Mercury, which is about one-third the size of Earth, may have shrunk more in its evolution than scientists originally thought.
A new study suggests that the tiny planet may have contracted 10% to 30% more than previous models suggested — meaning the planet’s total diameter shrunk almost 12 miles (19 km) since Mercury was formed. (Mercury’s diameter today is roughly 3,032 miles (4,880 km).
Previous missions overlooked the extent of the shrinkage because impact-crater debris on Mercury's surface hid the evidence, according to a study published Thursday (Sept. 10) in the journal Geophysical Research Letters. That size difference is important when researchers consider the planet's history, said Gaku Nishiyama, a planetary scientist at the German Aerospace Center Institute of Space Research and an author of the study.
"Because Mercury's evolution is driven by its cooling, the amount of contraction — an indicator of the extent of cooling — is one of the most important observables that can be compared to models for estimating its evolution scenario," Nishiyama told Live Science in an email.
There could also be implications for the planet's composition. For example, more shrinkage at Mercury could mean the planet would have a larger metal core and fewer light elements, such as silicon, inside that core, according to an American Geophysical Union statement.
"The interior of Mercury would reflect its formation," Nishiyama said, and possibly hint at the innermost part of our solar system. "Therefore, to understand how our solar system has evolved up to now, information that can be extracted from this estimation — such as core composition and initial temperature condition — is critical."
A violent history
Observations from NASA's MESSENGER spacecraft (examples shown here) helped the team build new maps of the planet's shrinkage. (Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)
Mercury and the rest of the solar system planets formed due to the gradual collisions and aggregations of rock and gas upon asteroids and comets. Some of those impacts that created the planets also released a lot of heat. Mercury has been slowly cooling from those ancient impacts, and its interior has been shrinking along the way.
While this kind of cooling affects the entire planet's landscape, impact craters can mask the effects because each crash into the surface generates its own surface changes, including debris and new divots. The craters build up over time, making it difficult to spot more ancient geology underneath.
Nishiyama's team compared two sets of maps from Mercury, using data from NASA's MESSENGER mission, which orbited Mercury between 2011 and 2015. One set of maps charted geological features showing contraction, and the other set estimated the roughness of the planet's surface. Their work covered the entire surface and demonstrated that the most rugged spots on the planet have fewer wrinkles from shrinking. In other words, according to Nishiyama, the debris from more recent impacts is covering up the evidence of shrinking.
Nishiyama said more information will help to confirm the estimate. Such data could come from the European Space Agency's BepiColombo spacecraft, which began its arrival sequence at Mercury earlier this month after nearly eight years of space travel. Once the mission settles in, the spacecraft will take higher-resolution imagery of the surface than MESSENGER did. Nishiyama's team expects BepiColombo to pick up smaller impact craters, as well as scarps and ridges, that could further refine the measurements.
"Stay tuned for future topography measurements by BepiColombo," Nishiyama said. "Future data from laser altimetry on BepiColombo will collect more information on planetary contraction by measuring topography more precisely."
Look up at the night sky and it is easy to imagine a few bright worlds hanging in an empty blackness. But what are we really looking at when we say “the Solar System”? It is a family shaped by one star’s gravity, built from the same ancient disk of gas and dust, and still […]
A brand new observatory began its tenure on Aug. 30 — it's called the Nancy Grace Roman Space Telescope, and it's equipped with a high-tech tool that can directly photograph planets beyond our solar system.
The tool is called a coronagraph; in simple terms, a coronagraph is a device that can be affixed to a telescope and block out the light of a star the telescope is looking at to study features around that star. Without such a device, starlight can be so overpowering that it outshines details nearby. You can think of a coronagraph as a way to recreate a total solar eclipse, except instead of the moon blocking out the sun it's a humanmade mask of sorts that does that trick.
But while coronagraphs have been used many times before, the one that just launched toward the stars is unprecedented. "The Roman Space Telescope is carrying the most advanced coronagraph that humanity has ever put into space," Dominic Benford, the telescope's program scientist, told Space.com.
If you can remember the striking "Pale Blue Dot" image of Earth that NASA's Voyager 1 spacecraft captured while floating about 3.7 billion miles (6 billion kilometers) from the sun, this is the kind of thing scientists expect to see with Roman's coronagraph. A menagerie of Pale Brown Dots should soon make us feel the weight of our existence.
"I love the feeling of smallness that comes from understanding you're not alone in the universe," Vanessa Bailey, Roman's coronagraph instrument scientist, told Space.com.
Earth as a "pale blue dot" seen by Voyager 1 in 1990. (Image credit: NASA/JPL-Caltech)
How does it work?
Coronagraphs aren't really a new thing. Often, they're even used to study our own sun.
For example, NASA's PUNCH mission — which stands for Polarimeter to Unify the Corona and Heliosphere — launched in 2025 and consists of four spacecraft, one of which holds a coronagraph. This coronagraph blocks out the light of our sun in order to reveal the wispy tendrils of the sun's outer atmosphere, or corona.
"In fact, more than 100 years ago, astronomers used coronagraphs to create an artificial eclipse to study the sun's corona," Bailey said during a press briefing on Aug. 29, a day before Roman launched to space. "That's the reason for the name."
But when it comes to other stars, coronagraphs hold another purpose. They can block out a star's light in such a way that planets actually orbiting that star come into view.
