Comet 220P/McNaught has already put on an unexpectedly impressive show this summer as two dramatic outbursts of activity caused it to shine 20,000 times brighter than usual. Here's how you can spot the icy interloper before it fades in the coming weeks.
Comet 220P/McNaught orbits the sun once every 5.5-years. It reached perihelion — its closest point to the sun — on June 14. Solar heating typically increases cometary activity by causing volatile ices to turn directly into gas, releasing dust that reflects sunlight.
The comet's most recent perihelion passage was accompanied by two dramatic outbursts that saw its brightness jump to 20,000 times its usual level, making the ordinarily dim comet temporarily visible to stargazers using binoculars, telescopes, or cameras.
Comet 220P/McNaught is expected to dim significantly as it travels farther away from the sun, though it's possible that another outburst could see its brightness increase once more in the coming weeks!
McNaught's has a current brightness, or magnitude of +9.2 according to the Comet Observation Database run by the Crni Vern observatory. That would make it a challenge to spot with a pair of binoculars under less than perfect conditions, but puts it within reach of small telescopes under dark skies, where it mayappear as a faint, diffuse patch against the background stars.
Where can I find Comet 220P/McNaught in early September?
Look east around midnight local time to find the stars of the constellation Taurus rising into the late summer sky. Next, identify the "V" formation of the Hyades open star cluster shining at the heart of the constellation. Comet McNaught can be found close to the magnitude 3.59 binary star system Omicron Tauri, two stars out from the point of the stellar "V".
How to find Comet McNaught with the stars of the constellation Taurus. (Image credit: Created by Anthony Wood in Canva)
Comet McNaught will become easier to spot in the dark nights surrounding the new moon phase on Sept. 10-11, which will also present a perfect opportunity for . It'll also make for long- exposure photography.
Comet McNaught shines alongside a perseid meteor in a long-composite image by Osama Fathi. (Image credit: Osama Fathi)
Osama Fathi captured a gorgeous photo of Comet McNaught shining in the skies above Egypt as a lone Perseid blazed earthward on Aug. 15.
"I spent nearly two hours imaging the comet and the real surprise came when a meteor crossed very close to it in one frame — a wonderful and unexpected moment," Fathi told Space.com in an email. "Comets are exciting because of their unpredictability and I hope 220P continues to surprise observers with changes in its brightness and activity in the coming weeks."
Comet McNaught's journey through the constellation Cetus between Aug. 6-26. (Image credit: Dan Bartlett.)
Astrophotographer Dan Bartlett, meanwhile, created this breathtakingly detailed mosaic of Comet McNaught's journey through the constellation Cetus as the icy wanderer glowed in the skies over June Lake, California. The mosaic captures the comet's evolution from Aug. 6-26 as its coma and tail transformed in the wake of its Aug. 5 outburst.
Editor's Note: If you would like to share your astrophotography with Space.com's readers, then please send your photo(s), comments, and your name and location to spacephotos@space.com.
The future of a privately backed robotic mission Venus seems about as cloudy as the planet itself at the moment.
Scientists based at the Massachusetts Institute of Technology (MIT) are working with the California-based company Rocket Lab to search for possible signs of life on Venus. The first step in that program is the Rocket Lab Mission to Venus, which will deploy a small, nose cone-like probe crafted to sample the Venusian atmosphere using a device called an autofluorescence nephelometer (AFN).
That AFN can measure individual particles in Venusian clouds, constraining their size, shape and composition in a search for signs of organic molecules.But that undertaking, primarily fueled by private dollars, has been waylaid due to getting a needed booster flight-qualified.
Neutron readiness
"We call ourselves the Morning Star Missions to Venus. The Rocket Lab Mission is the first mission in the series," said Sara Seager, a noted professor of planetary science at MIT.
"Rocket Lab moved the project to the Neutron rocket, and we are awaiting Neutron readiness," Seager told Space.com. Neutron was originally expected to debut in 2024, but it has yet to make its maiden voyage.
That first flight, which will launch from Rocket Lab's Launch Complex 3 on Wallops Island, Virginia, also depends on the successful completion of the vehicle's qualification testing and acceptance program, according to the company.
While Venus probing via private means has been a bit booster-bushwhacked, there has been promising progress with the venture.
An illustration shows Rocket Lab's Photon spacecraft above the clouds of Venus (Image credit: Rocket Lab)
Ready for Venus duty
Rocket Lab is providing the shell for the entry probe. NASA's Ames Research Center developed its heat shield, called the Heatshield for Extreme Entry Environment Technology (HEEET), which consists of woven material that can protect the spacecraft against temperatures up to 4,500 degrees Fahrenheit (2,500 degrees Celsius).
Also ready for Venus duty is the probe's pressure vessel. Seager's team is providing the AFN, along with their ongoing, rigorous science preparation.
NASA transferred the heat shield to Rocket Lab in March 2025. The Venus probe is now resting in Rocket Lab's Long Beach headquarters. A responsive space entrepreneurial firm, Rocket Lab is providing the launch vehicle, the cruise vehicle and the probe for the mission, which carries the instrument from Seager's team. The mission will conduct the first-ever largely privately funded investigation of Venus.
Engineers at NASA's Ames Research Center in California’s Silicon Valley attach the HEET heat shield on the first private spacecraft targeted for Venus. (Image credit: NASA/Brandon Torres Navarrete)
More to explore
Seager and her team aim to launch follow-on missions to Venus, too.
"After the Rocket Lab mission, we aim to send a payload to Venus to identify complex organic molecules," said Seager. "While this goal will not determine if life is present, it will establish that ingredients for life or molecules potentially used by life are present."
