Rubin Observatory, which will hunt for exoplanets and moving objects across vast stretches of the night sky. AI could help researchers sort through the "data deluge" from these large surveys, perhaps allowing for faster pickups of new objects than ever before, according to the NASA statement.

The James Webb Space Telescope (JWST) has revealed a hidden "doomed" star that could help solve a giant astrophysical mystery.

The star is a massive red supergiant, which JWST snapped just before the star exploded in a fiery supernova. Massive red supergiants should, in theory, cause most supernovas, but they're rarely observed. The latest JWST observation, described in a new study published Wednesday (Oct. 8) in The Astrophysical Journal Letters, adds weight to the idea that these giants are often obscured by clouds of dust.

"For multiple decades, we have been trying to determine exactly what the explosions of red supergiant stars look like," study lead author Charlie Kilpatrick, a research assistant professor studying massive stars at Northwestern University in Illinois, said in a statement. "Only now, with JWST, do we finally have the quality of data and infrared observations that allow us to say precisely the exact type of red supergiant that exploded and what its immediate environment looked like."

Stars around the size of our sun swell up near the end of their lifecycles to become red giants before going supernova. Red supergiants are massive stars on the verge of detonating, typically measuring hundreds or thousands of times larger than our sun.

The All-Sky Automated Survey for Supernovae first detected the supernova from the newly imaged supergiant in June. The supernova, officially named SN 2025pht, came from a galaxy called NGC 1637, which is located 38 million light-years from Earth — pretty close for something in space. The authors of the new study identified the supergiant's source star (its progenitor) by comparing historical Hubble Space Telescope data to new JWST images of NGC 1637 taken before and after the explosion.

Researchers like Kilpatrick have suggested that the most massive aging stars might also be the dustiest, so their light is blocked. This possible explanation tracks with the new JWST observation. The star shone about 100,000 times brighter than our sun, but the team estimated that its dust was so thick that this light was made more than 100 times dimmer, according to the statement.

The dust was also particularly effective at blocking shorter, blue wavelengths of light. Fortunately, JWST's powerful infrared detection could see the longer red wavelengths, providing an unprecedented detailed look at a supergiant on the brink of going supernova.

"SN2025pht is surprising because it appeared much redder than almost any other red supergiant we've seen explode as a supernova," Kilpatrick said. "That tells us that previous explosions might have been much more luminous than we thought because we didn't have the same quality of infrared data that JWST can now provide."

Here’s a story for the ages — or maybe a story of the ages.

The Hubble Space Telescope’s latest image, of barred spiral galaxy NGC 6000, is rich in yellow at its center and blue on its outskirts, but it’s what these colors reveal about the ages, masses and temperatures of the galaxy’s stars that makes the portrait truly fascinating.

The yellow tells the story of the center of NGC 6000, where stars are old, small and relatively cool. These stars have been shining for billions of years. In astronomy, cool stars are red, while the hottest stars are blue. The latter dominate the outskirts of this galaxy, where its spiral arms are filled with stars that are younger, hotter and larger. These stars are cosmic newborns.

The image, which is also available as a panning video, was produced while Hubble searched for supernova explosions — hence the incomplete framing. The aging space telescope targeted the faint glow of supernovas called SN 2007ch and SN 2010as, stars that exploded in 2007 and 2010, respectively.

However, while imaging NGC 6000, Hubble also captured something else entirely. Look on the right-hand side of the image, and four faint broken lines can be seen — the path of an asteroid that drifted across Hubble’s field of view as it took four long-exposure images of NGC 6000. The broken lines are red and blue because Hubble used red and blue filters to collect visible light, which makes it easier for astronomers to compare stars by their colors.

Although it’s in the constellation Scorpius, which is visible in summer from the Northern Hemisphere, NGC 6000 lies south of the celestial equator, according to The Sky Live. That means it’s more easily visible from the Southern Hemisphere. However, to glimpse it requires at least a 10-inch aperture telescope and a dark sky.

For more sublime space images, check out our Space Photo of the Week archives.

Astronomers are scratching their heads after detecting a bizarre, long-lasting cosmic explosion unlike anything previously observed.

The explosion was a series of repeated outbursts of high-energy radiation, known as a gamma-ray burst. These bursts, the most powerful known explosions in the universe, typically only last for milliseconds to minutes, yet this one was observed erupting for nearly an entire day in July.

Scientists can't explain the record-shattering duration of the event, which occurred outside of the Milky Way and is officially named GRB 250702BDE, according to a study published Aug. 29 in The Astrophysical Journal Letters. Gamma-ray bursts are usually caused by the death of a giant star, but they're typically singular events. This one is unlike any other in 50 years of gamma-ray burst (GRB) observations, according to study co-lead author Antonio Martin-Carrillo, an astrophysicist at University College Dublin.

"GRBs are catastrophic events so they are expected to go off just once because the source that produced them does not survive the dramatic explosion," Martin-Carrillo said in a statement. "This event baffled us not only because it showed repeated powerful activity but also because it seemed to be periodic, which has never [been] seen before."

Related: 'It gave me goosebumps': Most powerful gamma ray burst ever detected hid a secret, scientists say

NASA's Fermi Gamma-ray Space Telescope first recorded the burst on July 2. Researchers then discovered that the Einstein Probe, an X-ray space telescope run by the Chinese Academy of Sciences with European partners, had detected activity from it on July 1, almost a day earlier.

To study the burst in more detail, a team at the European Southern Observatory (ESO) turned to the Very Large Telescope, one of the world's most advanced optical telescopes located in Chile’s Atacama desert. While originally thought to have occurred inside our galaxy, the Very Large Telescope observations suggested the strange signal had come from beyond it, an observation later confirmed by the Hubble Space Telescope, according to the study.

The study authors explored several possible explanations for the unprecedented repeated explosion.

"If a massive star – about 40 times the mass of the Sun – had died, like in typical GRBs, then it had to be a special type of death where some material kept powering the central engine," Martin-Carrillo said.

Another possible explanation is that the radiation blasts were emitted when a star, potentially a white dwarf, was ripped apart by a black hole in what's known as a tidal disruption event (TDE). But in order to produce the continuing explosion, this wouldn't have been any ordinary black hole.

"Unlike more typical TDEs, to explain the properties of this explosion would require an unusual star being destroyed by an even more unusual black hole, likely the long-sought 'intermediate mass black hole,'" Martin-Carrillo said. "Either option would be a first, making this event extremely unique."

Intermediate-mass black holes are larger than the stellar-mass black holes (formed when massive stars collapse in on themselves) but smaller than the supermassive black holes at the center of most galaxies. Astronomers expect that stellar-mass black holes collide and merge over time to form intermediate-mass black holes, but they've proven incredibly difficult to locate.

The team behind the new study is monitoring the aftermath of the explosion and deciphering its cause. The next step will be determining the precise location of the explosion, which will help researchers measure how much energy it generated.

"We are still not sure what produced this or if we can ever really find out but, with this research, we have made a huge step forward towards understanding this extremely unusual and exciting object," Martin-Carrillo said.

Black hole quiz: How supermassive is your knowledge of the universe?

Astronomers have discovered an incredibly rare system in which at least five galaxies from the early universe are merging — just 800 million years after the Big Bang. The remarkable discovery was made using data from the James Webb Space Telescope (JWST) and the Hubble Space Telescope.

Galaxy mergers play a key role in galaxy formation in the early universe. While not commonly seen, merging systems do occur, typically involving two galaxies. However, the newly identified merger, nicknamed JWST's Quintet, contains at least five galaxies and 17 galaxy clumps.

"Finding such a system with five physically linked galaxies is exceptionally rare, both in current simulations and in observations," said study lead author Weida Hu, a postdoctoral researcher at Texas A&M University. "The probability of detecting even one [multiple-galaxy merger] is quite low, which raises the possibility that we may have been 'lucky' in identifying this system so early," Hu told Live Science in an email.

These galaxies are called emission-line galaxies as they have prominent signatures in their light, particularly those emitted by hydrogen and oxygen, which are telltale signs of new stars forming.

The power of two

The research, published Aug. 15 in the journal Nature Astronomy, used a combination of JWST and Hubble data.

JWST's Near-Infrared Camera (NIRCam)hinted at a large halo of gas around the group of galaxies, which meant that the five galaxies are not independent but are instead physically connected and embedded in the same system, Hu explained.

Related: James Webb telescope images reveal there's something strange with interstellar comet 3I/ATLAS

While some of these galaxies were previously detected using Hubble, "only JWST data tell us that the five galaxies have the same redshift and are interacting with each other," Hu added. (Redshift is a measure of cosmic distance, with higher redshifts corresponding to more distant, ancient objects. Redshift occurs as the light emitted by distant objects stretches into longer, redder wavelengths while crossing the expanding universe.)

Hu suggested that there could be other faint or hidden galaxies linked to JWST's Quintet that have not yet been detected. But discovering these galaxies may require advanced multi-wavelength observations.

Early universe mergers involving more than two galaxies are extremely rare, said Christopher Conselice, a professor of extragalactic astronomy at the University of Manchester who was not involved in the study.

"If you look at all galaxies, then 20-30% of them will be in a merger. This will be just two galaxies. The fraction of these multiple merger systems will be much, much lower, and we don't have stats on it quite yet, but certainly lower than 1%," Conselice told Live Science.

The team found that the two main galaxies in the system appear to be separated by a distance of 43,300 light-years, and the most distant pair among all the galaxies in the system appear to be 60,700 light-years apart. (For comparison, our Milky Way galaxy is about 100,000 light-years end to end.)

"The fact that the galaxies are spatially close together is the indication that they probably will merge," Conselice said. "There is some room for interpretation regarding whether some objects might be parts of the same galaxy," he added.

The distant cousin

This system is similar to its local universe counterpart, Stephan’s Quintet, which is a merger of four galaxies, with a fifth galaxy that appears in the same part of the sky but isn't merging.

"A striking similarity is the presence of a bridge of material connecting two galaxies in JWST's Quintet — a feature also seen in Stephan’s Quintet, indicative of tidal tails produced by the galaxy interaction,” Hu said. "However, the star formation rate of JWST's Quintet is much higher."

While all the galaxies in Stephan’s Quintet are much older systems in the nearby universe, and therefore are less active, the galaxies in JWST's Quintet are rich in gas and are vigorously forming new stars at a rate higher than expected for that period.

JWST's Quintet, with at least five galaxies and 17 galaxy clumps, has a total stellar mass of 10 billion suns. The study suggests that the high mass and star formation rate indicate that the galaxies in the merger may evolve into a massive quiescent galaxy, occurring approximately 1 billion to 1.5 billion years after the Big Bang. Quiescent galaxies are those that stop forming new stars. Previous JWST studies have detected several of them in the early universe, which raised questions about how galaxies could become "dead" so early in the universe.

Conselice said that the future of merging galaxies is a big question. They might end up as star-forming galaxies but with less activity, or they could just become "dead" or passive over time. The future of the system will also depend on whether the galaxies host actively feeding black holes, which may nudge the system to extinguish star formation very quickly.

If the merging galaxies turn into a dead system, JWST's Quintet could potentially explain how massive quiescent galaxies can form rapidly through the merger of smaller, starbursting galaxies in the early universe.

Hu noted that JWST's NIRCam images show clear details of shapes and structures of the objects, but they do not offer precise information like the intensity of spectral lines. Without these spectroscopic details, it's hard to accurately measure properties such as metallicity, motion and dynamics of the system, or the nature of the gas inside these galaxies and clumps.

If more systems like JWST's Quintet are found in future JWST surveys, researchers can study how often these merging groups of galaxies appear, their nature, and examine the conditions in which they form. This will enable researchers to verify whether these systems belong to a rare class that the current standard model of the universe predicts, or if they suggest new mechanisms in action.

The James Webb Space Telescope's (JWST) latest extragalactic survey has revealed fainter and more distant objects than ever before, some dating back to the earliest periods of the universe. But it stands on the shoulders of a giant: When NASA published the Hubble Ultra Deep Field image in 2004, it stunned the world of astronomy. A composite of 800 images from exposures totaling 11 days, the deep image of an otherwise unremarkable part of the night sky revealed nearly 10,000 galaxies, many among the most distant known.

Now, JWST has observed that same patch of sky with different eyes — and found 2,500 more objects. Crucially, they're even more distant.

JWST's new take on the Hubble Ultra Deep Field, named the MIRI Deep Imaging Survey (MIDIS), is the deepest-ever mid-infrared image of that part of the night sky.

The extraordinary new image is the result of nearly 100 hours of observing time using the space observatory's Mid-Infrared Instrument (MIRI) and Near-Infrared Camera (NIRCam). It includes hundreds of extremely red galaxies, some of which may date back to less than a billion years after the Big Bang.

Related: 42 jaw-dropping James Webb Space Telescope images

At the core of the composite image is one ultralong exposure. Using just one of MIRI's filters, JWST took an exposure of the night sky for 41 hours — the longest single-filter observation it has performed of an extragalactic field to date. The plan was to capture galaxies in mid-infrared light — something neither Hubble nor human eyes can detect — which also revealed previously unseen regions of dust and old, red stars.

Capturing light in wavelengths beyond the capabilities of human vision always brings a problem: How can we even begin to look at it? Processing such images requires filters that assign a different color to each different wavelength of light. In this image, galaxies rich in dust and star-forming activity are orange and red, extremely distant compact galaxies are greenish, and galaxies bright in the near-infrared are blue and cyan.

Researchers described the image in a paper in the journal Astronomy & Astrophysics, along with a slider tool, a pan video and a transition video with the Hubble Ultra Deep Field for comparison.

For more sublime space images, check out our Space Photo of the Week archives.

NASA has revealed the most detailed images yet taken of comet 3I/ATLAS, the interstellar visitor that is currently barreling its way through our solar system.

The images, taken by NASA's Hubble Space Telescope, have enabled astronomers to more accurately estimate the space object's size — and it looks like it's smaller than we thought, NASA said in a statement.

3I/ATLAS was first discovered on July 1, and the next day it was confirmed by NASA to have originated from outside of our solar system. The extrasolar entity is hurtling toward the inner solar system at speeds of more than 130,000 mph (210,000 km/h) and is expected to reach its closest point to the sun in late October. (The object poses no threat to us, and will be on the far side of the sun during its close approach).

It is only the third such interstellar object to have been detected in our solar system, and astronomers are still scratching their heads as to where it came from and what it is made of.

"No one knows where the comet came from," David Jewitt, an astronomer at UCLA and science team leader for the Hubble observations, said in the statement. "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."

Related: 3I/ATLAS: Everything you need to know about the new 'interstellar visitor' shooting through the solar system

At the end of July, the newly operational Vera C. Rubin Observatory estimated that the alien comet was roughly 7 miles (11.2 kilometers) wide across its icy nucleus. Now, Hubble's images have suggested that the nucleus is probably closer to a maximum of 3.5 miles (5.6 km) across, which would still make it the largest interstellar object ever spotted. On the low end, NASA estimates the comet to be no smaller than 1,000 feet (320 meters) across — but planned observations with the James Webb Space Telescope and other NASA observatories will further hone these numbers as the comet gets closer over the coming months.