"We can block that starlight until we have only a few parts per billion of the light of the star remaining," Benford said of Roman's coronagraph. As a result, he explained, "we can directly see the light bouncing off something like a Jupiter around another star, which we've never been able to do before."
NASA's Solar and Heliospheric Observatory, or SOHO, constantly observes the outer regions of the sun's corona using a coronagraph, which blocks the bright solar disk. (Image credit: ESA/NASA/SOHO)
This process will surely give us our Pale Brown Dots — but to take things a step further, scientists will also be able to dissect the light bouncing off the theoretical Jupiter to reveal what the atmosphere of the world is like, too.
To be clear, Roman isn't the only astronomy tool we have that utilizes a coronagraph while looking beyond our solar system. Even the James Webb Space Telescope and Hubble Space Telescope have their own, for that matter. However, Roman's is far more complex.
For one, the Roman's coronagraph doesn't exactly "block" out starlight like a standard coronagraph does. For the "moon" in its artificial eclipses, it uses a combination of patterned disks and special filters to create destructive interference with the light of a target star. Destructive interference means competing waves of light cancel one another out, leading to a zeroed amplitude. In effect, this blocks out the starlight as necessary and only allows light reflected off the planets of interest to pull through and reflect off the coronagraph's mirrors.
A diagram showing what the disk's pattern might look like. (Image credit: NASA's Goddard Space Flight Center)
The first active coronagraph
Which brings us to the next special part about Roman's coronagraph: It's the first "active" coronagraph to fly in space.
What this means is it can adjust those mirrors in real-time to make sure its exoplanet observations are as clear as possible. This is important because as light reflects off the coronagraph's mirrors, it can create small distortions that mess up the delicate destructive interference dance. You'd need to adjust to bring the balance back, and these adjustments are possible because Roman's coronagraph has hundreds of tiny pistons built into its mirrors. This makes them deformable so they can change shape to account for distortions.
If it all works out, this coronagraph should be capable of detecting exoplanets that are about 100 million times fainter than their stars.
"These deformable mirrors are a real engineering feat," Bailey said during the press briefing. "They can be commanded with the precision approaching the size of an atom, and this is what really allows us to make this transformative performance."
The Roman Space Telescope's coronagraph as scientists were working on it. (Image credit: NASA/JPL-Caltech)
As for what the specific hope is for Roman's coronagraph, Bailey explained there are a few nearby star systems the team is particularly interested in peering into because we have hints of Jupiter-like planets orbiting in those systems that still haven't been imaged. "Or," she said, "there may be really interesting remnants of dust and debris from the process of planet formation." Perhaps that dust could exist in the habitable zones of the stars Roman looks toward, and perhaps this could tell us more about the birth of planet Earth.
"That is interesting in its own regard but also interesting as a precursor to the Habitable Worlds Observatory," Bailey said, in reference to NASA's next great project that will be equipped with a more advanced version of Roman's coronagraph. "We can study how dusty these nearby systems are and understand whether any of them might have too much dust for us to be able to observe an Earth-like planet in the future."
An animation shows what Roman looks like deploying in space. (Image credit: NASA’s Goddard Space Flight Center Conceptual Image Lab)
While Roman will pretty much be focusing on Jupiter-like worlds because they're big enough to be detected with its current capabilities, HWO could certainly find another Earth someday.
From 6,000 exoplanets to 100,000
And before we wrap up, we must briefly mention this newly christened exoplanet hunter's partner tool, the majorly impressive Wide Field Instrument (WFI) that can survey huge swaths of sky in one go. It is because of the partnership between the WFI and its coronagraph that Roman will immensely expand our exoplanet gallery, says associate administrator for NASA's Science Mission Directorate Nicky Fox. The coronagraph won't be finding new exoplanets alone, but rather will be diving deeper into exoplanets the WFI finds first.
The Roman Space Telescope's WFI. (Image credit: NASA/Chris Gunn)
WFI will use two different techniques to contribute to our gallery. The first one is called the transit technique, and it's the same method big names like Kepler and TESS tapped into. It involves noticing dips in starlight that happen when a possible planet transits the face of a star from the telescope's vantage point. "If you see that happen multiple times," Fox said, "you can infer that it's a planet, and you can get the radius and the size of the planet from that observation."
The second technique has to do with gravitational lensing, which refers to how objects with mass in space (and therefore gravitational influence) can warp the very fabric of spacetime and alter the path of light traveling through the affected region. What comes to mind might be a mighty galaxy cluster twisting spacetime like a sheet of satin, but little things like stars and planets can do it, too. The so-called "microlensing" effect of smaller objects warping spacetime leads to the brightening of background objects.
Fox sums up WFI's two techniques in a nutshell: "If you see a little dip, that can suggest there's a transiting planet. You see a little brightening, that can suggest there's a microlensing planet."
For WFI, the microlensing technique will be sensitive to Earth-size planets in the habitable zones of their stars, while the transiting technique will be more sensitive to planets closer to their stars. And as Bailey reminds us, there are absolute heaps of planets to test Roman out on: "When you look up at the night sky, most of those stars have planets."
Right now, we only know of about 6,000 of those worlds. Fox believes this new space telescope could unveil 100,000 more.
Sixty years after television audiences first tuned in to see the voyages of the Starship Enterprise, an astronaut on board the International Space Station has paid tribute to Star Trek by flying the badge of the franchise's latest fictional captain.