Seager and her colleagues have been studying two potential payloads for future missions. One is a laser desorption mass spectrometer, called ORIGIN, which is being built in Bern, Switzerland. A version of this instrument will soon travel to the surface of the moon on a private lander, via NASA's Commercial Lunar Payload Services (CLPS) program.
Furthermore, Seager and her extended team have been developing a 16-foot-wide (5-meter) balloon capable of floating through the skies of Venus for one Earth week. "We are also developing miniature molecular sensors to target specific molecules of interest, including carbon nanotube sensors," she said.
'High hopes'
Paul Byrne is an associate professor of Earth, environmental and planetary sciences at the University of Washington in St. Louis, Missouri.
While the private Venus sojourn is currently in launch limbo, Byrne is bullish about its potential.
"The course of spacecraft exploration of the solar system rarely does run smoothly. Which is to say, we should expect delays, especially for a private mission, a company focused on developing their next class of rocket and a relatively underexplored destination," Byrne told Space.com.
"I continue to have high hopes for this mission, and for its role in demonstrating the role of private enterprise in space exploration," said Byrne, "and I'm keeping my fingers crossed for a successful flight before too long!"
An abode for alien life?
Venus' surface is a scorching-hot hellscape, a planet ravaged by a runaway greenhouse effect. However, Venus has been receiving more and more attention as a potential abode for atmospheric alien life.
Seager and her colleagues suggest that there is mounting evidence that the ingredients for life may exist in the highly acidic clouds that blanket Venus.
In a new study that appears this week in the Proceedings of the National Academy of Sciences, Seager and her team report that, not only can short peptides (short chains of amino acids) remain stable in extremely acidic conditions, they can also fold into shapes that may allow them to have biological functions.
"We really don't know the full extent of what planetary archetypes are out there. We're seeking exoplanets that might be a true Earth twin, but what if they're all Venuses? Our findings definitely open up a whole range of possibilities," Seager said in an Aug. 31 MIT statement.
"If you find life in the clouds of Venus, then you can pretty much assume that life is quite prevalent throughout the universe," said Peter Beck, founder, president and chief executive officer of Rocket Lab.
There are other interplanetary missions on Rocket Lab's radar, including its ideas for a Mars Sample Return mission. And the company already has Mars experience: It built the twin probes for NASA's Escape and Plasma Acceleration and Dynamics Explorers (ESCAPADE) mission, which launched toward the Red Planet atop a Blue Origin New Glenn rocket in November 2025.
Illustration of Rocket Lab's new Neutron rocket in flight. (Image credit: Rocket Lab)
To be confirmed
According to Rocket Lab's website, the initial mission with MIT — which the company calls Venus Life Finder — has a launch date that's in "to be confirmed" status.
Undaunted by delay, Byrne said that Venus continues to surprise — and additional surprises are surely to come.
"Revisiting old data has given us new insight into the planet's clouds, and the hazes found by earlier entry probes might in fact be from cosmic dust," he said. "These and many other discoveries continue to motivate researchers and mission developers, and Rocket Lab's mission is only going to motivate us further!"
A mysterious giant 10-sided pattern of clouds has recently formed around Saturn's south pole, a new study finds.
This newfound "decagon" joins the bizarre colossal hexagon seen for decades at Saturn's north pole. Saturn's hexagon — a cloud pattern about 20,000 miles (32,000 kilometers) wide — was first discovered in 1988 by scientists reviewing data from NASA's Voyager flybys of Saturn in 1980 and 1981. Despite decades of observations, no similar structure was seen anywhere else on Saturn — until now, as scientists have discovered an even larger structure on Saturn.
The newfound decagon is about 104,250 miles (167,820 kilometers) wide, with each of its 10 sides measuring about 10,425 miles (16,782 km) long. "This is a very unusual atmospheric phenomenon that is helping us to advance our understanding of meteorology in general," study lead author Agustin Sanchez-Lavega, a planetary scientist at the University of the Basque Country in Bilbao, Spain, told Space.com. "It tells us that the hexagon is not a unique, singular feature, as was previously thought."
In the new study, researchers investigated recent images of Saturn captured with NASA's Hubble Space Telescope. The way that Saturn's axis is tilted meant that the ringed planet's southern hemisphere was not visible from Earth from 2012 to 2023.
Hubble images from 2023 revealed the decagon to scientists for the first time. "It certainly came as a surprise," Sanchez-Lavega said. Ever since the hexagon was discovered in Saturn's north, he and his colleagues had investigated pictures of Saturn "to see if there was a polygonal formation in the south. And there was no sign of it."
The decagon moves slowly. "It takes about 800 days to complete a rotation about Saturn," Sanchez-Lavega said.
Previous research suggested Saturn's hexagon results from an eastward jet within its atmosphere flowing in a curving path near the ringed planet's north pole. Small perturbations in the jet — the kind one might expect from jostling with other air currents — made it meander into a hexagonal shape.
This colorful space wallpaper from NASA's Cassini mission is the highest-resolution view of the unique six-sided jet stream at Saturn's north pole known as the hexagon. Image obtained on Dec. 10, 2012 and released Dec. 4, 2013. (Image credit: NASA/JPL-Caltech/SSI/Hampton)
Similarly, experiments that Sanchez-Lavega and his colleagues performed with computer simulations of currents in shallow water suggest the decagon formed because of a meandering wave trapped by a curving atmospheric jet. Unlike the hexagon, whose sides and points have remained equally dark for decades, the decagon varies in darkness across its features. This could mean that it may still be evolving.