The two other known interstellar objects that have blown through our solar system are 1I/'Oumuamua, which was discovered in 2017, and 2I/Borisov, which was spotted in 2019. 'Oumuamua, an asteroid, is believed to have been around 0.2 miles (0.4 km) wide), while Comet Borisov has a nucleus measuring roughly 0.6 miles (1 km) wide — making both significantly smaller than the upper estimates for 3I/ATLAS.

Researchers hope that by studying these alien objects we can learn more about distant star systems and the characteristics of the exoplanets that orbit within them.

"Each one of these ISOs [interstellar objects] is a little piece of low-hanging fruit from a tree that can tell us a great deal about the trees growing in some other neighborhood," Wes Fraser, an astronomer with National Research Council Canada, previously told Live Science.

ANCHORAGE, Alaska — The Trump administration has been disrupting the infrastructure of U.S. science over the last few months, its latest blow being a 2026 budget proposal that would cut NASA's science funding in about half. If passed by Congress, this budget would be devastating, scientists say. It would cancel a number of in-development and currently operational missions, lead to significant layoffs and force the shutdown of some astronomy facilities.

"It basically slashes science just about everywhere," Neill Reid, the multi-mission project scientist at the Space Telescope Science Institute (STScI) in Baltimore, said during the 246th meeting of the American Astronomical Society (AAS) here last month. "NASA science is cut by a factor of two; astrophysics is cut by two-thirds."

This situation therefore begs the question: How might Trump's proposed reductions in U.S. science funding domino down to two of the most high-profile astronomy instruments we have, the Hubble Space Telescope (HST) and James Webb Space Telescope (JWST)?

The short (and glass-half-full) answer is that Trump's fiscal year 2026 budget request doesn't outright cancel the JWST or the HST. The reductions suggested for these instruments are also rather modest relative to those suggested for other projects (not to mention the missions that'd be deleted from the roster altogether, like the Jupiter-orbiting Juno spacecraft).

Still, the JWST's funding would go down from the $187 million it was allocated in 2024 to $140 million for 2026 if the budget gets passed. Hubble's funding would go down from the $93.3 million it had in 2024 to $85 million in 2026. And both of these proposed reductions would certainly affect these cosmic imagers.

Less money, fewer stars

To start with the JWST, Reid says a 25% to 35% reduction in operations could be in store for the $10 billion telescope that lives about a million miles away from Earth.

"The operations costs for JWST were set back in 2011; there was a certain amount of optimism that went into some of those," he said. "There's also been inflation; then you have the [President's budget request] that comes in and cuts more."

A slide in Reid's presentation also stated that "inflation and NASA budget issues are [a] significant risk to JWST support starting Oct 2025." That general support would be needed now more than ever, he explained, seeing as how demand for the JWST has only continued to increase ever since it began observing the cosmos in mid-2022.

With regard to Hubble, Reid pointed out that the telescope's budget has remained "flat" for the past 10 years, which means the team has lost about 30% spending power on the spacecraft already due to inflation: "Essentially, we're now at the point where if you cut the budget further, which is what is proposed here, you end up being able to do less."

To be fair, discussions regarding Hubble funding precede the Trump administration's proposed budget cuts — last year, for instance, an independent panel of experts convened to review what the future of Hubble budgets will look like as the telescope faced a possible 10% cut to its budget under the Biden administration. The Hubble Space Telescope's orbit is also naturally getting lower and lower as the years go by; NASA isn't quite sure yet whether a boosting mission is worth the technology, time and effort (though it's not 100% out of the question).

"The main takeaway for Hubble is that she's in great health. There's a high probability of producing great astrophysics into the early 2030s. The orbit is decaying — we know that — but the median estimate of the entry point [into Earth's atmosphere] is September of 2033."

With Trump's proposed Hubble cut, Reid said some of the telescope's instruments would remain "unsupported" in Earth orbit even if they're able to stay online. He said there's work being done at the moment in a sort of "close-out" to make sure Hubble can have as much support as possible, but that the team will be relying on the community to "self-support" while using those particular instruments.

"The bottom line here is, we're not going to do anything about it until we get formal direction from NASA," he said. "We're preparing … but until NASA tells us 'you need to stop doing something,' we're going to keep doing it."

"I think it is up to us to push back and emphasize the importance of NASA science leadership to our representatives," he added. "You can even tell them that science makes America safer, stronger and more prosperous."

It's a sentiment that was echoed by many at the AAS conference, especially because many scientists are being pressured to not speak out by their institutions for fear of retaliation.

Grants, telescope synergy and the White House

For scientists, some of the most serious consequences of Trump's 2026 budget request have to do with grant funding being significantly reduced. Though it's great to have an operational telescope in space, that telescope isn't of much use if scientists can't create instructions for it.

And those instructions stem from scientific studies, which are funded by grants.

"There's also going to be less money that will go into high-level science products in MAST [which is an astronomy data archive]," Reid said, "and there will be less grant funding."

"That's going to affect, basically, things across the board," he added. "We don't have a specific plan here yet. We'll keep the community informed."

Reid also touched on the importance of publicity for both Hubble and JWST science — something that has indeed been affected by Trump cuts already. "Publicity" in this sense refers to, for instance, the article you're reading right now. Media communications from scientific institutions — including NASA, the National Oceanic and Atmospheric Administration (NOAA) and others that have seen reductions in this sector — allow journalists to learn about research timelines, outcomes and hurdles so they can be explained to the public. This is a key aspect of the scientific process.

"Publicity is something that lets the taxpayer know how we are spending money; what we are doing with it," he said.

Additionally, it can't be ignored that a major purpose of science is to further humanity's knowledge and prospects, meaning humanity should know about the discoveries that are fueling this goal. It is only then when scientific observations can lead to breakthroughs in other disciplines, form the next generation of scientists and procure art that cyclically inspires scientists themselves.

"I mean, there's the Universe of Learning. That's a consortium of different organizations we're part of. It provides materials for museums, for planetariums. Their grant finishes at the end of this year. It's not being renewed," Reid said. "This is something that we're going to need to look at critically in the future — make sure that we can still tell people what we do so we have some support out there for continuing doing it."

And in fact, both the JWST and Hubble are veterans at strengthening the bond between scientific research and public discourse. Both can create visual expanses that make the unimaginable universe seem a little more coherent and tangible while somehow normalizing concepts once confined to fantasy.

"There's a strong synergy between what Hubble does at UV [ultraviolet] wavelengths, and what Webb does at near-infrared," Reid said. "I'm still blown away by the fact that we're kind of blasé now about redshift 13 galaxies."

(Redshift 13 galaxies are those that existed over 13 billion years ago, when the cosmos was still in its infancy. Thanks to the JWST, we can literally look at them today.)

"The Rocky World project is putting together the best aspects of JWST and HST," Reid said. "This is an exciting program that really has a good chance of telling us whether M-dwarf planets [those circling red dwarfs, the most common stars in the Milky Way] are a good place to look for signs of life."

He also mentioned how excellent the results can be when the JWST and Hubble team up with the Chandra X-ray telescope — yet another NASA facility on the chopping block. Trump's 2026 fiscal year budget proposal takes Chandra from its allocated $70 million in 2024 to $0 for 2026.

"Habitable Worlds Observatory, Hubble 2.0, is the next big thing that NASA's aiming for. It was not written out of the [President's budget request]. It's still in there, much reduced, but it's still in there.

"That's good."

This article was originally published on Space.com.

Why it's so special: What if a galaxy had only one spiral arm?

Our solar system resides on the outskirts of one of the Milky Way galaxy's estimated four spiral arms, according to Space.com, but not all galaxies are like that. In the latest image from NASA's Hubble Space Telescope, a strange galaxy called NGC 1961 comes into focus that has just one — a single broad, star-speckled spiral arm that appears to stretch toward us as the galaxy is viewed from a skewed angle.

It may seem a dramatic point of view, but it's merely what Hubble sees from its line of sight on its orbital path around Earth. On the far side of the newly imaged galaxy, beyond swirls of stars and dust around a bright center, there is no similarly impressive spiral arm, with just a few wisps of gas and stars instead. The image is also available as a panoramic video, a zoomable version, and as a 15-megapixel download.

Its sole spiral arm long ago earned NGC 1961 the additional name Arp 184 and a place in the Atlas of Peculiar Galaxies, a catalog of galaxies that are neither perfectly symmetrical spiral galaxies nor smooth, spherical elliptical galaxies. First published in 1966 by American astronomer Halton Arp, the atlas collects 338 galaxies that are oddly shaped, many because they're interacting with other galaxies. Others in the atlas are dwarf galaxies in flux.

Related: James Webb telescope's observations of 'impossible' galaxies at the dawn of time may finally have an explanation

There's another reason why Hubble targeted Arp 184/NGC 1961. It's hosted four known supernovas — the powerful explosion of a dying star — in the past four decades (in 1998, 2001, 2013 and 2021). It's exceptionally rare to catch a supernova in the act, so galaxies with a proven track record like this one make prime targets.Arp 184/NGC 1961 was discovered by German-British astronomer William Herschel in 1788, seven years after he discovered the planet Uranus, the first planet to be found in modern times.

According to observations from NASA's Spitzer Space Telescope, the Milky Way has two main spiral arms — the Perseus and Scutum-Centaurus arms — and two less obvious arms, the Sagittarius and Norma arms. Two minor spiral arms are close to the galaxy's center, the Far-3 kiloparsec arm and the Near-3 kiloparsec arm. Our solar system exists in the Orion Spur between the Sagittarius and Perseus arms.

For more sublime space images, check out our Space Photo of the Week archives.

There are few more iconic images from the Hubble Space Telescope than this one. A colossal pillar of gas and dust towering 9.5 light-years tall, this spectacular structure in the Eagle Nebula highlights the breathtaking beauty sculpted by the forces of star formation.

The stunning image, originally published in 2005, is an important part of why the Hubble is so loved. The photo has been newly processed using modern techniques to show the "cosmic pillar" in even more detail, with layers of cold gas and dust seen by Hubble's visible and infrared cameras.

The new image more clearly shows how the radiation from the hot, young stars in the more dramatic top half of the image is lighting up — but also eroding — the massive tower. The image covers an area equal to twice the distance from the sun to Alpha Centauri, the closest star system to our own.

Related: Stunning 'pillars of creation' shine like never before in new James Webb Telescope image

If you think this newly minted snapshot looks a bit like an even more famous Hubble image, the iconic Pillars of Creation, there's a reason for that. Hubble's images of three towers of cosmic dust and gas that resemble a pointing finger — first released in 1995 and improved upon in 2015 to mark Hubble's 25th anniversary — are relatively nearby in the Eagle Nebula (M16). In fact, both images are of dust pillars around the edge of the nebula's heart, where the radiation from a cluster of young stars called NGC 6611 has sculpted a cavity in the dusty gas.

Serpens is prominent in the night sky during the Northern Hemisphere's summer. It can be found in the south, between the bright stars Aquila and Antares and beneath the constellation Ophiuchus, the Serpent Bearer.

This photo of M16 is the latest redux image published to mark the 35th anniversary of the Hubble Space Telescope, which launched on the space shuttle Discovery on April 24, 1990 and was released from the cargo hatch the following day. Earlier this month, new images revisiting NGC 346 and the Sombrero Galaxy were published.

For more sublime space images, check out our Space Photo of the Week archives.

A day on Uranus is about half a minute longer than previously thought, according to new research.

An analysis of 11 years of Hubble Space Telescope observations shows that Uranus' day lasts 17 hours, 14 minutes, and 52 seconds. That's 28 seconds longer than NASA's Voyager 2 spacecraft estimated when it passed Uranus in 1986. Researchers reported the updated estimate April 7 in the journal Nature Astronomy.

Nearly 40 years ago, Voyager 2 became the first spacecraft to observe Uranus up-close. Using radio signals from the planet's auroras and magnetic field data collected by the spacecraft, astronomers at the time found that Uranus' day lasted approximately 17 hours, 14 minutes and 24 seconds.

Researchers used that rotation period to define a coordinate system for the planet. But the measured period came with an inherent uncertainty of about 36 seconds, which gradually added up as each Uranian day passed. Within a few years, the uncertainty made it impossible to accurately determine the orientation of the planet's magnetic axis.

To get more reliable estimates of the planet's rotational period, the authors of the new study tracked the movement of auroras at Uranus' magnetic poles from six sets of Hubble observations taken between 2011 and 2022. This helped them refine the locations of the planet's magnetic poles, which they used to work out a more accurate estimate of Uranus' rotational period. The new measurement has an uncertainty of less than 0.04 seconds, according to the team.

"The continuous observations from Hubble were crucial," first study author Laurent Lamy, an astronomer at the Paris Observatory, said in a statement. "Without this wealth of data, it would have been impossible to detect the periodic signal with the level of accuracy we achieved."

Related: 'Hidden' rings of Uranus revealed in dazzling new James Webb telescope images

The 28-second difference is within the margin of error of Voyager 2's calculation, but the new duration has a much lower uncertainty. "It's not so much that it's changed," Tim Bedding, an astronomer at the University of Sydney in Australia, told New Scientist. "It's now accurate enough to be more useful."

With this smaller uncertainty, the coordinate system based on the new measurement of Uranus' rotational period should hold up for several decades, the team said. Future missions to Uranus, such as the proposed Uranus Orbiter and Probe, could rely on this coordinate system when selecting an atmospheric entry site, the researchers wrote in the study.

"With this new longitude system, we can now compare auroral observations spanning nearly 40 years and even plan for the upcoming Uranus mission," Lamy said in the statement.

What it is: The spiral galaxy UGC 5460

Where it is: 60 million light-years away in the constellation Ursa Major

When it was shared: Feb. 21, 2025

Why it's so special: This stunning new image of a spiral galaxy — and a very bright star above it — was recently captured by the Hubble Space Telescope. The image shows the galaxy's central bar of stars, along with its spiral arms and young, blue star clusters. The top-left of the image, meanwhile, is dominated by a star that's just 577 light-years away in the Milky Way.

This galaxy has hosted two significant supernova explosions in the last 14 years. Such events are landmarks for astronomers and are the final, destructive stage for some massive stars. A supernova explosion can briefly have the power of up to 100 billion stars and temporarily outshine their host galaxies.

Supernovae play a vital role in spreading heavy elements around interstellar space, which in turn sparks the formation of new stars.

Related: The 10 biggest explosions in history

These stellar explosions may be inevitable for some classes of stars, but they can play out in wildly different ways — which scientists suspect is the case for the two recent supernovas that erupted in this picturesque spiral galaxy.

For example, in 2015, astronomers watched the star SN 2015 explode as a "core-collapse" supernova, when the massive star consumed its nuclear fuel and collapsed under gravity, causing its outer layers to be ejected into UGC 5460. This explosion led astronomers to take the new image of the galaxy, as they wanted to find out how a supernova's shock wave interacts with the interstellar gas surrounding it.