Expedition 75 flight engineer Sophie Adenot with European Space Agency (ESA) donned the Delta badge originally worn by actor Anson Mount for a video recorded from aboard the space station. Mount portrays Christoper Pike in the Paramount+ streaming series Star Trek: Strange New Worlds. Paramount and ESA both released the clip on their Instagram feeds.
"For 60 years, Star Trek has brought us stories of friendship and exploration. I'm wearing Captain Pike's badge aboard the ISS in celebration of continuing the real world work of science and exploration," said Adenot. "For me, exploration and science are about curiosity and cooperation daring to go a little farther together, learning from what we discover and build, and turning that knowledge into a better future for everyone."
Sixty years after television audiences first tuned in to see the voyages of the Starship Enterprise, an astronaut on board the International Space Station has paid tribute to Star Trek by flying the badge of the franchise's latest fictional captain.
Expedition 75 flight engineer Sophie Adenot with European Space Agency (ESA) donned the Delta badge originally worn by actor Anson Mount for a video recorded from aboard the space station. Mount portrays Christoper Pike in the Paramount+ streaming series Star Trek: Strange New Worlds. Paramount and ESA both released the clip on their Instagram feeds.
"For 60 years, Star Trek has brought us stories of friendship and exploration. I'm wearing Captain Pike's badge aboard the ISS in celebration of continuing the real world work of science and exploration," said Adenot. "For me, exploration and science are about curiosity and cooperation daring to go a little farther together, learning from what we discover and build, and turning that knowledge into a better future for everyone."
Wouldn’t a free-floating planet eventually cross paths with a star or even a black hole and start revolving around it? YinToronto, Ontario Free-floating planets (FFPs) or rogue planets are bodies that move through space by themselves, not locked into an orbit around a star. While some may have begun as typical planets flung out ofContinue reading "Why aren’t free-floating planets captured when they fly past stars?"
Beyond the solar system, the line between planet and star can get blurry. Astronomers call objects that fall between the size ranges of planets and stars substellar objects. One type of substellar object, called a brown dwarf, forms from collapsing gas clouds like a star, but is not quite massive enough to fuse hydrogen in its core. Some can briefly fuse a heavier form of hydrogen, known as deuterium, in their cores, though never enough to produce starlight. Others are small and cold enough to develop complex atmospheres.
Recently, astronomers discovered a new type of substellar object in a star-forming region of the Milky Way Galaxy called IC 348. Using observational data from the JWST’s Near InfraRed Spectrograph (JWST NIRSpec), they found objects 0.2% to 1.2% the mass of the Sun that float freely like stars but have carbon-containing molecules called hydrocarbons in their atmospheres. Because these objects are smaller than known brown dwarfs and have evidence of hydrocarbons, scientists refer to them as H-type objects.
To investigate what H-type objects are and where they fit within the spectrum of substellar objects, researchers Richard J. Parker and Catarina Alves de Oliveira analyzed survey data on stars and substellar objects in IC 348, then conducted follow-up simulations to uncover how H-type objects formed. The main question they asked was whether H-type objects form from collapsing gas clouds, like brown dwarfs and stars, or develop around host stars before being ejected and drifting freely through space, like planets.
First, they reviewed the observational records of IC 348 obtained with the JWST NIRSpec and the near-IR spectrograph SpeX at the NASA Infrared Telescope Facility. IC 348 has 495 stars and brown dwarfs combined, as well as 9 H-type objects. Estimates for the age of this star-forming region range from either 1 to 3 million years or 5 to 6 million years, depending on how different teams calculated it. From there, Parker and Alves de Oliveira compared where the stars, brown dwarfs, and H-type objects were located within the cluster. They found no unique spatial distribution among the 3 types of objects.
Then, the team simulated the evolution of IC 348 over 10 million years to determine which initial conditions would result in a spatial distribution closest to the survey data. They simulated an initial giant gas cloud and used a mathematical function to distribute its mass among the 495 constituent objects. The researchers then placed a Jupiter-sized planet around each simulated star that was approximately the Sun’s mass to determine whether they could grow and escape their home star and become H-type objects. They also repeated the simulations by placing the Jupiter-sized planets at distances from the Sun similar to those of Earth, Jupiter, and Neptune, and varied the sizes and star densities of the simulated IC 348 regions.
They found that if Jupiter-sized planets orbited their stars at roughly Jupiter’s distance from the Sun, then 5 to 15 of them could escape their stars in a region like IC 348, which would roughly match the number of known H-type objects. However, the escaped planets were distinctly more spread-out than the observed H-type objects, which share a similar spatial distribution with the cluster’s stars and brown dwarfs. Since the simulations did not match the observed distribution, the researchers suggested that these H-type objects are likely a new sub-category of very small brown dwarfs rather than escaped planets.
Although this study favors a brown dwarf origin for H-type objects, the exact details of how they formed remain up for debate. Astronomers still have multiple competing theories about how ordinary brown dwarfs form. Perhaps they are ejected from their gas cloud before fully forming, have their outer layers stripped by radiation from a nearby massive star, or simply form like stars on a slightly smaller scale. Regardless, future researchers will continue to explore this murky area of substellar astronomy.
New Hubble observations have revealed a dramatic, 10-sided jet surrounding Saturn's south pole, and it appears to be evolving before our eyes.