"We need to understand how the decagon evolves — in other words, whether in the coming years it will become unstable and break up, or conversely, become more stable and robust as solar radiation increases, which will peak at its latitude of around 60 degrees south in 2032," Sanchez-Lavega said.
The scientists also want to gain a more detailed understanding of the three-dimensional structure of the decagon's clouds, hazes, winds and temperatures. This will help them "develop more advanced models of its formation," Sanchez-Lavega said.
The scientists detailed their findings Sept. 2 in the journal Science Advances.
In the four years that the James Webb Space Telescope (JWST) has been making observations of the early universe, it has been delivering one scientific milestone after another. However, the $10 billion telescope has also left astronomers with a massive problem — literally.
The JWST has been routinely spotting supermassive black holes in the early universe that, at hundreds of millions of times the mass of the sun, are too big to have grown to such monstrous sizes before the universe was even 1 billion years old. These cosmic titans are also too massive in comparison to the masses of their small host galaxies, challenging what astronomers know about the relationships between supermassive black holes and their galactic homes that are usually observed in the modern universe.
Now, new research suggests this isn't such a massive problem after all. The team behind this research thinks that it is all a matter of perspective, and that these early supermassive black holes aren't as monstrous as scientists have estimated.
"We estimate masses of roughly one to ten million solar masses, compared with the tens or hundreds of millions previously inferred," team leader Alessandro Trinca of the Italian National Institute for Astrophysics (INAF) Astronomical Observatory of Rome told Space.com. "These are still enormous objects, comparable to the four-million-solar-mass black hole at the center of the Milky Way, or a few times larger, but they lie at the lower end of the supermassive black hole population rather than among the most extreme examples.
"Importantly, these masses are much more consistent with the small galaxies that host them."
The answer to this puzzle may lie in missing X-rays
To reach such sizes, these black holes must be voraciously feeding on surrounding gas and dust. Such feeding black holes and the cosmic larders of gas and dust that surround them are usually extremely bright emitters of X-rays. But this doesn't seem to be the case with the supermassive black holes in the early universe seen by the JWST. The team looked at 14 X-ray-silent supermassive black holes, finding that there is another way of considering this lack of emission.
"Almost none of them are detected in X-rays, even in very deep observations with NASA's Chandra X-ray Observatory," Trinca said. "We interpreted this lack of X-rays as a clue rather than a problem. By incorporating it into our analysis, we find that these objects are likely much less massive than previously estimated. This brings their estimated masses into better agreement with the properties of their host galaxies."
This led Trinca and the team to another conclusion: these early supermassive black holes may not be as massive as previously theorized, but they are feeding even more rapidly than was thought.
An illustration of the region surrounding a feeding supermassive black hole. (Image credit: Robert Lea (created with Canva))
If feeding supermassive black holes blast out a lot of X-rays, then it might seem somewhat counterintuitive that ravenously feeding black holes could be X-ray "quiet."
Trinca explains that this apparent contradiction is related to what happens when a black hole accretes matter at extremely high rates. The disk of gas around the black hole becomes geometrically thick, forming a donut-like structure with a narrow funnel along the rotation axis. The hot inner region that would normally produce strong X-rays becomes surrounded by this thick disk.
"As the X-rays escape, they are repeatedly scattered by the surrounding gas, losing energy before they can emerge. As a result, the black hole appears much fainter in X-rays than we would normally expect," Trinca continued. "Therefore, the lack of X-rays is not unexpected in this scenario; it is actually a prediction of the model.
"In addition, this very high feeding might help explain how these black holes could already have grown to millions of times the sun's mass when the universe was only a few hundred million years old."
Out-eating Eddington
One of the reasons that supermassive black holes are so troubling in the early universe is the fact that they grow by consuming matter and through merging with other black holes. However, there exists a limit to how rapidly a black hole, or any astronomical body, can gather or "accrete" matter.
Called the "Eddington limit," this exists because the more matter a body accretes, the more radiation it blasts out. So as the disk around a feeding black hole gathers enough mass to feed a rapidly growing black hole, it should emit so much radiation that it pushes away more matter, preventing it from being replenished.
Eventually this cuts off the food supply to the black hole and curtails its growth. However, this research suggests that supermassive black holes can enter brief phases of "super-Eddington" feeding.
"If these black holes are up to thirty times less massive than previously estimated, there is much less mass to build up within the available time, and their growth history becomes much less extreme," Trinca said. "Instead of requiring continuous, uninterrupted growth over hundreds of millions of years, the picture becomes one of shorter episodes of very rapid accretion, which is exactly the kind of behavior we might expect in the gas-rich and dynamically active galaxies of the early universe."
An illustration of the JWST which continues to break new ground in astronomy (Image credit: Robert Lea (created with Canva))
Confirming the team's theory about bouts of extreme feeding for supermassive black holes will require astronomical evidence, which may be tough to obtain at least for now.
"The most direct test would be to study similar objects that are accreting very rapidly but are located at lower redshifts, where we can observe and characterize their environments in much greater detail. However, such objects are quite rare," Trinca said. "For the more distant population observed with JWST, future missions providing deeper X-ray observations and improved spectra will be of crucial importance and might potentially detect the weak X-ray emission predicted by this scenario."
The INAF researcher added that in the longer term, obtaining direct and independent measurements of black hole masses at progressively earlier cosmic times will provide the strongest test of the team's theory. For now, the research is a striking example of what scientists can do when they don't detect something, rather than when they make a positive detection.
"What was interesting was seeing how much information could be extracted from something we did not observe," Trinca concluded. "A non-detection may appear to be the least informative type of observation, but in this case the absence of X-rays provided a strong constraint and helped define the physical picture more clearly than the detections alone."