An earlier supernova explosion in 2011, meanwhile, called SN 2011ht, initially appeared to be a core collapse. However, astronomers suspect that it may be a so-called "luminous blue variable" — a rare kind of massive star that outbursts like a supernova but leaves the star intact. Hubble is now looking for the surviving star at the explosion site.

This detailed image of UGC 5460 from Hubble's Wide Field Camera combines data from the ultraviolet, near-infrared and visible light parts of the spectrum.

The galaxy is found close to the stars Merak and Dubhe on the outside of the bowl, in the shape of the Big Dipper/Plough asterism in the night sky, though it is too dim to see with anything other than large professional astronomy telescopes.

For more sublime space images, check out our Space Photo of the Week archives.

An ambitious new survey by the Hubble Space Telescope provides the first-ever bird's-eye view of all known dwarf galaxies orbiting the Andromeda galaxy.

The results reveal that over billions of years, Andromeda and its family of dwarf galaxies have experienced markedly chaotic interactions — like a game of bumper cars — compared with the relatively placid evolution of the galaxies circling the Milky Way.

The findings, published in The Astrophysical Journal, demonstrate that we may not be able to extrapolate information about other galaxies from our understanding of our own galaxy, the study authors said.

"There's always been concerns about whether what we are learning in the Milky Way applies more broadly to other galaxies," study co-author Daniel Weisz, an associate professor of astronomy at the University of California, Berkeley, said in a statement. "Our work has shown that low-mass galaxies in other ecosystems have followed different evolutionary paths than what we know from the Milky Way satellite galaxies."

At about 2.5 million light-years away, Andromeda is the closest major galaxy to our own, and getting closer; Andromeda and the Milky Way are predicted to collide and merge in about 5 billion years time. To the naked eye, it appears as a faint, spindle-shaped object that covers about the same amount of sky as the full moon. What isn't visible without powerful telescopes and is not well studied is the swarm of three dozen smaller galaxies scattered around Andromeda, like bees around a hive.

Related: The Andromeda Galaxy glows rosy red in gorgeous new Hubble Telescope image

Starting in late 2019, Hubble spent two years cataloging images — as well as measurements of the locations and motions — of three dozen galaxies swirling up to 1.63 million light-years from Andromeda. These data provided Weisz and his team the first comprehensive 3D map of our galactic neighbor's ecosystem. Using this information, the researchers studied the processes that drove the evolution of these dwarf galaxies over nearly 14 billion years of cosmic time.

"Everything scattered in the Andromeda system is very asymmetric and perturbed," Weisz, principal investigator of this Hubble program, said in the statement. "It does appear that something significant happened not too long ago."

That something, the researchers posit, was a collision between Andromeda and a large galaxy a few billion years ago. The possible culprit could be Messier 32, a satellite galaxy of Andromeda and its brightest companion. Astronomers suspect that M32, which is visible to Andromeda's bottom left, is the remnant core from the merger.

"No one knows what to make of that"

Analysis of the Hubble observations also revealed a unique population of galaxies around Andromeda that has not been observed around the Milky Way, according to the new study.

This group began forming most of its stars early on and continued to do so at extremely low rates and for much longer than astronomers would expect. Given the intense gravitational pull of Andromeda, these galaxies should have been stripped of their star-forming gas long ago, similar to what is observed around the Milky Way.

"This doesn't appear in computer simulations," study lead author Alessandro Savino, an astrophysicist at the University of California, Berkeley, said in the same statement. "No one knows what to make of that so far."

The survey also revealed that half of Andromeda's dwarf galaxies orbit in a unique, flat plane, all moving in the same direction — a configuration not observed around other galaxies, including our own.

"That's weird," Weisz said in the statement. "It was actually a total surprise to find the satellites in that configuration and we still don't fully understand why they appear that way."

The galaxies assembled into the "Great Plane of Andromeda" don't exhibit distinguishable traits, such as patterns in star formation. This suggests the plane is not a physically distinct structure but rather a serendipitous configuration whose origins are not yet fully understood, the researchers say.

"There is a lot of diversity that needs to be explained in the Andromeda satellite system," Weisz said in the statement. "The way things come together matters a lot in understanding this galaxy's history."

Astronomers have discovered an enormous black hole the size of 36 billion suns lurking within the "Cosmic Horseshoe." The behemoth object is one of the largest black holes ever detected.

First discovered in 2007, the Cosmic Horseshoe is a system of two galaxies located in the constellation Leo. Images of the system show a halo of light surrounding the foreground galaxy, LRG 3-757. This phenomenon, known as an Einstein ring, occurs when the significant mass of the galaxy warps and magnifies light from an even more distant galaxy behind it.

This type of magnification is called gravitational lensing and was first predicted by Albert Einstein in 1915. Now, new research has revealed just how LRG 3-757 gets the mass required to bend light: from a monstrous ultramassive black hole sitting in its center. The researchers published their findings Feb. 19 on the preprint server arXiv, so they have not been peer-reviewed yet.

Einstein's theory of general relativity describes the way massive objects warp the fabric of the universe, called space-time. Gravity, Einstein discovered, isn't produced by an unseen force but by space-time curving and distorting in the presence of matter and energy.

This curved space, in turn, sets the rules for how energy and matter move. Even though light travels in a straight line, light traveling through a highly curved region of space-time, such as the area around a massive galaxy, also travels in a curve — bending around the galaxy and splaying out into a halo.

Related: Mysterious 'Green Monster' lurking in James Webb photo of supernova remnant is finally explained

To find evidence for the black hole lurking within the Cosmic Horseshoe, the astronomers used data collected from the Multi Unit Spectroscopic Explorer spectrograph in Chile's Atacama Desert, alongside images gathered by the Hubble Space Telescope.

By analyzing the powerful gravitational lensing by LRG 3-757 — a galaxy with 100 times the mass of the Milky Way — alongside the speed and manner at which stars move around it, the researchers concluded that the presence of an ultramassive black hole "is necessary to fit both datasets simultaneously."

This detection puts LRG 3-757’s black hole among the largest to ever exist. The biggest, called Ton 618, is estimated to weigh in at 66 billion times the mass of our sun and stretch up to 40 times the distance between Neptune and the sun. Meanwhile, the black hole at the centre of the Holm 15A galaxy cluster is 44 billion solar masses and spans up to 30 times the Neptune to sun distance.

An ultramassive mystery

Astronomers haven't yet explored exactly how LRG 3-757's giant black hole formed. But the stars moving around it are relatively slow, and their movements are less random than would be expected for a black hole of its size.

This could be because some of the stars near it were ejected by past galaxy mergers, or because the black hole once had powerful jets that quenched star formation. Or perhaps the black hole quickly gobbled up many of its surrounding stars earlier in its life.

The astronomers expect to find some of the answers to these questions from the Euclid space telescope, which is one year into its six-year mission to catalog a third of the entire night sky by capturing thousands of wide-angle images. All told, Euclid will capture light from more than a billion galaxies that are up to 10 billion years old, according to the European Space Agency.

Once this is done, astronomers will use Euclid's images to create two maps: one composed of many other Einstein rings, and the other showing shock waves called baryon acoustic oscillations. These maps should help researchers trace dark matter and dark energy — mysterious components of the universe believed to make up most of its matter and cause its accelerating expansion, respectively.

"The Euclid mission is expected to discover hundreds of thousands of lenses over the next five years," the authors wrote in the study. "This new era of discovery promises to deepen our understanding of galaxy evolution and the interplay between baryonic [regular matter] and [dark matter] components."

The scientists behind NASA's largest and most powerful space telescope ever built are bracing for potentially crippling budget cuts, and the observatory is only halfway through its primary mission.

The team overseeing NASA's James Webb Space Telescope (JWST) has been directed to prepare for up to 20% in budget cuts that would touch on every aspect of the flagship observatory's operations, which are managed by the Space Telescope Science Institute (STScI) in Maryland. The potential cut comes even as the space observatory is more in demand than ever before, with astronomers requesting the equivalent of nine years' worth of Webb observing time in one operational year.

"NASA is having budget constraints across the entire board, so the institute is being asked to consider a significant — about 20% — cut to our operational budget for the mission starting later this year," Tom Brown, who leads the Webb mission office at STScI, told a crowd of scientists last month at the 245th American Astronomical Society (AAS) meeting in National Harbor, Maryland. "So the impacts of that, if it comes to pass, pretty much cut across the entire mission."

NASA's $25.4 billion budget request for 2025 set aside $317 million to fund the Webb space telescope, as well as the Hubble Space Telescope and Chandra X-ray Observatory that together comprise NASA's currently operational "Great Observatories." The Hubble Telescope program is facing a potential 20% budget cut of its own, according to SpaceNews. And Chandra is facing the end of its mission, with NASA's 2025 budget request including plans to wind down operations, with its budget dropping from $41.1 million this year to just $5.2 million in 2029.

But unlike Hubble, which turns 35 this spring, and Chandra, which launched in 1999, Webb is in its prime, approaching the midpoint of a primary 10-year mission. It could last at least 20 years or more, NASA officials have said. The mission is an international partnership between NASA, the European Space Agency and the Canadian Space Agency.

"Frankly, this mission works far better than, really, most folks expected it to, you know," Brown said during the Webb town hall event on Jan. 15 at the AAS conference. "It's extremely worrisome that, while we're in the middle of the prime mission, we're also maybe looking at significant budget cuts."

The $10 billion Webb space telescope survived a tumultuous development process, one that included cost overruns and technical delays that nearly killed the observatory before it ever flew. Lawmakers with the House Appropriations Committee proposed cancelling the mission in 2011, a decade before Webb's Christmas Day launch in 2021, only to back down after backlash from scientists and influential politicians defending the observatory.

Since its 2021 launch, the Webb space telescope has outmatched even the most optimistic predictions for its performance. Its infrared optics have looked deep into the universe's past, observed distant galaxies and exoplanets, and even peered at our own local solar system planets closer to home.

"In a nutshell, it is truly fulfilling its promise," Macarena Garcia Marin, STScI's Webb project scientist, said during the same town hall event. "Across every field, JWST is truly delivering cutting-edge science."

Some of Webb's budget challenges stem from its operational costs, which were set "idealistically low" in 2011 when the observatory was saved from cancellation. Those costs, coupled with inflation rates that were much higher than expected and less flexibility in NASA's budget, have also contributed, Brown said.

According to a presentation by Brown, a 20% cut to Webb's operational budget would definitely affect how much science the telescope could perform. The impacts would be felt across teams that review proposals for observing targets, data analysis, observatory efficiencies, and anomaly resolution when something goes wrong, not to mention the need to engage with the scientific community and public on Webb's science results.

"It's a huge cut. That's not like kind of trying to nibble away at the edges," Brown told Space.com. "That impacts everything across the board, all the way up to how many modes we're offering to the observers."

Those impacts, Brown said, would likely be felt for the first time in October, when the next fiscal year begins.

Brown's comments at the Webb observatory town hall at AAS came just before the inauguration of President Donald Trump, who in subsequent weeks created the Department of Government Efficiency headed by SpaceX CEO Elon Musk to reduce government spending. DOGE, as it's known, has worked to dismantle some entire agencies, like the U.S. Agency for International Development, which provides aid to other countries during disasters and other emergencies, while also overseeing massive cuts to the federal workforce. Nearly 1,000 NASA jobs could be eliminated, though they appear to have been saved from layoffs earlier this week.

Trump has nominated American billionaire entrepreneur Jared Isaacman, who has flown in orbit twice on private SpaceX missions he financed himself, to serve as the next NASA administrator, though Isaacman has yet to be confirmed. The agency is currently being led by Acting Administrator Janet Petro, former director of the agency's Kennedy Space Center in Florida.

Originally posted on Space.com.

The Hubble Space Telescope has discovered a rare "blue lurker" star that has been feeding on material from its two conjoined siblings.

The fast-spinning star provides a detailed look at the complicated family dynamics of multiple-star systems.

"It's a good mid-evolution snapshot of this system, and maybe it will help us put together a clearer picture of the overall evolution of triple systems," Eric Sandquist, an astronomer at San Diego State University who was not involved in the research, told Live Science.

Although the blue lurker looks like a classic sunlike star, it spins much faster because it's propelled by the joint power of three stars in one. Hence, it's "lurking" among a population of much slower stars. The "blue" part comes from how hotter stars like this one tend to appear bluer.

The lurker is a member of the open cluster M67, also known as the "King Cobra Cluster." This 4 billion-year-old group of 500 stars, located 2,800 light-years away, is loosely bound by gravity. Because all of these stars are the same age, they generally spin at about the same rate — except for a sprinkling of curiously speedy stars.

"A typical star in the cluster is rotating around once every 25 days," Emily Leiner, an astronomer at the Illinois Institute of Technology, said at a Jan. 13 news conference at the 245th American Astronomical Society meeting in National Harbor, Maryland. “That's comparable to our own sun… [The blue lurkers] were whipping around every few days."

So Leiner and her team pointed Hubble at one of these lurkers to investigate what could explain its peculiarities. They found that it was accompanied by a white dwarf, the burned-out core of a dead star. But this stellar corpse was so massive that it couldn't have possibly been the remains of only one star.

These observations tell the story of a tricky triplet relationship: The lurker started by orbiting two binary stars locked in a do-si-do of sorts. Eventually, the binary stars merged to create a massive star, which swelled later in life. The lurker then siphoned material from the inflated star, which caused the lurker to spin faster and faster as the white dwarf met its demise.

"It's not rare for stars to go through this mass-transfer process; what's harder is finding them," Leiner told Live Science. About 10% of stars fall within triple-star systems like this one, she said, but it's not often that astronomers can trace their evolutionary pathways quite so clearly. Whereas the life cycle of a single star can be predicted easily through modeling, multiple-star systems come with more complexities and thus require detailed observations to begin unraveling their history.

Sandquist is interested in seeing how prevalent blue lurkers are and whether they are tied to other cosmic phenomena, like Type Ia supernovas — a landmark type of explosion used to measure the universe's expansion rate. If lurkers like these turn out to be a common culprit behind Type Ia supernovae, they won't just help us understand triple-star systems but could also shed light on the universe’s evolution.

The Hubble Space Telescope has finally completed a stunning mosaic of the Milky Way's closest cosmic companion, the Andromeda Galaxy — having spent more than a decade snapping the spectacular image.

The new image, which was released Jan. 16 by the European Space Agency (ESA), is made up of approximately 600 different fields of view and shows the spiral galaxy "almost edge-on," or tilted 77 degrees compared to how we normally see it from Earth.

To do this, researchers ran two different observing programs to independently capture the northern and southern halves of the galaxy. It "was a herculean task" that required Hubble to orbit Earth more than 1,000 times, ESA representatives wrote in the statement.

The mosaic contains roughly 2.5 billion individual pixels — a new record for an image of Andromeda. This unprecedented level of detail has enabled researchers to resolve more than 200 million stars in the image, which start to "look like grains of sand across the beach" as you zoom in on different parts of the image, according to the statement.