The Hubble Space Telescope recently snapped a high-resolution view of the striking "atmospheric wave," which appears to have begun forming in 2023, archival Hubble images show. Scientists are curious about how this "decagon" popped up so quickly, given that Saturn's other famous multisided wave — a hexagon at the north pole — has been observed on the planet for 40-plus years.
"The question is, why did it suddenly form now when we haven't seen one before?" Amy Simon, a senior scientist at NASA's Goddard Space Flight Center and co-author of a new study describing the observations, said in a statement.
"The northern hexagon has been there every time we've looked for more than 40 years," Simon added. "This feature is different — it appears to be strengthening, giving us the rare opportunity to watch a giant atmospheric pattern develop."
The famous hexagon at Saturn’s north pole. (Image credit: NASA/JPL-Caltech/Space Science Institute)
Scientists can see the wave persisting through several atmospheric layers, which means it extends beyond the cloud tops. The wave is also found in a large jet stream at Saturn. More observations with Hubble and the James Webb Space Telescope (JWST) will be required to see how the wave is generated and what the decagon illustrates about atmospheres in large gas giants like Saturn.
The images were obtained as part of Hubble's Outer Planet Atmospheres Legacy program, which uses some of the telescope's time to image the solar system's outer planets — Jupiter, Saturn, Uranus and Neptune — once a year. The goal is to obtain long-term observations of these worlds, to supplement spacecraft orbiting or flying by.
From Earth's perspective, Saturn is slowly orbiting in its roughly 29-year journey of the sun so that its south pole is visible from our planet, allowing for a good view of the changing decagon. Hubble, in fact, was not the first to see signs of this decagonal shape; it was ground-based observatories that spotted a mysterious undulating band around Saturn’s south pole in 2024.
Agustín Sánchez-Lavega, first author of the study and a researcher in the Department of Applied Physics at the University of the Basque Country, and amateur astronomers Trevor Barry and Jean-Paul Oger first spotted the forming wave. The trio used the university's Planetary Virtual Observatory Laboratory, which brings in observations from around the world, to make the Saturnian discovery.
While more images in 2025 showed the wave starting to move into a decagon structure, Hubble was able to obtain high-resolution images without Earth's atmosphere in the way.
The Cassini spacecraft, which orbited Saturn between 2004 and 2017, didn't see the feature, hinting that it hadn’t started forming yet, according to NASA. "Given Saturn's symmetry in its north-south jet stream system, we have been searching for a counterpart to Saturn's northern hexagon on the south pole in Hubble images since 1990," Sánchez-Lavega said.
Both Hubble and JWST are expected to provide more opportunities to look at the ringed planet's developing decagon in the near future. In the meantime, Saturn isn’t the only solar system planet with perplexing polar features; 2017 images from NASA’s Juno spacecraft showed that Jupiter’s south pole is studded with gigantic, oval-shaped cyclones that echo the chaos of the planet’s famous Great Red Spot.
Searching for Another Earth with the Nancy Grace Roman Space Telescope
In NASA’s mission fact sheet, Roman’s planners pose several questions. These include:
How common are solar systems like our own?
What kinds of planets exist in the cold, outer regions of planetary systems?
What determines the habitability of Earth-like worlds?
Although scientists have used several methods to detect exoplanets, including Earth-like planets, Roman will employ three. These include the transit method, microlensing, and direct imaging. NASA said the combination of approaches will allow mission scientists to conduct a “sweeping search expected to uncover around 100,000 new exoplanets — a staggering leap compared to the nearly 6,200 currently known.”
“It is hoped that Roman will discover thousands of new exoplanets and significantly expand our knowledge of the diversity of planetary systems in our Galaxy,” explained Associate Professor Edita Stonkutė, an astrophysicist at Vilnius University unconnected to the Roman team, in a statement emailed to The Debrief.
Microlensing Can Reveal Earthlike Planets Orbiting Sunlike Stars
Most exoplanets have been detected by the dimming of their host star when they transit between it and Earth, giving the transit method its name. Roman plans to use that same method for most of its larger planetary detections. However, among the expected tens of thousands of transit-method detections, mission planners expect a small but sizeable percentage to come from microlensing.
NASA said the “light-bending” microlensing phenomenon occurs when two distant stars “align closely from our vantage point.” Due to the strength of the nearer star’s gravity, the light from the more distant one is “warped” around the nearer one, essentially focusing it very briefly for a distant observer.
“If the alignment is especially close, the nearer star acts like a cosmic lens, focusing and magnifying light from the background star.” Professor Stonkutė explained. “By analysing these changes, astronomers can determine that the planet exists and estimate its mass and orbital characteristics.”
Critically, Professor Stonkutė also noted that microlensing can occur with objects other than stars, including exoplanets.
“This is Precisely Where Roman Has the Edge”
Using its Wide-Field Array, Roman will monitor hundreds of millions of stars. NASA said the observatory will monitor these target stars for “tiny surges in starlight” that typically signal a microlensing event.
Although the transit method is employed to detect larger exoplanets, NASA noted that microlensing “specializes in finding planets like those in our solar system.” The space agency added that this includes “worlds as lightweight as Mars in their star’s habitable zone or farther out.”
A star’s habitable zone is typically defined as the orbital plane where an exoplanet could sustain liquid water on its surface, a key ingredient for life as we know it.
Professor Stonkutė described microlensing as “particularly valuable” since it can detect planets that are difficult to spot with other planet-hunting methods. The professor said this includes “small Earth-like planets located far from their star.” The Roman team hopes to find “more than 1,000 microlensing planets.”