In what could be a groundbreaking discovery, scientists report they may have detected the first direct evidence of dark matter. The potential detection came from the LUX-ZEPLIN experiment, in the form of a single suspected interaction between a Weakly Interacting Massive Particle (WIMP), one of the leading hypothetical particle candidates for dark matter, and an everyday particle.
Dark matter has been a headache for scientists because, despite accounting for 85% of the mass in the universe, scientists have no idea what it is. The fact that dark matter doesn't interact with electromagnetic radiation, or light, means that it can't be composed of electrons, protons, and neutrons, the particles that make up the atoms that compose stars, planets, moons, our bodies, and everything we see around us on a day-to-day basis.
This has spurred on the search for new types of particles beyond the limits of the so-called Standard Model of Particle Physics. So far, this search has been frustratingly fruitless — but the LUX-ZEPLIN experiment may have finally caught a glimpse.
An analysis of data from LUZ-ZEPLIN, a detector composed of 10 tons of ultrapure liquid xenon, one mile underground at the Sanford Underground Research Facility (SURF) in South Dakota, showed a single particle interaction that scientists can't explain with known background signals from normal matter.
"This was a detailed study in a region we hadn't explored within this dataset, and we spent months of additional effort to understand all the possible causes of background events," team leader Sam Eriksen of the University of Bristol in the U.K. said in a statement. "We understand our detector and the backgrounds so well that even a single outstanding event, like the one we found, is important."
What does this tell us about dark matter?
If the event detected by this team was caused by the rare interaction between two WIMPs, this would tell scientists some things about these currently hypothetical particles.
Firstly, the signal indicates that WIMPs have a mass around 200 times greater than the mass of a proton. It also suggests that WIMPs would interact with ordinary matter in a way that hasn't been predicted by the simplest modelling of these particles before.
An illustration of the cylindrical chamber of liquid xenon used by LUX-ZEPLIN to detect interactions between WIMPs. (Image credit: Greg Stewart/SLAC National Accelerator Laboratory)
Of course, these results are not definite yet. This one potential detection isn't statistically significant enough to confirm that what has actually been detected is an interaction between a WIMP and an everyday matter particle. There still remains a 0.5% chance that the event could be explained by known backgrounds.
As LUX-ZEPPLIN continues to gather the largest dataset in dark matter science, the team will determine if this event has grown in significance or if its significance fades.
One definite positive is the fact that WIMP/ matter interactions are so rare that it wouldn't take many detections such as this to confirm the existence of WIMP dark matter, thus solving the puzzle of what the universe's most mysterious stuff actually is composed of.
"We expect dark matter events to be extremely rare, so only a handful could mark the first detection of WIMP dark matter," Eriksen said.
It's now possible to disentangle the sprinkling of supernova dust on the moon from the lunar dirt it is mixed up in, thanks to a new computer model that opens up the moon's surface as a time capsule holding details about the history of supernova explosions near the Earth as our solar system has travelled through space while orbiting the galaxy.
When stars explode as a supernova, they shower space with debris, some of which is in the form of radioactive isotopes traveling at high velocity. Some of these radioisotopes enter the solar system to fall on all the planets and moons, including Earth and its moon. Studies of radioisotopes in deep-sea sediments on Earth, coupled with those found in samples of lunar dirt – what scientists term 'regolith' – brought back by the Apollo missions, point to two recent peaks in supernova activity, 2.3 and 7.3 million years ago.
"I think it's beautiful that the remains of past stars can be used to navigate the vast history of our Earth–moon neighborhood, if we have knowledge of how to read the stardust," said planetary scientist Emily Costello, of the University of Hawaii at Mānoa, in a statement.
However, because of the process of erosion and subduction through plate tectonics, most Earth-bound records of supernova activity in our cosmic neighborhood have been lost and reliable records on Earth only go back about 10 million years. Earth's moon, however, is a different story. Because the moon has no atmosphere, there's no wind or rain erosion, nor are there any plate tectonics. The moon, therefore, should host a record of supernova activity going back 80–100 million years, or even longer.
However, while the moon lacks Earth's style of erosion, it does experience what planetary scientists refer to as 'impact gardening'. This is when impacts of objects ranging in size from microscopic micrometeorites to large asteroids, turns over the regolith, mixing it all up including the radioactive supernova debris.
In order to disentangle all this and work out at what depths various radioisotopes have been mixed down to, Costello's team developed a mathematical model that can decode what treasures lie in the lunar regolith.
"To model impact gardening, we have to balance a complex web of physical mechanisms, including impact compaction, excavation, radioactive decay and space weathering, all operating simultaneously within a single, elegant continuum model," said Costello.
"Our mathematical model treats lunar impact gardening as a competition between forces burying the soil and impacts digging it back up. It also accounts for radioactive decay of the star remnants while mapping exactly when and where new stardust was delivered by episodic supernovae."
Costello's team validated their model by comparing its predictions for the depth-concentration of supernova radioisotopes to what is found in Earth's deep-sea sediments and the Apollo samples.
A close-up of Apollo 17 lunar core sample 73001 being taken out of its drive tube for the first time since it was collected by Apollo astronauts in December 1972 at NASA's Johnson Space Center in Houston. (Image credit: NASA/Robert Markowitz)
"When I first shared my model results, my colleagues were surprised by how well-matched the model and the measurements were," said Costello, "This level of fidelity between empirical observations and a physics model is exciting and remarkable."