"But that’s just the tip of the iceberg," the ESA representatives added. In total, scientists estimate that Andromeda could have as many as 1 trillion stars, which is up to 10 times more than the Milky Way, according to ESA.

Related: The Milky Way could be part of a much larger 'cosmic neighborhood' than we realized, challenging our understanding of the universe

The new image will enable scientists to better understand Andromeda's past. Astronomers believe the galaxy once collided with one of its current satellite galaxies, Messier 32, and likely stole most of the latter's stars in the process. This means that comparing the distribution of the different stars within Andromeda can tell us more about this cosmic collision.

Any potential findings could also shed light on the Milky Way's future because our galaxy is predicted to potentially collide with Andromeda in the next 5 to 10 billion years.

Hubble and Andromeda

The release of the new Hubble image coincides with the 100th anniversary of the discovery of Andromeda by the spacecraft's namesake, Edwin Hubble, according to Live Science's sister site Space.com.

Prior to that 1915 discovery, scientists believed that all the stars in the night sky belonged to a single galaxy, and they had no concept of the scale of the wider universe. But in the century since, telescopes like Hubble have helped to show us that there are more than 100 billion galaxies within the entire cosmos.

However, at a distance of around 2.5 million light-years from Earth, which is comparatively tiny on a cosmic scale, Andromeda is the most easily accessible galaxy to us — and has helped us learn a great deal about our own galaxy.

"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," the ESA representatives wrote.

What it is: Spiral galaxy UGC 10043

Where it is: 150 million light-years away in the constellation Serpens

When it was shared: December 12, 2024

Why it's so special: This image of a spiral galaxy taken by the Hubble Space Telescope is a portrait more than two decades in the making.

Like most full-color images of space objects, it's a composite of images taken in different wavelengths of light. What sets this image apart, however, is that the data used to create it was collected during observation sessions in 2000 and 2023 — 23 years apart. That's one advantage of having a space telescope in orbit for so long: Hubble was launched from the space shuttle Discovery on April 24, 1990, and its long service has enabled it to capture a huge amount of data about every corner of the cosmos.

But besides the prolonged methods used to create it, it's also an unusual image on its face. Spiral galaxies — which account for about 60% of all galaxies in the universe, according to the European Space Agency — are, by chance, typically seen face-on when viewed from the solar system. That’s why spiral galaxies are typically associated with vivid spiral arms, which can only be seen from a face-on vantage. However, UGC 10043 is viewed edge-on, with its rings seemingly flattened into a line. This unique angle gives astronomers the chance to see how spiral galaxies are structured in 3D.

Related: Space photo of the week: Hubble celebrates 10 years of hunting giants

This image of UGC 10043 reveals obvious lanes of dust, which would likely look like spiral arms if the galaxy was seen face-on. Here, they appear to block the collective glow of the stars that make up the galaxy itself. They also contain dark clouds, which are star-forming regions.

At the center of the image is a bulge of light — the galaxy's bright core. All galaxies have one, but UGC 10043's is unusually large. Astronomers think it may be because UGC 10043 has collided with a dwarf galaxy nearby, leaving it with extra dust and gas that has fueled it to create new stars. A collision could also explain why the galaxy's disk is slightly warped, bending up at one end and down at the other.

For more sublime space images, check out our Space Photo of the Week archives.

Astronomers have spotted one of the most powerful shock waves ever seen, caused by a galaxy slamming into four of its neighbors while traveling at 2 million mph (3.2 million km/h).

The cosmos-rattling event occurred in Stephan's Quintet, when one of the system's five galaxies, called NGC 7318b, smashed into the other four.

NGC 7318b's entry into the system created an immensely powerful shock front akin to a "sonic boom from a jet fighter," the researchers said. They hope that by studying it they can understand more about the violent and chaotic interactions between galaxies. They published their findings Nov. 22 in the journal Monthly Notices of the Royal Astronomical Society.

"It's basically a huge intergalactic field of debris," Marina Arnaudova, an astrophysicist at the University of Hertfordshire in the U.K., told Live Science. "The new intruder NGC7318b has smashed into the debris field, and compressed the plasma and gas in it. In doing so it has re-energised the plasma causing it to glow brightly at radio frequencies, and likely triggered star formation in the process."

Named after French astronomer Édouard Stephan, who discovered it in the 19th century, Stephan's Quintet is a group of five galaxies that are "locked in a cosmic dance of repeated close encounters," according to NASA.

Related: James Webb Space Telescope discovers mysterious 'red monster' galaxies so large they shouldn't exist

The quintet sits around 290 million light-years from Earth and was the first compact galaxy group ever spotted. It has been imaged by numerous telescopes, including the Hubble Space Telescope and the James Webb Space Telescope.

To investigate the quintet's behavior and cosmic history, the researchers behind the new study used the William Herschel Telescope Enhanced Area Velocity Explorer (WEAVE), a spectrograph mounted to the William Herschel Telescope on the island of La Palma.

By breaking light from the system down into its constituent parts, the WEAVE spectrograph tracked the debris remnants, the births of new stars and the trails of ionized gas left behind by the force of the collision. All of these elements were stirred up by the shock front, which rippled out at hypersonic speeds following NGC 7318b's entry into the system.

Astronomers studying Stephan's Quintet could gain valuable insights into how collisions and mergers stretching back to the Big Bang shaped the galaxies we see today, and what the system may look like in the future, the researchers said.

"This type of galaxy collision in Stephan's Quintet is a rare chance to see a complex set of galaxies caught in the act of colliding," Arnaudova said. "As to how it will end up, well it's likely that it will eventually merge with one of the group members, but not for millions or billions of years because the sizes and speeds of these things are so vast."

The observations are the first to be made by WEAVE, but far from the last. The researchers say the spectrograph will also be used to study the reionization of the universe in the aftermath of the Big Bang; cast new light on how stars form and accrete over time; and perform a number of "galactic archaeology" experiments to find how our own Milky Way grew over cosmic time.

Astronomers have scoured decades-old data from NASA's Chandra X-ray Observatory, finding bright, lumpy features dotting a jet of energy spit out by a nearby black hole. Puzzlingly, the "knots" clock a faster speed when seen in X-rays than they do in radio wavelengths. scientists said.

"The X-ray data traces a unique picture that you can't see in any other wavelength," study lead author David Bogensberger, an astrophysicist at the University of Michigan, who led the new study, said in a recent news release. "We've shown a new approach to studying jets and I think there's a lot of interesting work to be done."

The study, which was published Oct. 18 in The Astrophysical Journal, comes as NASA delays its final decision about budget cuts that would determine the fate of the observatory (which faces premature cancellation after its budget was slashed due to the agency's financial restrictions) and of the X-ray community that relies on it for research. NASA continues to operate on 2024 levels despite a new fiscal year having kicked in Oct. 1, partly due to its 2025 budget being dependent on the outcome of the presidential election and changes in party in the House and Senate, SpaceNews reported.

Meanwhile, astronomers continue to stress the science value being delivered by the X-ray telescope, which turned 25 years old in July.

In the new study, Bogensberger and his team analyzed two decades of Chandra's observations of the active supermassive black hole lurking at the heart of Centaurus A galaxy, a somewhat misshapen elliptical swirl of gas and dust roughly 12 million light-years from Earth. At least one of the newfound "jet knots" appears to be traveling at 94% the speed of light, which was higher than the 80% of light's speed clocked in radio observations, according to the paper.

Related: James Webb and Chandra telescopes spot a 'lighthouse' pointed at Earth

"What this means is that radio and X-ray jet knots move differently," Bogensberger said in the statement. "There's a lot we still don't really know about how jets work in the X-ray band."

The Centaurus A galaxy was discovered as early as the mid-1800s, but it wasn't until a century later that its twin jets came into view of then-new radio telescopes. One of the jet's northeastern side points toward Earth, while the other, called the counterjet, faces southwest and is significantly fainter, according to the study.

Astronomers know that black hole jets are fueled by material swept up by the cosmic behemoths and expelled before it can reach the event horizon, which is the boundary around black holes that traps everything, including light, for eternity. However, precisely how the material is funneled to the jet is poorly understood; prevailing theory suggests powerful, messy magnetic fields around the black hole and the behemoth's spin itself may be important contributors.

In addition to how the observed knots may have formed, researchers are also puzzled over their changing brightness. During the two decades, from 2002 to 2022, a knot became brighter while another faded. Back in 2009 astronomers spotted the same trend in jet knots blasted by a monster black hole in the center of M87 galaxy, which resides roughly 55 million light-years from Earth in the constellation Virgo. For reasons unknown, those knots brightened over several years to the point that they outshined even the galaxy's brilliant core before fading into the darkness of space.

Forthcoming investigations into the jets of Centaurus A and other galaxies could reveal whether the knot's varied speeds and brightness is an intrinsic behavior of the jet as it blasts away from the black hole, or an external obstacle, such as interstellar material.

"A key to understanding what's going on in the jet could be understanding how different wavelength bands trace different parts of the environment," Bogensberger said in the statement. "Now we have that possibility."

Originally posted on Space.com.

What it is: The spiral galaxy IC 3225

Where it is: 100 million light-years away, in the constellation Virgo

When it was shared: Oct. 21, 2024

Why it's so special: The spiral galaxy IC 3225 looks like it's going somewhere. At first glance, it may seem like any other large spiral galaxy, such as our Milky Way, with its bright, glowing center and faint dust scattered throughout. But all is not well in IC 3225. On one side is a spiral arm dense with new blue stars; on the other is a more diffuse, starless and generally chaotic region that looks like a tail.

According to NASA, which recently shared this Hubble Space Telescope image, IC 3225 looks like it's been launched from a cannon, speeding through space like a comet with a tail of gas streaming behind it. So what happened to IC 3225?

A galaxy may be an island of stars, but they don't exist alone; galaxies are almost always found in groups, which can contain thousands of "islands" held together by gravity.

IC 3225 is one of more than 1,300 galaxies that make up the Virgo Cluster. It's a collection of gravitationally bound galaxies centered in the constellation Virgo.

The concentration of galaxies in the Virgo Cluster is so dense that a rich field of hot gas flows between them as something astronomers call the "intracluster medium," according to Swinburne University. The trouble is, there's so much mass in the Virgo Cluster that galaxies orbit its center very quickly, "ramming" through the intracluster medium. That creates "ram pressure" inside the galaxies, which strips out their gas as they travel. At some point, that happened to IC 3225, which astronomers think has since moved away from the cluster's core.

The debris is clear, with a leading edge of the star-forming region and a somewhat stretched-looking back end. According to NASA, another explanation for the chaos is that IC 3225 was deformed when it passed too close to another galaxy and the gravitational forces stretched it out.

Remarkably, the Virgo Cluster and its 1,300 galaxies have more than 100 other groups of galaxies orbiting it. Together, they are known as the Virgo Supercluster (or Local Supercluster) of galaxy groups, which stretches 100 million light-years across. In turn, the Virgo Supercluster is part of a larger structure of galaxy clusters called Laniakea, Hawaiian for "immense heaven." It contains about 100,000 galaxies, according to Space.com.

For more sublime space images, check out our Space Photo of the Week archives.

The venerable Hubble Space Telescope has watched Jupiter's Great Red Spot (GRS) oscillating, as though it were being squeezed in and out roughly every 90 days.

Why this huge anticyclone, which has been shrinking over the decades and currently measures about 9,165 miles (14,750 kilometers) across (although astrophotographer Damian Peach has reportedly measured it to be just 7,770 miles, or 12,500 km, wide), is behaving in such fashion is a mystery.

"With Hubble's high resolution, we can say that the GRS is definitely squeezing in and out at the same time as it moves faster and slower," said Amy Simon, of NASA's Goddard Space Flight Center in Maryland, in a statement. "This was very unexpected, and at present there are no hydrodynamic explanations."

Astronomers led by Simon used Hubble to observe the Great Red Spot for 88.5 days between December 2023 and March 2024. A timelapse of images taken during that period shows that the GRS periodically expands and shrinks along its semi-major axis (the widest part of an ellipse).

"While we know its motion varies slightly in longitude, we didn't expect to see the size oscillate as well," said Simon.

Related: Jupiter's Great Red Spot is 40 times deeper than Mariana Trench

Located 22 degrees south of Jupiter's equator, positioned on the edge of the Jovian atmosphere's South Equatorial Belt, the GRS is buffeted from above and below by mighty jet streams that whip around the giant planet at 266 mph 428 kph. The jet streams stop the huge vortex from wandering into other latitudes, although it is seen to drift westward with respect to the rest of the atmosphere. This drift isn't constant, but it has been measured to accelerate and decelerate over an approximately 90-day oscillation.

"As it accelerates and decelerates, the GRS is pushing against the windy jet streams to the north and south of it," said Mike Wong of the University of California, Berkeley.

Seemingly connected to this approximately 90-day oscillation in its westward drift is the squeezing of the GRS' shape seen by Hubble.

"It's similar to a sandwich where the slices of bread are forced to bulge out when there's too much filling in the middle," said Wong.

The degree of squeezing seems to be anti-correlated with the rate at which the GRS is drifting. During the periods when the GRS' drift has decelerated, the width of the vortex and the size of its core are at their greatest. The core also shines brighter in ultraviolet light when it is at its largest, indicative of there being less haze absorption in the atmosphere above it. When the drift accelerates, the width of the GRS and the size of its core contracts. This may be the result of the GRS interacting with the surrounding atmosphere when its drift rate speeds up.

So far, only one oscillatory period has been observed in full by Hubble. Simon leads the Outer Planet Atmospheres Legacy (OPAL) program, which uses Hubble to image each of the four giant planets in the outer solar system — Jupiter, Saturn, Uranus and Neptune — at least once per year. However, Hubble's studies of the GRS were a separate project in addition to that.

A group of top amateur astronomers, such as Damian Peach, also routinely image Jupiter in high resolution, and their data is so good that Simon and the OPAL team often work with them. It's possible that this squeezing of the spot is evident in amateur images, although Simon thinks it might be slightly too subtle for amateur data to have captured it with any reliability, with the width of the spot varying by just 0.3 degrees in longitude over a two-week period. Nevertheless, now that we know it is occurring, amateurs may be able to finesse their image capture in order to spot it.

Simon also wants to take another look at the GRS with the James Webb Space Telescope, which previously imaged the Jovian storm in near-infrared light earlier this year and found atmospheric waves above the GRS. By being able to probe deeper into the GRS at longer mid-infrared wavelengths, Simon hopes to see whether wind velocities within the storm are also changing in time with the oscillations.

The overall shrinking of the GRS, now coupled with the oscillatory squeezing, mean that the storm is undergoing some interesting changes. Where will it end?

"Right now, it's over-filling its latitude band relative to the wind field," said Simon. "Once it shrinks inside that band, the winds will really be holding it in place." When this happens, it may stabilize in size, but for now that remains speculation until more data can be gathered.

The discovery was reported on Oct. 9 in a paper published in The Planetary Science Journal.