The professor warned that “most microlensing events cannot be predicted in advance.” As a result, telescopes need to actively scan large areas of the sky to increase the chances of a microlensing detection
“This is precisely where Roman has the edge over other telescopes that have searched for exoplanets using different methods,” the professor added.
A “Stepping Stone” Toward NASA’s Habitable Worlds Observatory Concept
While Roman is tasked with directly imaging exoplanets, finding another Earth around a Sun-like star will still require an indirect detection, most likely from a microlensing event. However, the Roman team notes that their observatory “will provide a crucial stepping stone for NASA’s Habitable Worlds Observatory concept.”
According to the space agency, that “flagship” telescope, still awaiting final approval, “would be designed to photograph Earth-like planets for the first time ever.”
Roman may also be able to scan the atmospheres of planets detected with the transit method. The space agency said Roman “would also look for signs of life called biosignatures by measuring atmospheric gases like oxygen and ozone that could signal the presence of living things.”
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.
Artist’s concept of the Nancy Grace Roman Space Telescope (Credit: NASA).
Welcome to this special edition of The Intelligence Brief… This week, NASA is preparing to launch the Nancy Grace Roman Space Telescope, its next flagship space observatory and a mission poised to transform our understanding of distant worlds and some of the universe’s greatest mysteries. In our analysis, we’ll be looking at 1) how Roman’s powerful Wide Field and Coronagraph instruments will survey the cosmos on an unprecedented scale, 2) how the telescope could discover thousands of new exoplanets—including elusive rogue worlds—and directly image planets around other stars, 3) how Roman will survey more than a billion galaxies in search of new clues about dark matter and dark energy, and 4) why its combination of Hubble-like image quality and an enormously wider field of view could usher in a new era of astronomical discovery.
Quote of the Week
“We are poised at the brink of unfathomable scientific discovery.”
– Julie McEnery, Roman’s senior project scientist at NASA Goddard
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NASA’s Nancy Grace Roman Space Telescope Prepares for Lift-Off
On Sunday morning, NASA will set a new milestone with the launch of the Nancy Grace Roman Space Telescope, setting the course for discoveries that may include new insights into some of the universe’s greatest mysteries.
As NASA’s next flagship space observatory, this powerful new telescope is designed to discover thousands of distant worlds while also probing the lingering mysteries of dark matter and dark energy. Named after Nancy Grace Roman, NASA’s first chief of astronomy and an early advocate for the efforts that led to the launch of the Hubble Space Telescope, the new space observatory bearing her name is poised to offer one of the most detailed views of our universe ever captured.
Scheduled to lift off aboard a SpaceX Falcon Heavy rocket on August 30, 2026, at 7:26 a.m. EDT, the Roman telescope’s mission is comparable in ambition to those of the Hubble and James Webb Space Telescopes, but also very different in many respects. Here’s a look at what to know about this historic mission, what it may help researchers uncover, and why it could set the pace for a range of important scientific advancements in the coming years.
Roman’s Historic Mission to Observe the Cosmos
At the heart of its mission, Roman will offer astronomers a remarkably wide view of the cosmos. Surveying immense portions of the sky, the powerful instruments on board the telescope will capture high-resolution imagery comparable to Hubble at certain optical and infrared wavelengths—imagery that could dramatically reshape scientists’ understanding of both planets and the universe they inhabit.
In terms of the technologies it will carry with it into space, Nancy Grace Roman Space Telescope will rely on two primary instruments: its Wide Field Instrument (WFI) and Coronagraph Instrument. The WFI is equipped with a 300-megapixel near-infrared camera enabling wide-area imaging and spectroscopy, allowing Roman to conduct large-scale surveys with great precision and sensitivity—all of which make it ideal for use in the hunt for dark energy, exoplanets, and other hard-to-spot cosmic phenomena.
Meanwhile, Roman’s Coronagraph Instrument is designed specifically for imaging and studying exoplanets. Equipped for both imaging and spectroscopy, the coronagraph will suppress the overwhelming glare of distant stars, potentially making much fainter planets orbiting nearby visible. According to NASA, Roman’s powerful Coronagraph will be the first instrument deployed on a space observatory to leverage “numerically optimized, precision-fabricated coronagraph masks.”
By suppressing the overwhelming glare of distant stars so that much fainter planets around them become visible, Roman’s Coronagraph could achieve as much as 100 times the performance of existing facilities, offering a promising chance that some of the faintest planets in the cosmos—some as much as a billion times fainter than their host stars—could become visible.
With a little luck, Roman could also break new ground with the first direct imagery of an exoplanet possessing rings. Going beyond its immediate discoveries, the coronagraph will also demonstrate technologies that could eventually be incorporated into future observatories, including NASA’s proposed Habitable Worlds Observatory.
A New Era of Planet Hunting
Presently, astronomers have confirmed roughly 6,000 planets beyond our Solar System. However, once Roman’s mission gets underway, that number could see a dramatic increase.
One of the ways it will achieve such landmark detections will be with the help of gravitational microlensing, which relies on detecting how the gravity of a foreground object can magnify light from a source much farther away. Using microlensing alone, there is a good chance Roman may discover several hundred—but more likely thousands—of planets, which may include worlds small enough that they have eluded previous detection using existing methods.
Along with the planets it discovers, astronomers anticipate that Roman will also find several new additions to the growing catalog of “rogue planets,” mysterious planetary bodies that wander through the cosmos without orbiting a star.