Their model accurately predicted the depth-concentration profile of iron-60 found in Apollo regolith samples, as well as heavy elements such as plutonium-244, iodine-129, hafnium-182 and curium-247 that have all been buried over time.
However, the real science will begin when future Artemis astronauts bring back new lunar samples from deeper beneath the surface over the coming years.
"These future samples taken from the moon, when considered in conjunction with our gardening model, could reveal new insights into an untold chapter of supernova history," said Costello. "Understanding the physics of regolith mixing ensures that when future astronauts return deeper cores, we can properly read the scrambled layers to reconstruct the history of our solar system's journey through the galaxy."
Some stars encounter supermassive black holes and live to tell the tale. New research shows why the flares these encounters cause dim over repeated episodes, and it may be down to the way these stars spin and an escaping binary partner that leaves them to be a stellar snack for a black hole.
Some stars are unfortunate enough to encounter the supermassive black holes that sit at the heart of every galaxy, being subjected to immense tidal forces that turn them into a strand of stellar spaghetti, a process called "spaghettification." This plasma pasta wraps around the black hole and is gradually fed to it, with some former star stuff being ejected as near-light-speed jets. These occurrences are called tidal disruption events (TDEs).
However, other stars get a reprieve, passing close enough to a supermassive black hole for the cosmic titan to take a bite and strip off material, but not close enough to be fully destroyed. As the star orbits the supermassive black hole, it takes repeated "bites," with this stellar snacking called a repeating partial tidal disruption event (rpTDE).
Each incident causes a flare of light from the vicinity of the black hole, as would be expected from the brightening seen during a standard TDE. But a strange pattern has emerged in rpTDES; each successive flare can become dimmer. Scientists have struggled to explain this dimming for some time, but finally a team of researchers from Syracuse University may have solved this puzzle.
To reach an answer to black hole flare dimming, the team considered a factor that hadn't been thought of before: the spin of the star itself. This element explained the dimming of black hole flaring and also helped to explain why not all rpTDEs play out the same.
"We were puzzled by this for two years," team leader Ananya Bandopadhyay of Syracuse University said in a statement.
A new spin on stellar snacking
Bandopadhyay and colleagues previously determined that how much material a star loses during repeated rpTDE episodes depends partially on its internal structure, which in turn depends on its mass.
Bandopadhyay compares a low-mass star to a fluffy meringue, which makes it more susceptible to the tidal forces generated by the black hole, allowing more material to be stripped from deeper within the star.
In contrast, a high-mass star has a structure more like an onion. That means that when such a stellar body buzzes a black hole in a rpTDE, its outer layers are stripped, but its core resists the influence of the black hole. Thus, as that outer layer is whittled away, there is less and less material to be stripped away in subsequent episodes.
However, that alone can't fully account for the dimming of flares from four of the ten currently discovered rpTDEs, because of the influence the black hole has on the star as it passes.
An illustration shows flaring from a black hole during a TDE (Image credit: Sophia Dagnello, NRAO/AUI/NSF)
The team's prior work had identified that during rpTDEs, supermassive black holes exert a torque on the passing star that causes the star to spin faster during each passage.
That means even though less material falls to the black hole during each passage, the star returns over shorter and shorter periods of time. That helps keep flaring consistently bright. Thus, a recipe for dimming requires a new ingredient.
Bandopadhyay determined that this element could be a star that was already spinning rapidly before its first encounter with a supermassive black hole.
If a star is already rapidly spinning when it first encounters a black hole, the torque experienced doesn't increase that spin much. And without that increase in spin, there is no shortening of periods between episodes, meaning less and less material being stripped would result in dimming.
Of course, that leaves another question: why would a star be spinning so rapidly in the first place?
Rogue stars could be the answer
The key to this mystery could lie in the fact that most stars don't orbit the centers of their galaxies where supermassive black holes dwell alone, instead existing in binary partnerships.
"It is also extremely difficult to 'bind' a star to a supermassive black hole so tightly that it orbits the black hole in a matter of months, and yet they seem to do so in rpTDEs," team member Eric Coughlin of Syracuse University said.
The loss of a partner star, could cause a stellar body to be tightly bound to a supermassive black hole, completing an orbit once every few months.
An illustration shows a star escaping consumption by a black hole as its binary partner is devoured (Image credit: Robert Lea (created with Canva))
During a process called Hills capture, as a stellar binary orbits a supermassive black hole and the gravitational influence of the black hole rips the binary apart, ejecting one star while capturing the other.
If this stellar binary was particularly tight, with the stars closely orbiting each other, this ejection and capture process could leave the trapped star rapidly spinning on a tight orbit.
"This work demonstrates that each of these peculiarities can be explained by the same underlying phenomenon: the tidal destruction of a binary system and the capture of one of the stars," Coughlin said. "From a theoretical standpoint, this is a major step forward in our understanding of the physics at play in these systems."
The discovery may have implications closer to home too. Though the supermassive black hole of the Milky Way, Sagittarius A* (Sgr A*), isn't currently involved in a rpTDE, it is orbited by many rapid stars. These findings may explain how they came to be there.
New research into the interior of Mars further emphasizes that the Red Planet is a world of two very different halves.
Deep inside the southern hemisphere of Mars, the temperature is up to 750 degrees Fahrenheit (400 degrees Celsius) warmer than beneath the northern hemisphere, deepening the mystery of the strange dichotomy between the Red Planet's flattened north and craggy southern highlands.
"Scientists usually assume that the interiors of planetary bodies are generally spherically symmetric, but this is not necessarily true," said Alexander Berne, formerly of Caltech and now at the University of Arizona, in a statement. Berne is the lead author of a new research paper revealing the discovery of the strange southern hotspot.