Originally posted on Space.com.

Supermassive black holes are some of the most impressive (and scary) objects in the universe — with masses around one billion times more than that of the Sun. And we know they've been around for a long time.

In fact, astronomers have detected the extremely luminous compact sources that are located at the centres of galaxies, known as quasars (rapidly growing supermassive black holes), when the universe was less than 1 billion years old.

Now our new study, published in Astrophysical Journal Letters, has used observations from the Hubble Space Telescope to show that there were many more (much less luminous) black holes in the early universe than previous estimates had suggested. Excitingly, this can help us understand how they formed — and why many of them appear to be more massive than expected.

Black holes grow by swallowing up material that surrounds them, in a process known as accretion. This produces tremendous amounts of radiation. The pressure from this radiation places a fundamental limit on how quickly black holes can grow.

Scientists were therefore faced with a challenge in explaining these early, massive quasars: without much cosmic time in which to feed, they must have either grown quicker than physically possible, or been born surprisingly massive.

Related: A 'primordial' black hole may zoom through our solar system every decade

Light vs. heavy seeds

But how do black holes form at all? Several possibilities exist. The first is that so-called primordial black holes have been in existence since shortly after the big bang. While plausible for black holes with low masses, massive black holes cannot have formed in significant numbers according to the standard model of cosmology.

Black holes definitely can form (now verified by gravitational wave astronomy) in the final stages of the short lives of some normal massive stars. Such black holes could in principle grow quickly if formed in extremely dense star clusters where stars and black holes may merge. It is these "stellar mass seeds" of black holes that would need to grow up too fast.

The alternative is that they could form from "heavy seeds", with masses around 1,000 times greater than known massive stars. One such mechanism is a "direct collapse", in which early structures of the unknown, invisible substance known as dark matter confined gas clouds, while background radiation prevented them from forming stars. Instead, they collapsed into black holes.

The trouble is that only a minority of dark matter halos grow large enough to form such seeds. So this only works as an explanation if the early black holes are rare enough.

Too many black holes

For years, we have had a good picture of how many galaxies existed in the first billion years of cosmic time. But finding black holes in these environments was extremely challenging (only luminous quasars could be proven).

Although black holes grow by swallowing surrounding material, this does not happen at a constant rate — they break their feeding into "meals", which makes their brightness vary over time. We monitored some of the earliest galaxies for changes in brightness over a 15 year period, and used this to make a new census of how many black holes are out there.

It turns out that there are several times as many black holes residing in ordinary early galaxies than we originally thought.

Other recent, pioneering work with the James Webb Space Telescope (JWST) has begun to reach similar conclusions. In total we have more black holes than can form by direct collapse.

There is another, more exotic, way of forming black holes that could produce seeds that are both massive and abundant. Stars form by gravitational contraction of gas clouds: if significant numbers of dark matter particles can be captured during the contraction phase, then the internal structure could be entirely modified — and nuclear ignition prevented.

Growth could therefore continue for many times longer than the typical lifetime of an ordinary star, allowing them to become much more massive. However, like the ordinary stars and direct collapse objects, nothing is ultimately able to withstand the overpowering force of gravity. This means these "dark stars" should also eventually collapse to form massive black holes.

We now believe that processes similar to this should have taken place to form the large numbers of black holes we observe in the infant universe.

Future plans

Studies of early black hole formation have undergone a transformation in the last two years, but in a sense this field is only just beginning.

New observatories in space, such as the Euclid mission or the Nancy Grace Roman Space Telescope, will fill in our census of fainter quasars at early times. The NewAthena mission and the Square Kilometer Array, in Australia and South Africa, will unlock our understanding of many of the processes surrounding black holes at early times.

But it is really the JWST that we must watch in the immediate term. With its sensitivity for imaging and monitoring and spectroscopic capabilities to see very faint black hole activity, we expect the next five years to really nail down black hole numbers as the first galaxies were forming.

We may even catch black hole formation in the act, by witnessing the explosions associated with the collapse of the first pristine stars. Models say this is possible, but it will demand a coordinated and dedicated effort by astronomers.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

Astronomers using the Hubble Space Telescope have discovered a gigantic "blowtorch-like" jet blasting out of a black hole — and it seems to be causing nearby stars to explode.

The 3,000-light-year-long trail of flaming plasma is beaming out from a supermassive black hole with a mass 6.5 billion times that of the sun in the center of the galaxy M87.

Getting caught in this beam would be deadly for any cosmic object, but according to new observations, even being in its vicinity can be devastating. The superheated energy beam appears to be causing nearby star systems to erupt in explosions called novas. Yet exactly why this is happening remains a mystery.

"We don't know what's going on, but it's just a very exciting finding," study lead author Alec Lessing, an astrophysicist at Stanford University, said in a NASA statement. "This means there's something missing from our understanding of how black hole jets interact with their surroundings."

The researchers published their findings Aug. 14 on the pre-print server arXiv, so it has yet to be peer-reviewed.

Related: Biggest black hole jets ever seen are as long as 140 Milky Ways

Supermassive black holes typically sit at the centers of galaxies, sucking in matter from their surroundings before spitting it out at extreme speeds, thus creating a feedback process that shapes how galaxies evolve. As material approaches a black hole's "mouth," friction causes it to heat up and emit light trillions of times more luminous than the brightest stars that can be detected by telescopes. Occasionally, active black holes funnel this infalling matter into gargantuan energy jets that spew into space, sometimes spanning entire galaxies.

However, how these jets affect their surroundings is largely unknown. By pointing Hubble near the M87 jet, the researchers found that twice as many novas were erupting in star systems near the jet than in the wider galaxy.

Novas typically occur in binary star systems after a white dwarf — the smoldering husk of a dead star — steals hydrogen fuel from its normal star partner, causing the white dwarf to explode like a giant nuclear bomb. It seems the black hole jet is causing the same thing to happen to these nova systems, but the exact mechanism has not been observed.

"There's something that the jet is doing to the star systems that wander into the surrounding neighborhood," Lessing said. "Maybe the jet somehow snowplows hydrogen fuel onto the white dwarfs, causing them to erupt more frequently.

"But it's not clear that it's a physical pushing," he added. "It could be the effect of the pressure of the light emanating from the jet. When you deliver hydrogen faster, you get eruptions faster. Something might be doubling the mass transfer rate onto the white dwarfs near the jet."

Another possibility, the researchers said, is that the jet material was somehow being captured by the regular companion stars, causing them to spill onto their white dwarf counterparts.

To find the answers, astronomers will need to look for direct observations of star eruptions occurring around cosmic jets. This is far from easy, but given that one nova erupts in M87 every day, it isn't impossible.

The rosy red structures of a nearby galaxy glow brightly in a new image from the Hubble Space Telescope.

The Andromeda Galaxy — the Milky Way's closest galactic neighbor — is located about 2.5 million light-years away. Measuring approximately 152,000 light-years across, it has nearly the same mass as our Milky Way galaxy. A recent hubble image, released on Aug. 30, captures a detailed view of the northeast region of the famed galaxy, including its intricately woven spiral arms and swathes of ionized gas that fuel star formation.

Related: Space photo of the week: The 1st image of an alien planet

"The combination of stellar nurseries and supernovas create a dynamic environment that excites the surrounding hydrogen gas, flourishing it into a garden of star-studded roses," NASA officials said in a statement.

Using Hubble's Advanced Camera for Surveys and Wide Field Camera 3, researchers were able to peer through the clouds of gas and hone in on Andromeda's spiral arms to analyze the galaxy's vast collection of stars.

"The extent of the study spanned a vast range of stars, providing not just a clear view of Andromeda's stellar history and diversity, but also more insight on stellar formation and evolution overall," NASA officials said in the statement.

"By examining these stars in our local cosmic neighborhood, scientists can better understand those within galaxies in the distant universe."

Andromeda is believed to be falling toward the Milky Way due to gravitational forces between the two galaxies and the invisible dark matter that surrounds them both. Ultimately, the two galaxies are expected to experience a head-on collision in about 2 billion to 4 billion years, which will drastically alter the structure of both Andromeda and the Milky Way as we know them today. However, some new research casts doubt on this collision theory — so, perhaps only time will tell.

Originally posted on Space.com.

A nearby galaxy is shining with star formation in a new image from the Hubble Space Telescope.

The spiral galaxy Messier 33 (M33), also known as the Triangulum Galaxy, is the third-largest member of the Local Group of galaxies, after the Andromeda galaxy (M31) and our own Milky Way. Measuring only 60,000 light-years across, M33 is about half the size of the Milky Way.

Located nearly 3 million light years from Earth, the Triangulum Galaxy is regarded as a "hotbed of starbirth," forming stars at a rate 10 times higher than the neighboring Andromeda galaxy, according to a statement from NASA.

"Interestingly, M33's neat, organized spiral arms indicate little interaction with other galaxies, so its rapid starbirth is not fueled by galactic collision, as in many other galaxies," NASA officials said in the statement.

Instead, new stars are born from ample amounts of dust and gas within the galaxy. Collisions between massive ionized hydrogen clouds, known as H-II regions, create high-mass stars, which can be seen in the new Hubble image. The large reddish clouds in the Hubble photo represent the pockets of ionized hydrogen, which, along with the dark streams of gas, fuel the galaxy's rapid star formation.

Related: Hubble tracks farthest and most powerful fast radio burst back to 'blob' of 7 galaxies

"The apparent graininess of the image is actually swarms of countless stars," NASA officials said in the statement. "M33 is one of less than 100 galaxies close enough for telescopes like Hubble to resolve individual stars, as evident here."

However, unlike most spiral galaxies, M33 lacks a central bulge, which would otherwise house a supermassive black hole. As a result, M33 is classified as a "pure disk galaxy," which is a type of galaxy that is believed to make up around 15-18% of all galaxies in the universe.

The new Hubble image, released on Aug. 21, was taken as part of a larger study on the interstellar medium, star-formation processes and stellar evolution, which scientists hope will offer insight on the possible future collision between M33 and the Andromeda and Milky Way galaxies.

Originally posted on Space.com.

What it is: Globular cluster NGC 2005

Where it is: 162,000 light-years away, in the Large Magellanic Cloud, a satellite galaxy of the Milky Way, and visible in the constellation Dorado

When it was shared: July 7, 2024

Why it's so special: This new image from the Hubble Space Telescope shows an object with mysterious origins that's commonly seen in the Milky Way: a globular cluster, a densely packed and gravitationally bound group of tens of thousands or millions of stars. However, NGC 2005 is actually located in the Large Magellanic Cloud (LMC), a dwarf galaxy close to the Milky Way, and can be easily seen at night from the Southern Hemisphere. 

Globular clusters are thought to be billions of years old. About 150 are known to exist in the halo of the Milky Way. They orbit its center in the opposite direction as most other objects in our galaxy, providing evidence for a theory that they were captured while the Milky Way was merging with other galaxies, according to NASA. That's how astronomers think galaxies evolve and grow. Another clue is that globular clusters host some of the oldest stars in the universe.

Related: The Milky Way will be visible without a telescope this summer. Here are the key nights to watch for.

NGC 2005 is the perfect test case because it exists outside the Milky Way but is close enough to be studied carefully. It's about 750 light-years from the heart of the LMC, the biggest of about 40 dwarf galaxies near the Milky Way. Many of these dwarf galaxies are thought to orbit the Milky Way, though recent data from the Gaia spacecraft suggest that many of them may just be passing by. 

If galaxies evolve by merging with others, there ought to be ancient stars in all galaxies whose chemical compositions differ from those around them. That's exactly the case with NGC 2005. It appears to be a relic — possibly the core — of a dwarf galaxy that has long since been consumed. 

The LMC can be easily seen from the Southern Hemisphere on almost any clear night with a good small telescope or a pair of stargazing binoculars. The LMC is 162,000 light-years from the solar system, making it one of the closest galaxies to the Milky Way. It contains globular clusters, dense star fields and the Tarantula Nebula, a supermassive version of the Milky Way's Orion Nebula. 

What it is: A 3D visualization of the "Pillars of Creation," an iconic image of interstellar gas and dust taken by the Hubble Space Telescope in 1995. 

Where it is: The Eagle Nebula (M16), about 6,000 light-years away, in the constellation Serpens

When it was shared: June 26, 2024

Why it's so special: The "Pillars of Creation" might just be the most famous deep-sky image ever taken. Featuring towering tendrils of interstellar gas and dust in a star-forming region called the Eagle Nebula, it was one of the Hubble Space Telescope's first images and has become a staple of space merchandise and even appeared on a postage stamp. 

Now, the jaw-dropping image has had a multiwavelength 3D makeover thanks to new data from the James Webb Space Telescope (JWST).

This new mosaic, which is also showcased in a new NASA video, highlights the differences between the two telescopes. JWST's newer data isn't necessarily better; it merely helps astronomers study different aspects of the same object. Space telescopes typically specialize in certain wavelengths of light. While Hubble captures primarily visible light, JWST is more sensitive to infrared light.

"When we combine observations from NASA's space telescopes across different wavelengths of light, we broaden our understanding of the universe," Mark Clampin, Astrophysics Division director at NASA Headquarters in Washington, D.C., said in a statement. "The Pillars of Creation region continues to offer us new insights that hone our understanding of how stars form. Now, with this new visualization, everyone can experience this rich, captivating landscape in a new way."

Related: 35 jaw-dropping James Webb Space Telescope images

The nebula's pillars — vast fingers of cool molecular hydrogen and dust — shown in the image are being slowly eroded by the ultraviolet light from hot, young stars being born in the region, though just out of shot. 

Hubble's visible-light data can be seen as impenetrable, brown dust and yellow, ionized gas with a greenish-blue background. The new infrared data from JWST makes the pillars seem semi-transparent, with light-blue ionized gas set against a dark-blue background. Infrared light penetrates all but the densest parts of the pillars of gas and dust. The tallest pillar is about 3 light-years across.

This is not the first infrared makeover of the "Pillars of Creation." In 2015, to celebrate its 25th anniversary, Hubble imaged the Eagle Nebula in near-infrared light for the first time. Meanwhile, JWST released its first image of the iconic Pillars in 2022.

What it is: NGC 1546, a spiral galaxy

Where it is: 50 million light-years away, in the Southern Hemisphere constellation Dorado 

When it was shared: June 18, 2024

Why it's so special: This is the first image from the Hubble Space Telescope in its new pointing mode. The iconic observatory's science operations were suspended in late May after technical issues with one of its gyroscopes — devices that contain spinning wheels to help the telescope manage its movement. This component accurately points the telescope and measures the speed at which an object turns, according to the Hubble website. By June 14, engineers had decided to allow the aging space telescope to operate using just one gyroscope.

It's not a perfect solution. Hubble needs three gyroscopes to operate properly, and using one limits what it can point at — but this early evidence shows that the telescope can still get exquisite images.

Now, this image of the galaxy NGC 1546 is the first fruit of Hubble's new operating mode, although it used some data from the James Webb Space Telescope and the Atacama Large Millimeter/submillimeter Array in Chile to fill in certain details.