Additionally, NASA says that anywhere from 60,000 to 200,000 additional candidate planets could be revealed through transit observations, though only a fraction of these are expected to be confirmed through additional observations.
Mapping the Dark Universe
Arguably, one of the most significant components of Roman’s mission involves its study of the unseen side of the cosmos: the mysterious phenomena known as dark energy and dark matter.
In search of answers to such mysteries, Roman will soon begin scanning more than a billion galaxies as it maps the structure and evolution of the universe throughout cosmic history, providing data that will at the very least help researchers narrow down the most promising interpretations among a range of competing explanations for dark energy.
Simultaneously, the telescope will probe dark matter, the unseen material whose gravitational effects are currently needed to explain phenomena in our universe that include the motions of galaxies, as well as the evolution of some of the largest structures in the cosmos.
Hubble’s Vision, But at Far Greater Scale
In many ways, what Roman is expected to achieve will be comparable to its predecessor, the Hubble Space Telescope, although at a far greater scale.
At some wavelengths, Roman will be capable of producing images that approach the clarity of Hubble’s iconic views of our universe, all while capturing as much as 100 times more of the sky with each observation. By capturing more of the sky with each image it produces, Roman’s efforts to map the universe could occur at a remarkable pace—perhaps a thousand times faster than those of its predecessor.
A Historic Mission Lifts Off This Sunday
If all goes according to plan, Roman will be launched aboard a SpaceX Falcon Heavy rocket at 7:26 a.m. EDT this Sunday, Aug. 30. NASA will begin live coverage of Roman’s launch on Sunday at 6:20 a.m. Eastern Time, and you can follow the updates online with NASA’s free streaming platforms.
Once it lifts off, Roman will be carried 930,000 miles from Earth to the Sun-Earth Lagrange Point 2 region, which is the same location where the James Webb Space Telescope is currently operating. After it reaches orbit, for the next 90 days, Roman will undergo commissioning, after which science operations are expected to begin sometime in early 2027.
The observatory’s primary mission will last five years, although Roman could potentially remain operational for more than a decade, offering astronomers an unprecedented look at our universe and possibly a few answers to some of the most baffling questions about our universe.
New research suggests that the circumplanetary disk surrounding the exoplanet PDS 70c contains a ring of dense dust, and the conditions within this ring may allow baby moons to form.
The young star PDS 70 has become famous for its protoplanetary disk and its two growing giant planets, PDS 70b and PDS 70c. At least one of these planets is surrounded by a disk of its own; in 2019, researchers using the Atacama Large Millimeter/submillimeter Array (ALMA) reported the first-ever observation of a circumplanetary disk around PDS 70c, and later observations with ALMA brought clearer views of this disk.
There’s still debate over the exact source of the emission detected by ALMA. Does this emission come from dust, and if so, how is the dust distributed? Is the disk optically thick or optically thin? Does the emission even come from dust, or could it instead be free–free emission from unbound electrons navigating a charged-particle maze?
Dust Diagnosis
Yuhito Shibaike (Kagoshima University) and collaborators recently examined the hypothesis that the emission from PDS 70c’s circumplanetary disk arises from dust distributed in an optically thick ring. To test this hypothesis, the team explored two possible dust distributions, which they call “drift” and “ring.” In the drift model, dust grains within the circumplanetary disk migrate inward toward the planet, leaving much of the disk optically thin. Modeling suggests that this migration is typical in protoplanetary disks, and it might be common in circumplanetary disks as well.
Dust and gas surface density for the modeled disks in the drift (orange) and ring (blue) models. Click to enlarge. [Adapted from Shibaike et al. 2026]
In the ring model, the dust grains are concentrated within an optically thick ring at a certain distance from the planet. Simulations suggest that the formation of this type of dust ring is feasible, arising from a localized increase in gas density, outflows, or other causes.
Shibaike and coauthors found that the ring model naturally reproduced the observed spectral energy distribution for a range of reasonable parameters. The drift model, on the other hand, required an unrealistically high dust-to-gas ratio for the material accreted onto the circumplanetary disk from the parent protoplanetary disk to reproduce the observed spectral index.
Future Prospects and Moon-Making Possibilities
Comparison of ALMA observations (colored symbols) and model predictions (colored lines) from the drift (orange) and ring (blue) models. Click to enlarge. [Adapted from Shibaike et al. 2026]
This work demonstrated the feasibility of the dust-ring model, but it didn’t rule out a contribution due to free–free emission from unbound electrons, which has also been proposed to explain the disk’s appearance. The team noted that distinguishing between thermal dust emission and free–free emission is challenging with existing data, as the two sources produce spectral energy distributions with similar shapes.
Luckily, this likely won’t remain a mystery forever: the next-generation Very Large Array, which is anticipated to begin full science operations in the mid-2030s, should be able to resolve the location of the dust within the circumplanetary disk and illuminate the source of emission.
Finally, if the dust surrounding PDS 70c is concentrated within a ring, what does that mean for the possibility of moons forming within the disk? Shibaike and collaborators found that the conditions within the ring likely satisfy the requirements of both the streaming instability and the gravitational instability, which are required for dust grains to clump together and form the rocky building blocks of baby moons. Perhaps the PDS 70 system will one day be the site of not only a circumplanetary disk, but an exomoon as well!
