A new study using data from NASA’s Hubble Space Telescope finds that star formation in the nearby Andromeda galaxy has undergone a 500-million-year decline, with an even steeper drop in the last 40 million years. Andromeda, a spiral galaxy comparable in size to our Milky Way, is close enough to be seen with the unaided eye from areas with dark skies. Located about 2.5 million light-years from Earth, practically our cosmic backyard, Andromeda offers an opportunity for astronomers to examine its stellar populations in detail, leading to better understanding of the past of galaxies like our own.

The results published Monday in The Astrophysical Journal.

To reach this conclusion, the researchers combined data from two Hubble surveys: the Panchromatic Hubble Andromeda Treasury and the Panchromatic Hubble Andromeda Southern Treasury. Together, these two surveys mapped two-thirds of the disk of Andromeda in ultra-sharp detail. In total, the team measured about 200 million individual stars across the galaxy, giving them a detailed picture of Andromeda’s past activity.

“We need to measure the individual stars because they are the fossil record of the galaxy’s formation. 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,” said Ben Williams, astronomer at the University of Washington and a co-author on the study.

Massive stars are bluer and short-lived, while less massive stars are redder and longer-lived. As a result, areas that have experienced recent star formation tend to have a larger fraction of blue stars, while areas with less recent star formation typically have a redder population. The team divided the Andromeda images into thousands of squares, spanning 300 light-years on each side of the square, and determined the history of star formation within each parcel to gain a comprehensive view of the galaxy’s past.

Steady decline

Previous research showed the Andromeda galaxy experienced a dramatic burst of star formation about 2 billion years ago, likely due to a past interaction or merger with another galaxy. Since that time, star formation has been steadily declining.

Astronomers measure the rate of star formation in terms of the mass, or amount of gas and dust, converted into stars per year. The researchers calculated that, 500 million years ago, Andromeda formed stars at a rate of about one solar mass per year. However, the formation rate dropped to about half that by 40 million years ago. The current rate has plummeted even farther, to about one-fifth the mass of our Sun per year.

The team also examined whether that decline was consistent across the galaxy or concentrated in certain areas. They found that much of the recent star formation has occurred in a star-forming ring located about 32,000 light-years from the galaxy’s center. As a result, much of the decline they measure is driven by decreasing activity within that ring.

Rather than being the result of reduced material from which new stars can form, the decline is more likely to be a natural winding down from its previous, more active state.

“It’s just like after running a marathon, sometimes you’ve got to take a bit of a breather,” said Tobin Wainer, lead author, University of Washington.

Likely suspect

The team also investigated whether there was any connection between the decrease of activity in Andromeda and its proximity to satellite galaxy M32 (Messier 32). The M32 galaxy is separated from Andromeda by about 16,000 light-years in the plane of the sky; however, its 3D location in space is uncertain. As a result, astronomers are unsure if or when it might have interacted with Andromeda in the past.

“One of the major motivations for this program was to probe potential interactions between M32 and Andromeda’s disk,” said Zhuo Chen, co-author, University of Washington.

Survey data from the Panchromatic Hubble Andromeda Southern Treasury allowed the team to study the history of star formation in Andromeda near M32. They found that this area showed signs of decreased star formation compared with other regions. The timing of this decrease, which this study finds began roughly 60 million years ago, could help constrain when the M32 galaxy interacted with Andromeda’s disk.

“We can’t explicitly say that we are seeing a decrease in star formation because of M32. But it’s right there, and it’s definitely the most likely suspect,” said Wainer.

The team plans to continue analyzing the Hubble data and combine it with data from ground-based observatories to gain additional insights into the history of Andromeda.

“There’s a strong scientific value to this archival data. Andromeda is important because it’s a neighbor that is close enough that we can see it in great detail while also getting a global perspective,” said Raja GuhaThakurta, co-author, University of California Santa Cruz.

An even greater global perspective is likely to come from NASA’s Nancy Grace Roman Space Telescope after it launches as early as Sunday, Aug. 30. Roman’s gigantic field of view can cover at least 100 times as much area as Hubble at near-infrared wavelengths in a single observation. A newly approved Roman observing program will image the entirety of Andromeda’s disk and areas of its surrounding halo, allowing astronomers to measure hundreds of millions of stars and enabling groundbreaking new science.