Related: Space photo of the week: NASA sees a 'Platypus' move on Jupiter's moon Europa

The resulting multiwavelength image of NGC 1546 shows its bright core, dust lanes and regions where stars are born. From Hubble's point of view, the dust lanes are backlit by the galaxy's bright core, which gives them a rusty-brown look. The core is yellowish, which suggests that older stars dominate it. The bluish light visible within the dust are regions of young stars being born. 

The image, about 39,000 light-years across, also features background galaxies, including an edge-on spiral galaxy on the left side of NGC 1546. The photo was taken using Hubble's Wide Field Camera 3. 

Hubble's six gyroscopes were replaced in 2009 by astronauts visiting on a space shuttle. Each gyroscope contains a wheel spinning at 19,200 revolutions per minute. According to NASA, Hubble now has just two working gyroscopes remaining — one is in use, and one is in reserve. The space agency says this will allow Hubble to continue making observations for many more years.

What it is: NGC 4753, a lenticular galaxy

Where it is: 60 million light-years from Earth in the constellation Virgo

When it was shared: May 13, 2024

Why it's so special: This is the best-ever image of NGC 4753, a galaxy with uniquely distorted dust lanes that have led some people to nickname it the "train-wreck galaxy." 

This new image from the Hubble Space Telescope, published hot on the heels of a similar image taken using the Gemini South telescope in January, shows NGC 4753 in more detail than ever before. A bright white core sits at the center of the image, with dark-brown dust lanes creating an almost web-like tunnel or tent around its nucleus. 

NGC 4753 is a lenticular galaxy — a cross between a spiral galaxy like the Milky Way and an elliptical galaxy, according to NASA. Lenticular galaxies have a central bulge and disk — just like a spiral galaxy — but they appear to lack spiral arms teeming with stars. Instead, like elliptical galaxies, they have stars orbiting in a featureless pattern. Those scattered stars are often older, with few new stars being born. 

Related: Some of the oldest stars in the universe found hiding near the Milky Way's edge — and they may not be alone

Scientists have suggested that NGC 4753's unique look could simply be thanks to our view of it; if viewed directly from above, it may look identical to a spiral galaxy, according to the National Science Foundation.

It's thought that NGC 4753 merged with a dwarf galaxy about 1.3 billion years ago, which could explain where the dust lanes around its nucleus came from. 

NGC 4753 was first discovered by astronomer William Herschel in 1784, and it has since been the location of two known supernova explosions. Both of those explosions were very rare Type Ia supernovas, which are when binary star systems consisting of a white dwarf star (the compact remnant of a sun-like star) and a larger companion star explode. Because these kinds of supernovas shine at exactly the same intrinsic brightness, astronomers use them to measure distance in the universe. They can even be used to measure how fast the universe is expanding.

What it is: The Little Dumbbell Nebula (also known as Messier 76, M76, NGC 650/651, the Cork Nebula and the Barbell Nebula), a planetary nebula

Where it is: 3,400 light-years away, in the constellation Perseus

When it was shared: April 23, 2024

Why it's so special: This is a new image of the Little Dumbbell Nebula (M76), a planetary nebula that's a popular target for telescopes in summer in the Northern Hemisphere.

Issued to mark the 34th anniversary of the Hubble Space Telescope's launch, which occurred on April 24, 1990, the image comes from the newest data in an archive of 184 terabytes stored at the Space Telescope Science Institute in Baltimore.

The Little Dumbbell Nebula is a planetary nebula, which, contrary to what the name suggests, is not the remains of a planet. Rather, it's an expanding shell of gas and dust ejected from a red giant star as it collapsed into a dense, hot white dwarf star. (The shell’s bright, round shape may have been reminiscent of a planet when viewed through early telescopes.)

Related: Speck of light spotted by Hubble is one of the most enormous galaxies in the early universe, James Webb telescope reveals

Hubble's new image shows the Little Dumbbell Nebula as two lobes of glowing gas and dust on both sides of a central bar. Scientists think the rings were caused by a second star that the central white dwarf star has since consumed.

That white dwarf is a special case. At 216,000 degrees Fahrenheit (120,000 degrees Celsius) — 24 times hotter than the sun's surface — it's one of the hottest white dwarf remnants known, European Space Agency representatives wrote in a statement. It's visible as a pinprick of light in the nebula's center.

The rest of the colorful nebula comprises the dust and gas ejected by the central star  at 2 million mph (3.2 million km/h). It's glowing because of ultraviolet radiation from the star, with red denoting nitrogen and blue showing oxygen.

The Little Dumbbell Nebula will be visible for about 15,000 more years before the last of its gas vanishes into space, according to the statement.

Astronomers have used the James Webb and Hubble space telescopes to confirm one of the most troubling conundrums in all of physics — that the universe appears to be expanding at bafflingly different speeds depending on where we look.

This problem, known as the Hubble Tension, has the potential to alter or even upend cosmology altogether. In 2019, measurements by the Hubble Space Telescope confirmed the puzzle was real; in 2023, even more precise measurements from the James Webb Space Telescope (JWST) cemented the discrepancy.

Now, a triple-check by both telescopes working together appears to have put the possibility of any measurement error to bed for good. The study, published February 6 in the Astrophysical Journal Letters, suggests that there may be something seriously wrong with our understanding of the universe.

Related: After 2 years in space, the James Webb telescope has broken cosmology. Can it be fixed?

"With measurement errors negated, what remains is the real and exciting possibility we have misunderstood the universe," lead study author Adam Riess, professor of physics and astronomy at Johns Hopkins University, said in a statement.

Reiss, Saul Perlmutter and Brian P. Schmidt won the 2011 Nobel Prize in physics for their 1998 discovery of dark energy, the mysterious force behind the universe's accelerating expansion.

Currently, there are two "gold-standard" methods for figuring out the Hubble constant, a value that describes the expansion rate of the universe. The first involves poring over tiny fluctuations in the cosmic microwave background (CMB) — an ancient relic of the universe's first light produced just 380,000 years after the Big Bang.

Between 2009 and 2013, astronomers mapped out this microwave fuzz using the European Space Agency's Planck satellite to infer a Hubble constant of roughly 46,200 mph per million light-years, or roughly 67 kilometers per second per megaparsec (km/s/Mpc).

The second method uses pulsating stars called Cepheid variables. Cepheid stars are dying, and their outer layers of helium gas grow and shrink as they absorb and release the star's radiation, making them periodically flicker like distant signal lamps.

As Cepheids get brighter, they pulsate more slowly, giving astronomers a means to measure their absolute brightness. By comparing this brightness to their observed brightness, astronomers can chain Cepheids into a "cosmic distance ladder" to peer ever deeper into the universe's past. With this ladder in place, astronomers can find a precise number for its expansion from how the Cepheids' light has been stretched out, or red-shifted.

Related: Mysterious 'unparticles' may be pushing the universe apart, new theoretical study suggests

But this is where the mystery begins. According to Cepheid variable measurements taken by Riess and his colleagues, the universe's expansion rate is around 74 km/s/Mpc: an impossibly high value when compared to Planck's measurements. Cosmology had been hurled into uncharted territory.

"We wouldn't call it a tension or problem, but rather a crisis," David Gross, a Nobel Prize-winning astronomer, said at a 2019 conference at the Kavli Institute for Theoretical Physics (KITP) in California.

Initially, some scientists thought that the disparity could be a result of a measurement error caused by the blending of Cepheids with other stars in Hubble's aperture. But in 2023, the researchers used the more accurate JWST to confirm that, for the first few "rungs" of the cosmic ladder, their Hubble measurements were right. Nevertheless, the possibility of crowding further back in the universe's past remained.

To resolve this issue, Riess and his colleagues built on their previous measurements, observing 1,000 more Cepheid stars in five host galaxies as remote as 130 million light-years from Earth. After comparing their data to Hubble's, the astronomers confirmed their past measurements of the Hubble constant.

"We've now spanned the whole range of what Hubble observed, and we can rule out a measurement error as the cause of the Hubble Tension with very high confidence," Riess said. "Combining Webb and Hubble gives us the best of both worlds. We find that the Hubble measurements remain reliable as we climb farther along the cosmic distance ladder."

In other words: the tension at the heart of cosmology is here to stay.

What it is: ESO 420-G013, an extremely bright face-on spiral galaxy harboring a hungry black hole

When it was taken: Jan. 30, 2024

Where it is: 50 million light-years from Earth in the constellation Sculptor

Why it's so special: This image from the Hubble Space Telescope captures the dark dust lanes of a rare kind of spiral galaxy against the glow of thousands of stars.

The image shows a bright core and brownish filaments of dark dust, but the galaxy's almost perfectly round disk is its most notable feature. That's because Hubble, which has been in orbit around Earth since 1990, just happens to have a direct face-on view of ESO 420-G013.

Besides being a fine example of a spiral galaxy, ESO 420-G013 is a Seyfert galaxy. Named after American astronomer Carl Keenan Seyfert, who researched the objects in 1943, a Seyfert galaxy has an extremely bright, point-like active galactic nucleus powered by a supermassive black hole, according to a NASA statement. Deep within ESO 420-G013, its hungry black hole is pulling in surrounding material and sending out powerful radiation. It's also forming new stars at a high rate.

Related: Right again, Einstein: New snapshot of 1st black hole to be photographed confirms relativity

Seyfert galaxies like this one are visible in the infrared — wavelengths of light beyond those visible to humans in the electromagnetic spectrum — which Hubble can detect thanks to its Wide Field Camera 3, which is sensitive to ultraviolet, visible and infrared light.

What's special about ESO 420-G013 is its visibility. Most galaxies with active galactic nuclei host black holes so bright that their radiation entirely obscures the light of the host galaxy. However, Seyfert galaxies such as ESO 420-G013 are distinct, because the surrounding galaxy structure can be clearly detected.

ESO 420-G013 was captured by Hubble as part of research on luminous infrared galaxies, which are known for their intense brightness in the infrared spectrum.

What it is: The irregular dwarf galaxy UGC 8091

When it was unveiled: Jan. 1, 2024

Where it is: 7 million light-years away, in the constellation Virgo

Why it's so special: We live in a "grand design" galaxy, with two prominent spiral arms that together contain up to 100 billion stars, according to NASA. But how the Milky Way and other similar galaxies became so structured and well defined is a mystery to astronomers. Could the key be tiny, messy galaxies like UGC 8091? 

Imaged here by the Hubble Space Telescope, UGC 8091 is an irregular dwarf galaxy thought to exist in the same Local Group as the Milky Way. Astronomers think there are about 20 galaxies in this cluster, most of them either elliptical — the oldest and most evolved type of galaxy — or spiral, like the Milky Way. Loose, messy dwarf galaxies like UGC 8091 are often referred to as "galactic building blocks," since larger, more complex galaxies are thought to grow as smaller ones merge, according to the Hubble website. Dwarf galaxies may have helped to reheat the hydrogen that had cooled as the universe expanded after the Big Bang, according to NASA.

The red regions of the image are likely interstellar hydrogen molecules that are glowing because they have been excited by the light from hot, energetic stars, according to NASA. The image also shows older stars and, in the background, distant galaxies.

The image was created using data from Hubble's Wide Field Camera 3 and Advanced Camera for Surveys between 2006 and 2021. Twelve camera filters were needed to make the image, because the Hubble data includes light the human eye cannot see, from mid-ultraviolet to the red end of the visible spectrum.

The universe is expanding. But depending on where we look, it's doing so at bafflingly different speeds.

The problem is known as the Hubble tension, and it centers around figuring out a number for the universe's expansion rate, called the Hubble constant. To find it, scientists have pored over tiny fluctuations in the cosmic microwave background (CMB) — an ancient relic of the universe's first light — and built cosmic distance ladders to remote, pulsating stars called Cepheid variables.

But the best experiments using these two methods disagree. The difference in results may have seemed small, but it was enough to spark a major crisis in cosmology.

Wendy Freedman, an astrophysicist at the University of Chicago, has spent four decades studying the Hubble constant.

Now, she is using one of the most powerful tools in astronomy — the James Webb Space Telescope (JWST) — to get the most precise measurements yet of the Hubble constant. Her team is looking at several celestial objects at the same distance from Earth. The hope is with several measurements in hand, the tension can finally be resolved one way or another. 

Live Science spoke to Freedman about how the tension arises, why it matters, and how she's using the JWST to hunt for an answer.

Related: After 2 years, the James Webb Telescope has broken cosmology. Can it be fixed?

Ben Turner: You've been measuring the Hubble constant for a large part of your scientific career. What drew you to studying it? And why is it such an important measurement for cosmologists to know?

Wendy Freedman: The Hubble constant gives you a measure of the size of the universe, and it's probably the most fundamental parameter that we can measure that tells us about the evolution of the universe. 

What drew me to it is the fact that you could make measurements in our local neighborhood — which, of course, astronomically speaking, is a large neighborhood — and use them to learn things about the early universe and how it grew. It really intrigued me.

BT: How important is the standard model of cosmology? What is the Hubble tension?

WF: The standard model [which explains how the universe has expanded since the Big Bang] is an interesting model in the sense that we are made of what is a very small fraction of the overall amount of matter and energy in the universe. 

And so there are very fundamental things that we don't understand. We don't know yet what dark matter is. Neither do we know what dark energy is, except that it's causing the universe to speed up. But the model works remarkably well, given that we don't understand its fundamental structure. 

The Hubble constant gives us an opportunity to learn something more about the universe in that way. We test the standard model by making measurements locally, and then compare them with what we find in the early universe by measuring fluctuations in temperature across the cosmic microwave background. 

You can fit the standard model to those cosmic microwave background measurements, and it's an astoundingly good fit. And because the standard model is a predictive model you can work forwards, using data from the cosmic background radiation to predict what the Hubble constant should be today. 

But if we compare that predicted value of the Hubble constant to what we measure using stars called Cepheid variables, they don't match — that's the Hubble tension.

BT: If we accept that the Hubble tension is real and not a systematic error somehow, how big a challenge is it to the standard model of cosmology?

WF: At this point I have a completely open mind [on whether it's real]. I don't know which way this is going to go. But yes, it would be significant. How significant? Probably not as significant as the standard model itself. But if it led to a newer, fundamental understanding that improves our knowledge of these things that really remain mysteries at the moment, it could be profound.

BT: So let's dig into how we measure this. Besides the fluctuations in the cosmic microwave background, Cepheid variables are the other main way astronomers find a value for the Hubble constant. What are Cepheid variables, and how do we use them to measure astronomical distances?

WF: Cepheid variables were what Edwin Hubble used when he discovered the expansion of the universe. They're stars that are five to 20 times more massive than our own sun, and they have atmospheres that are actually pulsating — moving in and out — with time. They do this in a very regular way for periods of a couple of days, going through up to 100 or so cycles in their light levels.

In the early 1900s, Henrietta Leavitt found that there was a correlation between how fast Cepheid stars were pulsating and how bright they are. That gives us a means of measuring distance, and it's one of the most accurate means that astronomers have today.