Citation
“Interpreting ALMA Multiwavelength Continuum Observations of PDS 70 c: An Optically Thick Dust Ring in the Circumplanetary Disk,” Yuhito Shibaike et al 2026 ApJL1006 L26. doi:10.3847/2041-8213/ae86f5
Ultra-hot Jupiter WASP-121b is once again puzzling astronomers. New JWST observations have revealed aspects of this superheated planet’s atmosphere that models cannot yet explain.
An Extreme Planet
Among the more than 6,000 known exoplanets, there are many types of worlds that aren’t represented in our solar system. The most exotic and unfamiliar planets might be the ultra-hot Jupiters: giant planets nestled so close to their host stars that they are tidally locked, with temperatures on their permanently starlit sides climbing to thousands of degrees.
WASP-121b, which circles its F-dwarf host star every 30.5 hours, is one of the best-studied ultra-hot Jupiters. Previous work has started to reveal the complexity of its atmosphere, and now, data from JWST have opened a new window onto WASP-121b’s behavior.
New View from JWST
A representation of an exoplanet’s phase curve. Click to enlarge. [ESA]
To learn more about WASP-121b’s atmosphere, Robert C. Frazier (University of Michigan) and collaborators analyzed JWST Near Infrared Imager and Slitless Spectrograph (NIRISS) observations covering more than one full orbit of the planet. These observations allowed them to construct the system’s phase curve, which describes the total amount of emitted and reflected light from the planet and its host star over an entire orbit.
The team used two 3D general circulation models to predict the planet’s atmospheric structure and extract synthetic spectra and phase curves to compare against the JWST observations. Using nine model configurations in total, the team varied several inputs, including sources of atmospheric opacity, sources of atmospheric drag, and assumptions about whether clouds are able to form on the planet’s cooler nightside.
Left with a Mystery
Frazier and collaborators found two aspects of WASP-121b’s phase curve that their models couldn’t explain: the planet emits less light overall than predicted, and the location of its phase-curve offset changes with wavelength.
Modeled phase curves, shown as the flux of the planet divided by the flux of the star, for WASP-121b (colored solid and dotted lines) compared to the best fit to the JWST observations (black line). Click to enlarge. [Frazier et al. 2026]
The models predict, on average, 12–15% more emission from the planet than observed. This discrepancy might be traced back to how the planet’s radius is determined, which is a simple-sounding task that can be deceptively difficult; WASP-121b isn’t perfectly spherical, and its emitting area changes with wavelength, making it challenging to normalize the planet’s radius for use in models.
The phase-curve offset is the difference between a planet’s sub-stellar point (where the star is directly overhead) and the brightest point in the planet’s atmosphere. In general, some degree of offset is expected because planetary winds tend to whisk heat away from the sub-stellar point, placing the brightest point somewhere to the east (usually). For WASP-121b, the offset is unexpectedly small — suggesting a source of drag in the atmosphere that prevents winds from transporting heat away from the sub-stellar point — and it’s larger at shorter wavelengths. This wavelength dependence isn’t predicted by any of the models, and it’s not clear what causes it.
These results demonstrate something remarkable: that our observations of a planet nearly 900 light-years away have become so precise that they’re pushing our already complex models to include more physics — an exceptionally exciting motivation for model improvement!
Citation
“The Days Drag On on WASP-121 b: Interpreting Its NIRISS Spectroscopic Phase Curve with General Circulation Models,” Robert C. Frazier et al 2026 ApJ1004 102. doi:10.3847/1538-4357/ae69ca
Stars do not actually switch their lights on and off when they twinkle. The flicker happens between the star and your eyes, as its light passes through Earth’s moving atmosphere. Planets are affected by the same air, but they usually look steadier because their light arrives from a small disk rather than a single point. […]
Astronomers have found a third giant planet around Beta Pictoris, one of the best-known young planetary systems near Earth. The discovery is striking because the planet was not first picked out as a bright dot in a telescope image. NASA’s James Webb Space Telescope found it in the spectrum of light coming from the system: […]
NASA is currently targeting August 30 for the launch of the Nancy Grace Roman Space Telescope from Florida. The date can move, as launch dates do, but the mission is close enough to the pad that its central idea deserves a clear look: Roman will survey huge stretches of the universe in one exposure, gathering […]
On July 27, technicians at NASA’s Kennedy Space Center in Florida installed a memory card containing 1,350,144 names as part of a commemorative plaque on the Nancy Grace Roman Space Telescope. The names were submitted by people globally, including astronauts from Artemis II and Artemis III. The memory card will travel with the Roman observatory to the Sun-Earth Lagrange point 2, or L2, about one million miles from Earth, where the Sun’s and Earth’s gravity balance out.
Roman is named after Dr. Nancy Grace Roman, NASA’s first chief astronomer and one of the architects of the agency’s modern science program. Roman championed space-based observatories that could study the universe from above Earth’s hazy atmosphere while making their data broadly available to the scientific community.
NASA and SpaceX are targeting launch for no earlier than 7:26 a.m. EDT Sunday, Aug. 30 aboard a SpaceX Falcon Heavy from Launch Complex 39A at Kennedy.
In addition to model development, the Mars Climate Modeling Center (MCMC) conducts cutting-edge scientific research on the past and present atmosphere and climate of Mars.
The Mars Climate Modeling Center (MCMC) conducts atmospheric and climate science research using the NASA Ames Mars Global Climate Models (MGCMs), advancing our understanding of Mars’ climate today, in its ancient past, and as a target for future exploration.