The Hubble Space Telescope has been operating for more than three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.

 

The small exoplanets of our Sun’s second-nearest neighbor, Barnard’s Star, are inhospitable wastelands, British astronomers say.

Located six light-years from Earth, Barnard’s Star is separated from our closest neighbor, Alpha Centauri, by about 66° in our sky. Now, University of Cambridge researchers have revealed their findings on this exosolar system in a recent paper published in the Monthly Notices of the Royal Astronomical Society.

After careful analysis, the astronomers announced that the exoplanets are unlike any in our solar system, presenting a brutal and barren environment.

Barnard’s Star Exoplanets

Scientists only discovered these four small planets orbiting Barnard’s Star in 2025. Unlike anything in our solar system, these orbital bodies fit into a size range larger than Mars, but smaller than Earth or Venus.

Like a peeled onion, these smaller planets are rich in a mineral only found deep below the Earth’s surface. Chemical analysis revealed large amounts of the mineral periclase on the surface of these planets, something typically only found hundreds of kilometers deep on our planet.

“Barnard’s Star has an enormous amount of the element magnesium compared to other stars, so its planets are likely to be rich in magnesium too,” said lead author Xander Byrne from Cambridge’s Institute of Astronomy. “On Earth, that magnesium goes into making minerals called olivines, which are really important for storing water within the planet.”

A Lack of Water and Atmosphere

Unfortunately for those looking for extraterrestrial life, magnesium serves a different purpose on these exoplanets. Instead of water-storing olivine, it produces the abundant periclase, which is a poor store of water.

Even worse, these inhospitable exoplanets likely no longer have an atmosphere. According to the University of Cambridge team, these ten-billion-year-old planets probably only managed to hold an atmosphere for two billion years at most.

“These planets were always going to be hostile, because they’re really close to their star,” said Byrne. “Even the outermost planet orbits ten times closer than Mercury orbits the Sun. When you’re that close to your star, and have such little gravity, your atmosphere just gets blown off.”

In addition to the lack of atmosphere, the planets’ proximity to Barnard’s Star leaves them tidally locked, like our Moon, with one side always facing toward the star.

Exoplanet Stability

However, there is one positive element to these small planets. Typically, such close-orbiting systems are highly unstable, with the planets shooting out from the system, falling into their host star, or catastrophically colliding. Yet in this case, the system is as ordered as a piece of music. 

The three inner planets of the exosolar system have years in a 9:12:16 ratio, producing two of what is known as a “perfect fourth” in music. This musical harmony is known as an orbital resonance, with the same type of effect stabilizing Jupiter’s moons in their orbits around that planet. 

While our ability to view Barnard’s Star from Earth may be limited, the European Space Agency’s upcoming Plato mission may allow astronomers to discover ever smaller worlds orbiting in the nearby exosolar system.

“Larger planets are much easier to detect than small ones, so we know about very few sub-Earth planets like the ones in this system,” said Byrne. “But the sensitivity of these new missions will help to reduce this bias, allowing us to discover more and more planets that are small and rocky, like Earth.”

The true significance of the research may lie in the value of a null result. While these planets are bleakly hostile to life, observing this exosolar system’s composition can aid future astronomers in narrowing down the search for extraterrestrial life.

The paper, “The Barnard’s Star Planetary System: Stability, Composition, and Evolution of Four Sub-Earth Exoplanets,” appeared in Monthly Notices of the Royal Astronomical Society on June 24, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.

Born on July 25, 1920, Chushiro Hayashi graduated from the University of Tokyo with a degree in physics in 1942. After World War II service in the navy, he returned to school, finishing his doctorate in 1954 and becoming a professor at Kyoto University in 1957. An innovator, he applied fundamental physics to astronomy andContinue reading "July 25, 1920: The birth of Chushiro Hayashi"

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Chinese astronomers report the detection of a peculiar optical transient event that occurred in the center of a dwarf galaxy. The newly discovered event, designated AT2019ijn, is a fast-rising, slow-decaying blue optical transient with exceptionally bright radio emission. The finding was detailed in a paper published July 6 in The Astrophysical Journal Letters.