If we can measure nearby stars in a way that we can determine their distance, say from geometry. Then we can look at Cepheid variables in galaxies, compare their brightnesses at a given period — using the period luminosity relation — and then by the inverse square law of light [light dims from a source in proportion to the square of the distance to its viewer] we get the distance.

BT: And yet despite being very accurate, there are a lot of uncertainties associated with Cepheid measurements. What are they? And what are researchers doing to account for them in their measurements?

WF: There are complications. There's dust between us and the Cepheids that make them dimmer; their atmospheres contain different amounts of heavy elements that can change the brightness [meaning they have a high metallicity]; and there are just uncertainties in the measurements.

Also when we go to more distant galaxies, it's very difficult to make a measurement of a Cepheid on its own because other stars in the galaxy contribute light that's hard to separate from the Cepheid itself.

We've been improving the accuracy of these measurements for decades. Before the turn of the century, we were arguing about Hubble constants from Cepheids being between 50 to 100 [kilometers per second per megaparsec] — literally a factor of two uncertainty. As of 2001, our group published a result that gave a value of 72 [km/s/Mpc] with 10% uncertainty. That value stood the test of time: If we view Cepheids today we get numbers like 72, 73 and 74.

BT: But when we look at recent measurements of the cosmic microwave background taken by the Planck satellite, we get a value of around 67. At first glance, that looks like a difference of at most 7 km/s/Mpc, maybe even less. At a casual glance, that’s not very big, so why does it matter?

WF: Where the tension has arisen is that, in the last several years, it's been possible to make really accurate measurements of small differences in temperature in the cosmic microwave background. We're talking really small — like a thousandth of a percent.

You measure these fluctuations accurately and you can fit the standard model of cosmology incredibly well to this spectrum of temperature differences. From that, you can infer that the Hubble constant is 67.

Now there seems to be this discrepancy between 67 and 73. That doesn't sound like a lot given that we started between 50 and 100. In fact, Hubble started off at 500 when he first made his measurements. But because the measurements are improving in their accuracy, it appears as if it might be quite significant.

BT: So how are you looking for an answer?

WF: Why I'm excited right now is because we have the opportunity with the James Webb Space Telescope to make measurements of Cepheids and also other kinds of stars.

We've talked about systematic errors from dust and metallicity and so on. Each method we're going to use is going to have its own set of systematic uncertainties. No matter how many times we make the measurement more accurate — those systematics are going to get you in the end if you don't understand what they are.

So what we did in the past was take precise measurements of stars at the tip of the red giant branch [which also pulsate regularly] as a comparison. We got results for that coming in at around 70. Within their uncertainties they agreed pretty well with the Cepheids, but they also agreed pretty well with the cosmic microwave background.

Our current JWST program is to measure the Cepheids, tip of the red giant branch stars and a third star known as a JAGB star [aging carbon stars with a near-constant brightness] in the same galaxy, all at one distance. We'll see how well we agree and that will give us a sense of an overall systematic answer.

BT: Very briefly, why are tip of the red giant branch stars a useful comparison to make with the Cepheids?

WF: They’re older stars or lower mass stars — they don't have much of a metallicity dependence. We don't understand the metallicity dependence of the Cepheids well, that's still something that remains unsolved.

Also Cepheids are young, so they haven't had time to diffuse away from the regions where they were formed. They're in crowded high surface density regions, whereas the red giants are isolated. So it’s very simple to make a measurement in terms of their luminosity.

BT: Are there any results you can tease? How soon will you get them?

WF: Not yet, our group right now is blinded so we're not going to do an absolute calibration in the distance field until we have all the data measured and analyzed. We have to measure the periods and luminosities of the Cepheids, create a period-luminosity relation and (along with the JAGB stars) measure these luminosities. We're not going to unblind until all that analysis is done. We'll sit down in a room and we'll know.

So I don't know in terms of the absolute [distance] calibration. But what I can say, about our database and the reason we put in this big proposal to use JWST, is that it's got four times the resolution of the Hubble Space Telescope at infrared wavelengths. This means the star crowding issue is alleviated enormously and we have a test using a different filter to look for metallicity effects directly where we're observing. So I think we're going to be able to get at many of these systematic effects.

Where the Hubble constant is going to fall from this I just don't know right now. But we're really excited because I think we're gonna have something really interesting to say. In our first galaxy we see a lot of differences from the Hubble [Space Telescope] measurements — those stars were really crowded. Now we're looking at galaxies that are not quite as crowded.

As I said, I'm just completely open. I don't know where this is going to fall. But it is a question. It's an empirical question.

Editor's Note: This interview has been edited and condensed for clarity.

The "forbidden" light of a distant spiral galaxy shines brightly in a new image from the Hubble Space Telescope.

Located about 275 million light-years from Earth, the galaxy, called MCG-01-24-014, has two prominent, well-defined spiral arms and an energetic glowing core known as an active galactic nucleus (AGN). The galaxy is seen face-on with its arms creating a nearly perfect circular shape.

MCG-01-24-014 is classified as a Type-2 Seyfert galaxy, which is one of the two largest groups of active galaxies scientists know of, along with quasars. Seyfert galaxies exhibit a characteristic bright core, but are less detectable when compared to quasars — whose incredibly luminous AGNs can outshine the entire host galaxies within which they reside, according to a statement from the European Space Agency (ESA).

Seyfert galaxies can also be further categorized based on the intensity of light being emitted from their active cores. Depending on the wavelengths of light, or spectra, Seyfert galaxies are classified as either Type-1 or Type-2. The latter emit spectral lines associated with so-called "forbidden" emissions, given they should not exist according to certain rules of quantum physics.

"To understand why emitted light from a galaxy could be considered forbidden, it helps to understand why spectra exist in the first place," ESA officials said in the statement. "Spectra look the way they do because certain atoms and molecules will absorb and emit light very reliably at very specific wavelengths."

Related: James Webb telescope finds an 'extreme' glow coming from 90% of the universe's earliest galaxies

Electrons — the tiny particles that orbit the nuclei of atoms — lose or gain specific amounts of energy, which correspond to certain light wavelengths being absorbed or emitted. However, certain spectral emission lines are considered to be "forbidden" because they are observed in space but do not occur under normal conditions on Earth.

"Quantum physics is complex, and some of the rules used to predict it use assumptions that suit laboratory conditions here on Earth," ESA officials said in the statement. "Under those rules, this emission is 'forbidden' — so improbable that it’s disregarded. But in space, in the midst of an incredibly energetic galactic core, those assumptions don’t hold anymore, and the 'forbidden' light gets a chance to shine out towards us."

Indeed, the bright light from MCG-01-24-014 shines radiantly in the new Hubble photo, which was taken using the telescope's Advanced Camera for Surveys (ACS). The spiral galaxy appears in the center of the image, with two large bright stars in the foreground, one blue and one red, positioned directly above the galaxy itself. Several more distant galaxies are scattered across the otherwise pitch black backdrop of space. ESA released the new Hubble photo online on Dec. 18.

Originally posted on Space.com.

What it is: spiral galaxy NGC 1566. 

When it was taken: Nov. 3, 2023. 

Where it is: 60 million light-years away in the constellation Dorado. 

Why it's so special: NGC 1566 is a spiral galaxy whose twirling arms of stars inspired its informal nickname: the "Spanish Dancer." 

The Dancer is one of the most visually spectacular galaxies we can see, largely because of its orientation. While some galaxies are seen side-on from Earth — meaning we only see the thinnest part of the galaxy — NGC 1566 is seen face-on, making its bulge and spiral arms clearly visible.

This image of NGC 1566 from the Hubble Space Telescope shows two spiral arms of stars and lanes of dark dust swirling from a glowing galactic core, where the dust appears to split into fibers. Bright pink regions sparkle along the spiral arms where new stars are forming.

Around 60% of galaxies are spirals like NGC 1566, including our Milky Way. Spiral galaxies are home to stars that are, on average, much younger than those in other galaxies. According to NASA, spiral galaxies may evolve into elliptical galaxies, which are less structured and where stars are older — possibly after colliding or merging with other spiral galaxies.

The image of NGC 1566, taken using Hubble's Wide Field Camera 3 — one of its two main cameras — can be downloaded in up to 16-megapixel quality. There is also an online zoomable version.

Hubble launched in 1990 and has been orbiting Earth for 33 years. It entered safe mode in late November after suffering problems with one of its three gyroscopes, which help it turn and lock on to new targets. However, it resumed science operations on Dec. 8, according to NASA.

NASA has combined the power of its two premier space telescopes to produce one of the most colorful and comprehensive views of the universe ever. 

Using data from the James Webb Space Telescope (JWST) and Hubble Space Telescope to collect light in different wavelengths, a new, combined image reveals a parade of stars and galaxies within the massive galaxy cluster MACS0416, 4.3 billion light-years from the solar system. While JWST detects infrared light invisible to humans, Hubble detects visible light; the resulting panchromatic image creates colors that help astronomers measure vast cosmic distances. 

For example, a landscape of galaxies in blue and red can be seen surrounding the yellowish line of lights that make up MACS0416. The bluest galaxies, which mostly come from Hubble's data, are both the closest to Earth and the busiest hotbeds of star formation. The redder galaxies are much dustier and farther away. They're the work of JWST's infrared instruments, which can detect heat signatures through dust clouds. 

Related: James Webb telescope discovers 'Cosmic Vine' of 20 connected galaxies sprawling through the early universe

The image also includes concentric circles curving around MACS0416. They're actually objects far behind, magnified by MACS0416's gravitational field. This gravitational lensing occurs when a massive foreground object distorts the space around it and bends the light from objects behind it. The result of this chance alignment is often referred to as a "cosmic magnifying glass," which both reveals and magnifies objects. 

One of those magnified objects in the new image is an enormous star, nicknamed "Mothra." It's being magnified by a factor of at least 4,000 times, according to NASA. 

"We're calling MACS0416 the Christmas Tree Galaxy Cluster, both because it's so colorful and because of these flickering lights we find within it," said Haojing Yan, professor of astronomy at the University of Missouri and lead author of a new paper describing the results, said in a NASA statement. The paper, available on the preprint database arXiv, has been accepted for publication in The Astrophysical Journal.

The image could be the first of many like it. Since 2014, Hubble has been busy imaging the faintest and youngest galaxies ever detected. And JWST is now adding valuable data about the early universe.

"The whole picture doesn't become clear until you combine Webb data with Hubble data," Rogier Windhorst, professor of astronomy at Arizona State University and principal investigator of the Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS) program, which took the Webb observations, said in the statement. "We are building on Hubble's legacy by pushing to greater distances and fainter objects." While Hubble images took 122 hours to produce, JWST's — collected nine years after Hubble's — took just 22 hours.

What it is: The Soul Nebula (also called Westerhout 5 or IC 1848) and a star-forming bubble within it

When it was taken: Sept. 29, 2023

Where it is: 7,000 light-years from Earth in the constellation Cassiopeia, in the Perseus spiral arm of the Milky Way galaxy

Why it's so special: A beautiful new Hubble Space Telescope image published in late September shows a dark, tadpole-shaped object within a sea of red.

That sea is a nebula — a huge cloud of dust and gas in space — called the Soul Nebula. Specifically, it's an emission nebula — a bright, diffuse cloud of electrically charged gas that emits its own light, according to NASA. The nebula is red because it's emitting H-alpha light, which is the result of electrons within hydrogen atoms releasing light as they become less energetic.

Related: 25 gorgeous nebula photos that capture the beauty of the universe

Published to coincide with the fall foliage season in the Northern Hemisphere, the image's bright-red light is home to what astronomers call an evaporating gaseous globule (EGG). Like all EGGs, the dark, tadpole-shaped EGG in this nebula's upper center left is a dense, compact pocket of molecular hydrogen gas found in star-forming regions, according to HubbleSite. Besides the acronym, there's another reason for the "EGG" name: These bubbles of interstellar gas are dense enough to collapse under their own weight to form young stars, akin to eggs hatching to reveal the babies within.

However, this EGG — named KAG2008 globule 13 and J025838.6+604259 — is different from most. While other EGGs are connected in a nebula, this one is a detached free floater — a "frEGG" — with a distinct "head-tail" shape. Ultraviolet radiation from stars can make it harder for baby stars to thrive, but the gas within frEGGs and EGGs is so dense that the "eggs" act as cocoons that help baby stars form.

How to see it in the night sky: The Soul Nebula is part of the star-forming Heart and Soul Nebula (IC 1805), a popular deep-sky sight for telescopes in the Northern Hemisphere winter.

China is readying a major project that not only augments the nation's astronomical research agenda but bolsters the use of the country's space station complex. 

And there are bragging rights associated with China's star-studded venture. 

The spacecraft is called Xuntian, known as the Chinese Survey Space Telescope or the Chinese Space Station Telescope (CSST). The name "Xuntian" can be literally translated as "surveying the sky" or "survey of the heavens."

Scheduled for launch next year, the bus-sized CSST houses a two-meter (6.6 foot) diameter primary mirror. This ultraviolet-optical space telescope is to co-orbit with the country's Tiangong space station. It has a nominal mission lifetime of 10 years, but the observatory's space duties could be extended.

Xuntian is designed to outdo NASA's Hubble Space Telescope. This large orbiting facility is to orbit near China's space station where it can be overhauled from time to time by Chinese spacewalkers.

Lin Xiqiang, deputy director of the China Manned Space Agency, has stated that the Xuntian in-orbit observatory is expected to make breakthroughs in cosmology, dark matter and dark energy, the Milky Way galaxy and other neighboring galaxies, star formation and evolution and exoplanets.

That's a tall order. 

Lin said that the high-resolution telescope will take deep-field survey observations with an area of 17,500 square degrees, as well as make fine observations of different types of celestial bodies. Xuntian is endowed with a 2.5 billion pixel camera.

Field of View

Expected to be hurled into Earth orbit next year atop a Long March 5B rocket, Xuntian can obtain high-definition panoramic views of the universe having roughly the same spatial resolution as the Hubble Space Telescope. However, China's orbiting eye has a field of view more than 300 times larger than Hubble. The field of view is the area of the heavens a telescope can see at one time.

In an interview last year with China's state-run Xinhua news agency, Li Ran, project scientist of the CSST Scientific Data Reduction System, used the analogy of imaging a flock of sheep to point out CSST's capabilities.

"Hubble may see a sheep but the CSST sees thousands, all at the same resolution," Li said.

Moreover, this super-scope will stay in the same orbit as the space station for long-term independent flight and observations. It is designed to temporally dock with the space station for hands-on supply, maintenance and upgrading by Tiangong astronauts, Lin said.

High tech

In an interview with China Central Television (CCTV), Zhou Jianping, chief designer of the China manned space program, also heralded Xuntian's planned capabilities and contributions.

"The Xuntian telescope has been the most important scientific project since the launch of our country's space station program. It is a scientific facility that Chinese astronomical community has eagerly anticipated, and a scientific facility representing the state-level high tech in astronomy," Zhou said.