Mars’ climate is governed by three interacting cycles — dust, water, and carbon dioxide (CO₂) — that vary across seasons and from year to year. MCMC scientists use the MGCMs to study these cycles and the processes that drive them, including:
Dust storms and dust transport – Investigating the mechanisms that lift, transport, and remove dust in the Martian atmosphere, including the onset and evolution of regional and global-scale dust storms.
Water and CO₂ cycles – Studying the seasonal exchange of water and CO₂ between the atmosphere, polar caps, and surface, and the clouds that form as a result.
Atmospheric dynamics – Examining circulation patterns, wave-mean flow interactions, and the extension of the MGCM into the middle atmosphere to better connect the lower and upper atmosphere.
Ancient Mars and habitability – Reconstructing past climate states, including the role of asteroid and comet impacts, to assess when and where conditions may have supported liquid water and habitability.
Mission support – Applying model results to landing site selection and characterization, atmospheric entry planning, and interpretation of data from current and past Mars missions.
This research is carried out by a team of civil servant and contractor scientists, postdoctoral researchers, and students, often in collaboration with universities and other NASA centers. You can read more about individual MCMC team members and their science on the Group Members page. A full list of MCMC research papers, conference presentations, and technical reports is available on the Publications page.
This illustration depicts charged particles from a solar storm stripping away charged particles of Mars’ atmosphere, one of the processes of Martian atmosphere loss studied by NASA’s MAVEN mission.
NASA/GSFC
NASA MAVEN (Mars Atmosphere and Volatile Evolution) mission scientists have uncovered a key puzzle piece in understanding certain types of auroras on Mars, finding that they form in a similar way to Earth-based auroras.
Results published Thursday in Nature Communications show the same mechanism that circulates and catapults charged particles into Earth’s atmosphere is happening at Mars on much smaller scales because of differences in the two planets’ magnetic fields.
The MAVEN spacecraft, in orbit around Mars, experienced a loss of signal with ground stations on Earth on Dec. 6, 2025. On June 3, NASA declared the mission had concluded after finding the spacecraft to be unrecoverable. However, data from the mission is still being used to inform NASA science and future missions to Mars.
When the Sun’s magnetic field lines get close to Earth’s magnetosphere, the large magnetic bubble protecting the planet, they can reconnect and inject energy and mass throughout Earth’s magnetosphere and magnetotail, ultimately firing electrons back into the atmosphere to generate Earth’s auroras. This process, called the Dungey cycle, drives electrical currents, accelerates charged particles that create auroras, and controls the circulation of plasma in Earth’s magnetosphere and ionosphere.
This new study shows that a miniature version of the Dungey cycle is happening over Mars’ strong crustal magnetic fields, which gives scientists a better look into the physics of Martian auroras.
“We knew that magnetic reconnection was happening at Mars but did not expect it to be like the Dungey cycle,” said Shaosui Xu, lead author of the study and associate research physicist at the Space Sciences Laboratory at the University of California, Berkeley.
Mars does not have a global magnetic field like Earth. Earth’s magnetic field is created by our planet’s churning core, while Mars has numerous miniature magnetospheres that arise from intensely magnetized crust scattered around the planet. These regions were formed around 4 billion years ago when lava cooled in the presence of Mars’ ancient global magnetic field, which has since disappeared due to intense solar wind stripping the planet’s atmosphere.
The MAVEN mission has observed highly localized auroras over these crustal fields, similar to Earth’s auroras at the poles, but it wasn’t until now that scientists could fully understand the physics of how they form. The study used several instruments aboard the MAVEN spacecraft to build up a picture of the Dungey-like behavior: the Magnetometer and Solar Wind Electron Analyzer instruments, which were used to determine the magnetic configuration and derive electrical currents, and the STATIC (Suprathermal and Thermal Ion Composition) instrument, which was used to measure plasma flows in the ionosphere.
“We really pushed the limit of STATIC to get the data we needed,” said Xu. “It was the final piece to the puzzle in understanding these localized auroras.”
The realization that a Dungey-like cycle was happening within these crustal magnetic fields answered the question of how the electrons were being energized to create the auroras. It also shows that a Dungey-like mechanism can happen on both large and small scales, giving more insight into where in the solar system this process could be taking place.
“This is a remarkable result that changes how we think of Martian auroras and is another important step toward understanding why Mars and Earth have evolved so differently despite being governed by the same underlying physics.” said Shannon Curry, MAVEN’s principal investigator and a research scientist at the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder. “I am incredibly proud of our team’s work on this discovery and excited to uncover new insights into the Red Planet and its evolution.”
By finding out more about this process, scientists also are gaining a better understanding of how the solar environment interacts with the Red Planet as a whole, which is essential for future robotic and crewed missions.
“I remember in graduate school discussing with my advisor how the cycling of crustal magnetic fields could work at Mars,” said Xu. “It’s incredible to be part of the team that found the answer to that question.”
The MAVEN mission is part of NASA’s Mars Exploration Program portfolio. The mission’s principal investigator is based at the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder, which also is responsible for managing science operations and public outreach and communications. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the MAVEN mission. Lockheed Martin Space built the spacecraft and is responsible for mission operations. NASA’s Jet Propulsion Laboratory in Southern California provides navigation and Deep Space Network support.
For more information on NASA’s MAVEN mission, visit:
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