Berne and his team went back and looked at archival data from three NASA spacecraft – Mars Global Surveyor, Mars Odyssey and Mars Reconnaissance Orbiter – to look for subtle changes in their orbital velocity that might reflect variations in Mars's gravitational field. Using a technique developed by Berne called 'tidal tomography' that also accounts for the sun's varying gravitational influence on Mars as the Red Planet progresses around its elliptical orbit, he and his team were able to infer a model of the interior structure and temperature of Mars.
How the gravitational field that the various spacecraft experienced changed over time differs substantially from what would be expected were Mars's interior perfectly spherically symmetrical. To explain this difference, the mantle beneath Mars's southern hemisphere must be between 390 and 750 degrees Fahrenheit (200 and 400 degrees Celsius) warmer than the mantle in the north, and indeed it is so warm that it could still be partially molten. This could have repercussions for both Mars's habitability and how long Mars remained volcanically active.
Perhaps we shouldn't be surprised that Mars's interior is different in the south compared to the north, because we already know that its surface is asymmetrical. The north of Mars is characterized by lowland plains, while the planet's crust in the south is on average 15.5 miles (25 kilometers) thicker than in the north and is covered by cratered highlands. The northern lowlands may have once been home to a large ocean.
"The dichotomy that we see between north and south is important to understand because it gives information about processes that may have influenced the hydrology of Mars, including the formation of basins that may have held water," said Caltech's Amirhossein Bagheri, who is the second author of the research.
A bird's-eye view of wind-blown dunes in Kaiser Crater, a 129-mile-wide (207-kilometer-wide) impact basin in Mars' southern highlands. (Image credit: ESA/DLR/FU Berlin)
A hotter southern mantle could also explain some other puzzling discoveries on Mars. NASA's InSight lander, which ended its mission in December 2022 and which had a seismometer on board, found that seismic waves dissipate more quickly in the south, which can be explained by the hotter temperature there. Additionally, magnetic anomalies found in iron-bearing minerals in the south now make more sense.
Today, Mars lacks a global magnetic field, but over four billion years ago it had one. If upwelling from a warmer southern mantle heated the crust in excess of the 'Curie temperature', which is the temperature at which materials lose their inherent magnetic properties and any residual magnetism in them is induced, it could have resulted in creating the mysterious magnetic remnants in the iron-bearing minerals.
"Understanding the interior structure of planetary bodies helps us unravel the processes that shaped their formation and evolution," said Berne, although the origin of Mars's north–south divide is still up in the air. It's not even clear whether the surface differences have the same causes as the interior differences.
A false-color map of the Martian surface showing Hellas Basin, the large, dark blue region below the center, one of the largest identified impact craters both on Mars and within the solar system. It is thought to have formed some 4 billion years ago. (Image credit: ESA/MOLA Science Team)
The leading contender is that it's all the result of an ancient giant impact over four billion years ago and that the northern lowlands are therefore actually an enormous impact basin. By gouging out a huge hole in the north, the impact would have facilitated the release of a lot of internal heat, allowing the northern mantle to cool faster than the south.
Alternatively, the thicker crust in the south could have proven to be an efficient lid, preventing the leaking of much heat from the mantle. This can actually be tested – magma upwelling would have stalled as it encountered the thick, dense crust, creating melt intrusions beneath the surface that could be inferred in higher-resolution gravity data.
These are questions for future missions, but the tidal tomography technique could be employed for other worlds too, from Mercury to the large moons of Jupiter.
"As we get more gravity data, we can determine the three-dimensional intricacies of a planet's interior structure," said Berne. "These inferences in turn give us a blueprint for designing future missions and scientific exploration of these worlds."
The discovery of Mars's thermal anomaly was reported on Aug. 27 in Nature.
CAPE CANAVAREL, Fla. — It was a bright and sunny morning here in Florida when the Nancy Grace Roman Space Telescope lifted off planet Earth against a magical blue sky.
"What a glorious dawn launch," Jackie Townsend, the Roman Space Telescope's project manager, said during a post-launch press conference on Sunday (Aug. 30). "The ride was magnificent — it put us right where we wanted to be. All of the deployments went great."
Roman lifted off on a SpaceX Falcon Heavy rocket right on cue at 7:26 a.m. EDT (1126 GMT), beginning its journey to revolutionize the way we see the universe. It will be able to do this thanks to the two stars of its toolkit, the Wide Field Instrument (WFI) and the Coronagraph Instrument. The former is meant to image extremely wide sections of the cosmos to capture tons of fleeting phenomena that are hard to catch — things like supernovas, fast radio bursts and maybe even colliding neutron stars.
Its uniquely wide view will also help scientists decode the intricacies of dark matter and dark energy while perhaps clearing up some contradictions about our universe that scientists have been scratching their heads over for decades. What's the source of the puzzling "Hubble tension?" Why exactly is the universe expanding the way it is? Are we alone?
Meanwhile, the coronagraph will take direct images of exoplanets and bring us a gallery of "Pale Brown Dots" from beyond our solar system akin to the Voyager spacecraft's priceless "Pale Blue Dot" portrait of Earth.
The Roman Space Telescope lifts off. (Image credit: Chelsea Gohd)
What happens now?
Now that it has lifted off, the Roman Space Telescope will undergo a 90-day commissioning period while traveling to its station in space at the sun-Earth Lagrange Point 2, or L2. This is a gravitationally stable point in space on the side of Earth always opposite the sun; it's a popular location to send telescopes because the orientation allows spacecraft to remain safe from heat while still getting a great view of the universe. Notably, the powerful James Webb Space Telescope (JWST) is also located here.