The telescope is also the most advanced in terms of its ability to produce images in the ultraviolet spectrum among all the ongoing telescope research projects in the world, added Zhou. "It's expected to greatly boost the development of astronomy, advance our country's astronomy research to an international leading level and help Chinese astronomers become a leading force in this field."

First generation

According to Li Chengyuan of the School of Physics and Astronomy at China's Sun Yat-sen University, the China Space Station Telescope and NASA's Hubble Space Telescope are sensitive to a similar wavelength interval.

But Xuntian covers a field of view which is about 5 to 8 times wider than that of Hubble, Li emphasized last year in the journal Research in Astronomy and Astrophysics.

The "first-generation" Xuntian space telescope consists of five observation instruments, including the Xuntian module, the terahertz module, the multichannel imager, the integral field spectrograph and the extrasolar planetary imaging coronagraph.

The Xuntian module, a camera with a wide field of view, will take up major observation time.

Test and assembly

During its normal observations, the space telescope will fly independently in the same orbit as China's space station, but at a faraway distance.

"We are still developing the prototype sample. Currently, we've completed the development of all subsystems, components, and units, and we are preparing for the test after they are assembled," said Xu Shuyan, chief designer of the Xuntian optical facility and researcher from the National Astronomical Observatories of the Chinese Academy of Sciences.

"After this, we will start the development of the telescope sample, and start the research of the flying parts. Then we will conduct the joint test with the Xuntian platform and the test at the launch base, before it is launched," Xu told CCTV.

World-class center

In the big picture world of expanding the frontiers of space astronomy you need to look no further than the achievements of the Space Telescope Science Institute (STScI) in Baltimore, Maryland. STScI is a multi-mission science operations center for NASA's flagship observatories and a world-class astronomical research center.

STScI is home-base for wow-making science programs utilizing the James Webb Space Telescope, the Hubble Space Telescope and will be the science operations center for the Nancy Grace Roman Space Telescope launching in the mid-2020s.

The institute is located on the campus of Johns Hopkins University in Baltimore, Maryland, and is operated by the Association of Universities for Research in Astronomy for NASA.

Open questions

While Chinese space agency leaders are already boasting about the capabilities of Xuntian, some researchers have their doubts.

"For facilities open to the international scientific community, such as Hubble or Webb, we provide significant documentation and software so that researchers can plan outstanding science programs," said Tom Brown, an astronomer and head of the Hubble Mission Office at STScI.

"In contrast, not a lot is publicly known about the specific capabilities of the China Space Station Telescope, so it is difficult to judge how it will enable similar investigations," Brown told Space.com.

From the little that is known, Brown said it seems like China's Space Station Telescope will have a larger field of view than Hubble, but a smaller mirror, with less collecting area and spatial resolution.

The spectral resolution appears to be significantly lower than that available on Hubble, and CSST does not extend into the far-ultraviolet, that is, below 200 nanometers.

"There are a lot of open questions at this point," said Brown, including if the space-based telescope can be successfully launched, if it can be maintained in a space station environment, how observing time will be peer reviewed and awarded and how the data will be calibrated.

"Hubble continues to lead the field in all the ways one measures the worth of a world-class research facility, pursuing ground-breaking projects in all areas of astrophysics," Brown said. "I am curious to see how the China Space Station Telescope story unfolds."

Originally posted on Space.com.

What it is: Arp 142, a pair of interacting galaxies

When it was taken: June 20, 2013

Where it is: 326 million light-years from Earth, in the constellation Hydra.

Why it's so special: Showcased recently by the European Space Agency, this stunning image of a couple of interacting galaxies creates the illusion of a birdlike figure guarding an egg.

Is it a hummingbird, a penguin, or a sneaky porpoise creeping up onto the beach? Arp 142 is a fabulous example of pareidolia, the human tendency to see familiar objects or patterns in unrelated objects. However, its two galaxies are very much related in that they're gravitationally interacting with each other.

Related: 15 Martian objects that aren’t what they seem

This image shows a standard spiral galaxy called NGC 2936 and a small elliptical galaxy called NGC 2937. When two galaxies get too close to each other, their gravity begins to warp each other. Sometimes, the galaxies merge, but other times, they rip each other apart.

If you study the twisted remains of the larger spiral galaxy, you can see the leftovers of its bright core as the "eye'" of the bird — but its once-spiraling arms of stars are now warped streaks of blue and red in the bird's body.

Although the image was created in 2013, it's resurfaced recently as scientists use the Hubble Space Telescope to finish cataloging so-called peculiar galaxies. In September, Hubble added Arp 107 as the space telescope used its Advanced Camera for Surveys to observe members of the Atlas of Peculiar Galaxies, all of which are interacting and merging. That catalog was initially published in 1966 by American astronomer Halton Arp (this peculiar galaxy’s namesake).

The image of Arp 142 — a combination of visible and infrared light — was taken by Hubble's Wide Field Camera 3, which was installed in 2009 by astronauts on Space Shuttle Atlantis, according to NASA. It was the final servicing mission, and the space telescope hasn't been visited since.

What it is: Arp 107, a pair of galaxies mid-collision.

When it was taken: Sept. 18, 2023.

Where it is: 465 million light-years from Earth in the constellation Leo Minor. 

Why it's so special: This image from the Hubble Space Telescope captures the cosmic collision of two very different types of galaxies.

While the large galaxy on the left shows a single spiral arm curving out from its core, with dust and gas glowing throughout, the much smaller galaxy on the right is little more than a bright core. Linking the two odd-looking galaxies is a tenuous bridge of dust and gas.

The larger galaxy is a Seyfert galaxy — a spiral galaxy that has an extremely bright, point-like active galactic nucleus powered by a supermassive black hole, according to NASA. About one in 10 galaxies are Seyfert galaxies.

Interacting and merging galaxies — including Arp 107 — were first cataloged by American astronomer Halton Arp (hence their name), who in 1966 published his Atlas of Peculiar Galaxies. In recent years Hubble has used its Advanced Camera for Surveys to make observations of these galaxies, including Arp-Madore 417-391 and the spectacular galactic triplet Arp 248.

How to see it in the night sky: These galaxies are very difficult to see, even when Leo Minor is high in the sky over the Northern Hemisphere in spring. However, a similar-looking sight can be viewed in a good telescope by pointing it at M51, better known as the Whirlpool galaxy. Found between Alkaid at the end of the handle of the Big Dipper and the star Cor Caroli in the constellation Canes Venatici, the Whirlpool consists of one large spiral galaxy interacting with a dwarf galaxy right alongside it. They're 27 million light-years from the Milky Way but are a bright and easy sight for even a small telescope.

Using the Hubble Space Telescope, a team of astronomers has used a tricky technique to discover an elusive 11-billion-year-old galaxy. Rather than observe the light this realm emits, they watched for the light it absorbs.

Just as we see a light bulb via the light it emits, astronomers usually observe galaxies using the light their stars emit. Galaxies put out light waves found across the entire electromagnetic spectrum, and  different telescopes are able to observe these cosmic objects in different wavelengths of light to form a full picture.

But, when a galaxy is located along the same line of sight as another, more distant, source of bright light, there's another way to go about these galactic observations. As light passes through a background galaxy toward a foreground galaxy, for instance, gas and dust in the foreground galaxy will absorb some of the background one's wavelengths. And because chemical elements absorb light at specific wavelengths, looking for gaps in the light output  —  or spectra  —  from a background source can tell astronomers what that light had passed through on its way to our telescopes. In other words, light in those "gaps" would've been absorbed by a foreground object on the way to our vantage point.

Related: The closest black holes to Earth may be lurking in a star cluster visible to the naked eye

One potentially useful background source for this technique are quasars, which are extremely bright galactic hearts powered by supermassive black holes blasting out jets of radiation and matter as they feast on surrounding material.

"To find absorbing galaxies, we first look for quasars that are particularly red," Johan Fynbo, an astronomer at the Cosmic Dawn Center, said in a statement. "Because star dust tends to absorb the blue light but not the red, if there is a dusty galaxy in the foreground, the quasar will be reddened."

He and his team have spotted several absorbing galaxies by parsing light from reddened quasars, but once this is done, they are faced with a much more challenging task: hunting for  light emitted by the absorbing galaxy itself.

A firefly on a cosmic lighthouse

When situated exactly behind a galaxy, quasars tend to disrupt our view of foreground galaxies because they are so immensely bright. So much so that they essentially overwhelm the combined light of every star in an entire galaxy.

This makes spotting an absorbing galaxy with its own light output akin to trying to spot a firefly perched on the lamp of a lighthouse while standing onshore. While this might prove too intimidating a challenge for many, however, Fynbo and colleagues relish it.

Unfortunately, the scientists haven’t yet identified the light coming from  their recently-uncovered, 11-billion-year-old absorbing galaxy, but the absorption patterns this object has revealed are remarkable. The galaxy, seen as it was when our 13.8 billion-year-old universe was only around 3 billion years old, is absorbing more light than other galaxies found in a similar fashion, meaning it is likely a more mature galaxy such as the Milky Way.

"The features that we found in the missing light tell us something about the dust in the foreground galaxy," Lise Christensen, a member of the discovery team and an astronomer at the  Cosmic Dawn Center,  said in the statement. "In fact, the dust seems to resemble the dust that we see locally in the Milky Way and one of our neighboring galaxies."

The team was also able to determine that the galaxy has a bright counterpart. That galaxy, which seems to be birthing stars at an intense rate, is so close to the absorber galaxy that the team also believes the two are probably gravitationally bound. This means ,at some point after they were noticed, the two galaxies likely formed a galaxy group similar to  the local group in which the Milky Way sits.

Fynbo intends to revisit this region of space with other instruments, including the Nordic Optical Telescope at La Palma, to search for other members of this galactic group  in the hope he will be able to see the absorbing galaxy emit light of its own.

"This makes the galaxies even more interesting to study," the astronomer concluded.

The team’s research has been accepted for publication in the journal Astronomy & Astrophysics. Meanwhile, a pre-peer review version is available on the research repository arXiv.

Originally posted on Space.com.

The famed Hubble Space Telescope tracked dramatic hour-by-hour changes in deep space caused by a NASA probe's deliberate asteroid crash. 

NASA's Double Asteroid Redirection Test (DART) mission slammed into a small space rock called Dimorphos in late September 2022, aiming to test-drive a technique for deflecting an asteroid on a collision course with Earth. (There are no imminent asteroid threats to our planets, but practice makes perfect.)

Fresh imagery from the Hubble Space Telescope released today (March 1) shows dust and debris flying at high speed away from Dimorphos and its larger asteroid companion, Didymos, after DART's impact. The collision is believed to have thrown about 1,000 tons of ancient asteroid material into space. 

Related: Behold the 1st images of DART's wild asteroid crash!

"We've never witnessed an object collide with an asteroid in a binary asteroid system before in real time, and it's really surprising. I think it's fantastic. Too much stuff is going on here. It's going to take some time to figure out," Jian-Yang Li of the Planetary Science Institute in Tucson, Arizona, said in a statement released by the Space Telescope Science Institute (STScI) in Baltimore, which operates Hubble's science program. 

The fresh imagery was accompanied by a study, led by Li in collaboration with 63 other DART team members, on Wednesday (March 1) in the journal Nature. The paper is one of five published in Nature Wednesday, which together give a detailed overview of the DART impact and its aftermath.

Information based on Hubble's work indicates at least three stages of Dimorphos debris evolution. First an ejecta cone was formed, then the debris furled into the asteroid's orbit, and finally the tail moved behind the asteroid due to the pressure of the solar wind, the stream of charged particles flowing constantly from our sun.

The newly released Hubble movie begins with footage from roughly 1.3 hours after impact, showing Dimorphos and Didymos at such a distance that the two space rocks cannot be resolved individually. Roughly 2 hours after the event, you can see debris moving at speeds exceeding 4 mph (6.4 kph) an hour, fast enough to overcome the gravitational pull of the asteroid system.

The cone shape began forming about 17 hours after impact. "The most prominent structures are rotating, pinwheel-shaped features. The pinwheel is tied to the gravitational pull of the companion asteroid, Didymos," STScI officials wrote in the statement.

Then the last stage shows debris sweeping behind the asteroid, "where the lightest particles travel the fastest and farthest from the asteroid," STScI officials added. But the processes have yet to be understood, as Hubble saw the tail splitting into two streams for a few days and the mechanism by which that happened is not clear.

Numerous instruments on Earth and in space imaged the DART impact, and more results will come from these various investigations as the data is parsed, understood and processed.

Elizabeth Howell is the co-author of "Why Am I Taller?" (ECW Press, 2022; with Canadian astronaut Dave Williams), a book about space medicine. Follow her on Twitter @howellspace.

Originally posted on Space.com.

Astronomers have finally weighed an isolated white dwarf, or the shriveled husk of a dead star, using a strange phenomenon predicted by Einstein's theory of relativity decades ago.

The findings confirm astronomers' predictions about how massive white dwarfs can be, and may help explain the strange, ultra-dense matter that makes up these stellar leftovers.

In the new study, astronomers used the legendary Hubble Space Telescope to measure the mass of a standalone white dwarf called LAWD 37, according to a study published in the March issue of the journal Monthly Notices of the Royal Astronomical Society. Although astronomers have weighed white dwarfs in binary star systems — systems where two stars orbit a common center of mass — LAWD 37 is the first white dwarf to be measured in isolation.

The research team, led by University of California Santa Cruz astronomer Peter McGill, used a quirky property of the universe to make this pioneering measurement: the fact that gravity warps space-time. As LAWD 37 passed in front of a distant bright star, the light from the background star bent around the nearby white dwarf in a process known as gravitational microlensing, originally predicted by Albert Einstein. When LAWD 37 warped the star’s light, the star appeared to shift ever so slightly in the sky — an effect Hubble can detect with incredible precision.

"These events are rare, and the effects are tiny," said McGill in a NASA statement. "For instance, the size of our measured offset is like measuring the length of a car on the Moon as seen from Earth." This extremely precise measurement took years of observations with Hubble to acquire.

Ghostly white dwarfs

Many stars, like our sun, don’t end with a bang. Instead, they slowly expand and fade out, losing their outer layers and leaving behind their dead cores. These remnants, known as white dwarfs, are made of degenerate matter, a strange type of ultra-compressed gas scientists are still working to understand.

Located only 15 light-years from Earth, LAWD 37 has been a popular subject of study for many years. In their new research, the study authors used positioning data from the European Space Agency’s Gaia mission to predict precisely when LAWD 37 would pass in front of the distant star, allowing the team to prepare for the gravitational lensing event accordingly. Based on the distant star’s slight movement in the sky, the team calculated that the white dwarf is approximately 56% as massive as the sun, which agrees with existing models and predictions for what’s going on inside these strange stellar remnants.

This mass measurement is one of hopefully many more to come — including measurements based on new data from the James Webb Space Telescope. The team is already observing another white dwarf, LAWD 66, and will continue to watch it until they have enough information to measure its mass in 2024, uncovering yet another piece of the puzzle.