It was the 13th test overall of Starship. The success is a boon to NASA’s moon plans and SpaceX’s hopes to deploy a million data centers in orbit.

A careful statistical comparison of observations recorded by NASA's Juno mission and the Planetary Science Institute's Io Input Output observatory (IoIO) shows that IoIO observations reliably predict the density of Jupiter's plasma disk, an important part of Jupiter's magnetosphere, according to a new Geophysical Research Letters paper co-authored by Planetary Science Institute Senior Scientist Jeff Morgenthaler. Jian-Zhao Wang of the University of Colorado Boulder is the paper's lead author.

When NASA’s OSIRIS-REx spacecraft delivered pristine samples from the asteroid Bennu back to Earth in 2023, scientists knew they were receiving one of the most chemically untouched collections of material ever recovered from the Solar System.

Since then, the returned grains have steadily transformed researchers’ understanding of how asteroids formed, how water altered primitive worlds, and even how the ingredients for life may have spread through the early Solar System.

Now, a new study, published in Nature Communications, has uncovered another surprise hidden inside those microscopic particles. Embedded within Bennu are tiny mineral fragments that formed during the Solar System’s earliest moments—less than 100,000 years after its birth—and they may reveal that the asteroid’s ancient parent body formed much farther from the Sun than scientists once suspected.

The research suggests that Bennu inherited some of the oldest surviving solids ever created, while simultaneously preserving evidence that Jupiter’s formation may have acted as an enormous cosmic filter, separating different populations of dust before planets had even fully formed.

“Our observations of phyllosilicates replacing olivine and interstitial phyllosilicates between olivine grains within AOAs… collectively indicate that these refractory inclusions experienced aqueous alteration on Bennu’s parent planetesimal,” researchers write. “Therefore, they were incorporated into the parent planetesimal before the onset of aqueous alteration, during which phyllosilicates and magnetite formed.”

“These mineralogical, isotopic, and chronological similarities among refractory inclusions in Bennu samples, Ryugu samples, and CI chondrites provide evidence that their parent planetesimal(s) accreted a common suite, and likely similar relative abundances, of high-temperature refractory inclusions and their fragments,” researchers write.

The research concentrates on “refractory inclusions”—tiny mineral-rich objects known as calcium-aluminum-rich inclusions (CAIs) and amoeboid olivine aggregates (AOAs). These objects are widely considered the oldest solid materials to condense from the hot gas surrounding the newborn Sun.

Long before planets existed, the infant Solar System consisted of a rotating disk of gas coupled with dust known as the protoplanetary disk. Temperatures near the young Sun exceeded 2,000 degrees Fahrenheit (roughly 1,100 degrees Celsius), allowing only the most heat-resistant minerals to crystallize.

These refractory inclusions were among the very first solids to emerge from that environment before eventually being transported throughout the growing Solar System.

Although scientists have found such inclusions in meteorites for decades, Bennu offered an unprecedented opportunity to examine them in material collected directly from an asteroid rather than from meteorites that survived passage through Earth’s atmosphere.

To investigate, researchers analyzed polished sections prepared from 12 Bennu particles using scanning electron microscopy, transmission electron microscopy, oxygen isotope measurements, and radioactive aluminum-magnesium dating techniques.

The team identified six amoeboid olivine aggregates and three calcium-aluminum-rich inclusions, all remarkably small—none exceeding roughly 100 micrometers across, or about the thickness of a human hair. This turned out to be one of the study’s most important discoveries.

The mineral chemistry and oxygen isotopes showed these inclusions formed in an extremely hot, oxygen-16-rich environment during the Solar System’s earliest stages. Radioactive dating using aluminum-26 indicated at least one inclusion formed essentially at the very beginning of Solar System history, within roughly the first 100,000 years after the earliest known solids condensed.