"Roman will travel nearly 1 million miles away from Earth to Lagrange Point L2 and begin transmitting imagery and data back home that will contribute to world-changing science along with captivating imagery like we see from Hubble and James Webb," NASA administrator Jared Isaacman said during today's press conference. "I have no doubt that Roman will become a household name alongside those great instruments of discovery."
Right after getting off the ground and successfully separating from the spacecraft, Roman started undergoing several typical post-launch procedures — for example, outgassing, referring to the spacecraft releasing any trapped gases once exposed to the vacuum of space, getting "power positive" and plunging to the really cold temperature levels necessary to keep its instruments safe.
A visualization showing what the Roman Space Telescope looks like from the side. (Image credit: NASA Goddard Space Flight Center Scientific Visualization Studio)
The picture-perfect launch today adds to Roman's glowing record of efficiency and performance. This telescope has been in development for over a decade and has an estimated total cost of about $4 billion — but while this may sound like lots of time and money, it's pretty good for a space mission. The JWST, for instance, cost about $10 billion. Roman, in fact, was completed under budget and ahead of schedule. And now, it turns out that even the famously fickle Florida weather couldn't stop this space explorer in its tracks.
"The weather got the memo that Roman is always early," Townsend said.
The Roman Space Telescope's solar arrays. (Image credit: NASA/Jolearra Tshiteya)
What exactly will Roman do?
The Roman Space Telescope is a huge deal for astronomers. First of all, with its WFI, it's meant to process a tremendous amount of data in relatively short periods of time in order to survey gigantic zones of our cosmos. For context, the Hubble Space Telescope has generated about 400 terabytes of data across its 35 or so years of service, while Roman will be generating about 500 terabytes every single year.
"Our main survey will take over a year and be really huge," Julie McEnery, Roman's senior project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, said during a prelaunch conference on Saturday (Aug. 29). "We would need over half a million 4K TVs to fully display the single Roman image on our largest survey."
Roman will also view the universe in the infrared region of the electromagnetic spectrum like the JWST, but with a wide-field, shallow view rather than the JWST's super narrow but deep view. This is a big deal because infrared observations are key for astronomers; they allow us to view objects hidden behind interstellar dust and gas as well as objects in the very (very) distant universe emitting light wavelengths that stretch out from bluer, tight ones into redder, longer ones.
And second of all, Roman's coronagraph is state-of-the-art. It's the first "active" coronagraph to be flown in space, which means it's able to actively adjust itself to enhance its observations. The concept is basically like a solar eclipse; a coronagraph blocks out the glare of a star such that anything around that star can come into focus. And that means exoplanets — specifically large ones for Roman's capabilities. NASA will be using Roman foremost to find Jupiter-like worlds around other stars in the universe.
"If you try to imagine seeing an exoplanet next to a star, it's going to be very challenging," Vanessa Bailey, Roman's coronagraph instrument scientist, said during the prelaunch briefing. "The starlight is going to be overwhelmingly bright. It's like trying to see a firefly next to a lighthouse hundreds of miles away. We can use a technology called a coronagraph inside of our camera to block that lighthouse and see the firefly."
People watch on as the Falcon Heavy's booster returns to Earth. (Image credit: Chelsea Gohd)
But what's special about an active coronagraph like this one is that it can change its hardware to increase the amount of targets it can study. Shawn Domagal-Goldman, the head of NASA's Astrophysics Division, offered an analogy about going to see an optometrist:
"They measured my eyes, they measured my vision, and then they gave me a prescription, which I then mailed in, designed lenses to basically impart the opposite area that my eyes impart," he explained. "What the coronagraph does is, it's basically doing that measurement and then reshaping with deformable mirrors in a fast cadence to correct the vision that the telescope is imparting."
"In 1990 when we launched Hubble, we didn't even know there were exoplanets," Nicky Fox, the associate administrator for NASA's Science Mission Directorate, said during today's briefing. "There will be maybe 100,000 [known ones] at the end of Roman."
'The edge of a precipice'
McEnery described today's launch as a transition point, and said it feels like Roman's technical team is on the "edge of a precipice." Launch experts will now hand the baton to scientists, who will start using the machine they worked so very hard to get to space safely.
"We're just about to set foot off into the unknown," she said. "I'm looking forward to the next few months when we turn things on, figure out how well things work, and actually get to use this observatory, this telescope, these instruments in space, in the environment that it's designed for."
Soon, the science is going to come rolling in, she said: "You know, I have no real good words because it's just so exciting."
Another bit of excitement during today's conference came from U.S. President Donald Trump, who called Isaacman right when Fox was beautifully describing what it's like to say goodbye to Roman, a machine that has without a doubt become a member of her team.
"There is that moment where you think, 'I'm never going to see that spacecraft again,' and get that feeling of 'You know, it's never coming back,"' she said. "I liken it to sending your kids to college. They're going to have great adventures."
When Trump called, Isaacman left the room briefly before returning and putting his phone toward the speaker. "I just want to thank everybody and congratulate you," Trump said. "Boy, it looked beautiful on television."
"I just called Jared to find out: 'Is there anything negative that I should know about? Like, it will never be able to return? Little things like that,'" Trump continued. "He said 'No, it's looking great. It couldn't be better and it was another great successful launch.' Jared's doing a fantastic job. You are doing a fantastic job, and I'm supplying you all that money."
During his first term, however, Trump tried to cancel the Roman Space Telescope.