In other words, Bennu contains fragments that have survived for approximately 4.567 billion years with surprisingly little alteration. Yet, those ancient relics also preserve evidence that they later encountered liquid water.

Several inclusions show minerals partially replaced by phyllosilicates—water-bearing clay minerals—while magnetite and other alteration products reveal that water once circulated through Bennu’s ancient parent body after these primordial objects had already become incorporated into it.

For scientists, that sequence helps establish a timeline. First, the earliest high-temperature solids formed close to the newborn Sun. Later, they were transported outward through the protoplanetary disk. Only after they became part of Bennu’s larger parent asteroid did liquid water alter portions of the rock.

Researchers found distinct similarities between Bennu’s inclusions and those previously identified in samples returned from Japan’s Hayabusa2 mission to asteroid Ryugu, as well as in rare CI carbonaceous chondrite meteorites found on Earth.

The oxygen isotopes, crystal chemistry, and formation ages all closely match, suggesting these seemingly distant objects inherited material from the same population of ancient Solar System building blocks.

That mutual heritage points toward a surprisingly interconnected early Solar System, where material formed close to the Sun was efficiently transported across enormous distances before eventually becoming incorporated into multiple asteroid populations.

However,  the absence of something proved just as revealing as what scientists found.

Unlike many carbonaceous meteorites, Bennu contains no large refractory inclusions larger than about one-tenth of a millimeter. Other meteorites frequently preserve inclusions ranging from submillimeter sizes up to several centimeters across.

According to the researchers, the missing population may reflect the increasing influence of the Solar System’s first giant planet.

As proto-Jupiter accumulated mass, its gravity likely created a pressure bump within the gas disk encircling the young Sun. Such pressure bumps act as natural traffic jams for dust, trapping larger particles while allowing much smaller grains to continue drifting through the disk.

Under this scenario, larger refractory inclusions became concentrated closer to Jupiter’s orbit. At the same time, only the smallest particles were able to migrate farther outward into the distant regions where Bennu’s parent body eventually formed.

If correct, Bennu’s microscopic inclusions effectively record the influence of Jupiter before the giant planet had even fully matured.

The hypothesis also helps explain why Bennu, Ryugu, and CI meteorites all possess nearly identical populations of tiny refractory inclusions while lacking the larger varieties commonly found elsewhere.

Rather than showing different source materials, the distinction may instead reflect where—and perhaps when—their parent bodies assembled within the developing protoplanetary disk.

The findings similarly reinforce earlier studies suggesting Bennu is among the Solar System’s most chemically primitive objects. Because large refractory inclusions contain unusually high concentrations of certain elements, their absence helps preserve Bennu’s overall composition close to that of the earliest solar nebula from which the planets formed.

That makes the asteroid an unusually valuable time capsule. Every new microscopic grain examined inside the OSIRIS-REx collection provides another insight into processes that occurred billions of years before Earth existed as a habitable world.

Rather than simply representing rubble from a small asteroid, Bennu appears to preserve a remarkably faithful record of how the Solar System sorted, mixed, transported, and assembled its earliest building materials.

The study also demonstrates why sample-return missions have grown increasingly important to planetary science. Laboratory instruments on Earth can perform measurements impossible for spacecraft operating millions of miles away, letting researchers reconstruct events that occurred within the Solar System’s first fractions of a million years.

“We conclude that Bennu’s parent planetesimal, like those of Ryugu and CI chondrites, accreted small refractory inclusions that persisted in the outer Solar System beyond the influence of the proto-Jupiter-induced pressure bump,” researchers write. “Taken together, these findings highlight the need to integrate Bennu samples into comparative studies of early Solar System solids to better constrain the diversity and possible genetic links among planetesimal formation pathways,” researchers write.

The study, “Refractory inclusions in Bennu samples indicative of outer Solar System accretion,” appeared in Nature Communications.

Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan.  Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com 

Having launched on July 16, 1969, and landed on the Moon on July 20, the Apollo 11 astronauts returned home and splashed down in the Pacific on July 24, 1969. In a historically momentous trip, Neil Armstrong and Buzz Aldrin had become the first people to step onto the Moon. (The third member of theirContinue reading "July 24, 1969: Apollo 11 returns home"

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Scientists have identified four types of black holes, classified mostly by their masses. But these mysterious objects continue to challenge our understanding of the universe.

Astronomers have discovered a remarkably tiny group of six young galaxies just 1.2 billion years after the Big Bang. This may be a rare glimpse of how some of the universe's largest galaxies formed. The paper outlining the findings was submitted to the arXiv preprint server on July 13.

Scientists working at the European Southern Observatory’s Very Large Telescope (ESO’s VLT) in Chile have detected evidence for an unusual, ‘moon-like object’ in the CD-35 2722 system that doesn’t appear to orbit a planet.

The research team behind the discovery said the unusual object, which orbits a brown dwarf that orbits a large, Sun-like star, doesn’t fit normal astronomical categories, leaving them unsure what to name it.

If confirmed, the unusual space object would be the first moon without a host planet ever discovered. Such a confirmation would also make the newly termed “exosatellite” the first exomoon of any type discovered outside our Solar System.

Moon-Like Object Part of ‘Super Weird’ System

According to a statement announcing the moon-like object, ESO student Kevin Hoy had been monitoring the CD-35 2722 star system for months. The measurements that spotted the new, moon-like object were taken with the observatory’s CRIRES+ instrument using the radial velocity method that spotted the first planet around a Sun-like star.

During that time, the researcher and lead author of a study detailing the find said he noticed the system was “super weird” compared to our local Solar System. While the star at the center of the system, with a mass of about half of our Sun, was not unusual, they also determined that it is orbited by a brown dwarf. Brown dwarfs are astronomical objects too small to be a star, but too massive to be a planet, making the pairing unusual. Still, it was not unheard of.

However, according to Hoy, when the team spotted a third, smaller object in the system, they were left confused. Measurements indicated it is at least as massive as Jupiter, suggesting it may be a moon orbiting the Brown Dwarf, only without a host planet.

“The satellite we report is a giant gaseous body orbiting a highly massive companion, itself several times the mass of Jupiter,” explained Alice Zurlo, Director of the Millennium Nucleus of Young Exoplanets and their Moons (YEMS) in Chile project and collaborator on the study.

Mysterious ‘Exosatellite’ Defies Traditional Classification

The team has temporarily named the moon-like object an “exosatellite.” However, Hoy said the object’s status as a ‘third wheel’ in the system makes them want to classify it as a moon, “even if it is nothing like the small, rocky moons we have in our system.”

“This system is somewhat hard to define using Solar-System-based words like ‘planet’ and ‘moon’,” the researcher explained. “The exosatellite is clearly massive enough to be a planet, but it does not orbit a star, though it orbits an object that orbits a star.”

Director Zurlo said the differences between the observed system and our own Solar System have added to the difficulty in labeling the moon-like object.

“We have a clear delineation between the planets and the Sun in the Solar System, so defining things like moons is simple,” Zurlo explained. “In the CD-35 2722 system, where we are blurring the lines between stars, planets, and moons, the whole thing becomes more complicated to describe.”

“This System is Truly Unique and Represents a Breakthrough”

When discussing the significance of the moon-like object, Director Zurlo said detecting satellites in other systems will help researchers better understand the diversity in formation and evolution of planets, moons, and other moon-like objects. The director also noted the historical nature of the detection.

“As exotic as it is, this system is truly unique and represents a breakthrough: the first plausible detection of an exosatellite,” the researcher explained.

Moving forward, the team said the increased sensitivity of the 39-meter mirror on the ESO’s in-development Extremely Large Telescope (ELT) will allow for the detection of even smaller moons, including potentially spotting moons the size of Earth’s largest satellite. The researchers said such detections will likely force the astronomical community to reconsider how planetary objects are labeled, especially those in systems so radically different from our own.

The study “Planetary-mass exosatellite detected around the substellar companion of a star” was published in the journal Nature.

Christopher Plain is a Science Fiction and Fantasy novelist and has spent the last six years as Associate News Editor and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him at christopher@thedebrief.org.

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