Jared Isaacman speaking to President Donald Trump during the conference. (Image credit: NASA )
From team Earth to team space
It will be a treat to see the first results that come in from Roman, whether it be a "fuzzy little smudge" of an exoplanet, as Bailey once told me we can expect from the coronagraph, or a sweeping panorama of millions of galaxies that can help us decode the truth about dark matter and dark energy. On that note, the dark universe is a huge point of interest for the Roman team, because the way we're able to study this elusive yet ubiquitous aspect of our cosmos is by watching how dark matter and dark energy affect galaxies across vast spaces. It's therefore important to monitor as many galaxies as we can simultaneously.
But as the Roman team has consistently repeated one particular role Roman will have in space: to be a team member to other space telescopes just the way it's always felt like a part of Fox's team.
NASA's Nancy Grace Roman Space Telescope is encapsulated in the payload fairing of its SpaceX Falcon Heavy rocket. (Image credit: SpaceX)
While Roman has a very wide field of view — far wider than that of the Hubble Space Telescope and James Webb Space Telescope — it doesn't have the same resolution as Hubble or the ability to heavily zoom in on objects in infrared like the JWST can. The goal is to have a fleet of telescopes that can work together to show us the universe in as much detail as possible. Roman will work with Hubble, Webb, and even Europe's Euclid space telescope, the ground-based Rubin Observatory and more. In fact, Euclid's field of view is even bigger than Roman's — but it isn't doing the same surveys that Roman will.
Rubin will create a new 3,200-megapixel image of the southern night sky every 40 seconds for 10 years during its observing time — but it's on the ground in Chile, so its view is somewhat compromised by Earth's atmosphere.
"Roman, Rubin and Euclid, they're siblings. They were all proposed and prioritized at the same time, so the design of each of those observatories has been in the knowledge of knowing what the other ones were doing," McEnery said. "There is a reason that most of Roman's observations are in the Southern Hemisphere, and that's to maximize the overlap with Rubin. We're not competitors. We're stronger together, and we both need each other."
"It's kind of like layering paint on a canvas," Fox said. "You layer the data, and it just really unlocks the secrets of the universe."
Scientists are closer than ever before to confirming that a galaxy known as "Cloud 9" is the first "starless" or "failed" galaxy ever discovered by humanity.
A starless galaxy is one with virtually no stars despite possessing a wealth of gas and dust that would normally serve as the building blocks of stars. The dominant element of a starless galaxy would be dark matter, the mysterious "stuff" that remains effectively invisible because it doesn't interact with light.
Located 14 million light-years away near the spiral galaxy Messier 94 (M94), Cloud 9 is currently the best candidate for a starless galaxy humanity has discovered to date. It contains a vast cloud of hydrogen gas with an estimated mass of 1 million times that of the sun, and dark matter with around 5 million solar masses. Yet, the Hubble Space Telescope discovered in January this year that Cloud 9 emits virtually no starlight.
"But the most striking aspect of our research was the absolute emptiness of the image at the location of Cloud 9. When you look at an image reaching those depths and see nothing where a structure containing a million solar masses of gas should be, it is genuinely remarkable," team leader Ignacio Trujillo of the Instituto de Astrofísica de Canarias, Spain, told Space.com.
"Most objects in the universe leave some trace of light. Cloud 9 does not. That silence is, in its own way, the most compelling result we could have obtained."
On the hunt for a failed galaxy
Trujillo explained that despite having enough raw material to build a small galaxy, Cloud 9 seems to have never formed any significant stellar population.
"That combination — gas but no stars, sitting in a relatively normal environment — makes it one of the most compelling candidates for what theorists call a 'dark' or starless galaxy," Trujillo added. "The concept has been theoretically predicted for decades, but observationally confirmed cases remain elusive.
"The difficulty is obvious: if there are no stars, there is no visible light to detect, and the only way to find such objects is through their gas emission — typically neutral hydrogen observed at radio wavelengths — combined with extremely deep optical imaging to rule out the presence of even a faint stellar component."
A close up of the starless galaxy Cloud 9 (Image credit: Trujillo et al)
Trujillo and colleagues set about investigating Cloud 9 using the HiPERCAM camera on the Gran Telescopio Canarias, the world's largest optical telescope. This led to them obtaining the deepest images ever taken of the Cloud 9 region, approximately ten times deeper than any previous optical imaging of this object. "Honestly, the depth we achieved with HiPERCAM in just 2.36 hours of integration was striking," Trujillo said. What they saw left no questions about the nature of this galaxy.
"The result was clear: we detected absolutely no stellar emission within the region corresponding to the location of Cloud 9," Trujillo said. "Assuming an old, metal-poor stellar population — which would be the hardest kind to detect — we can set an upper limit on the total stellar mass of just 16,000 solar masses.
"Cloud-9 appears to be, within the limits of our observations, genuinely starless."
Why do some galaxies 'fail?'
Though starless galaxies are on the verge of escaping the realms of the purely theoretical thanks to this investigation of Cloud 9, how they form is still something of a puzzle.
However, scientists do have a pretty solid idea of how a galaxy could take shape without birthing stars.
"The leading theoretical explanation involves the ultraviolet background radiation that permeates the universe," Trujillo said. "After the epoch of reionization, this radiation field heats the gas in low-mass dark matter halos to temperatures high enough that the gas cannot cool efficiently and collapse to form stars."
The researcher added that simulations of this period of the cosmos predict that dark matter halos below a certain mass threshold, around 5 billion solar masses, should remain essentially starless.
"Cloud 9 has a halo mass consistent with this regime. In this picture, starless galaxies are not exotic anomalies but a natural and abundant prediction of standard cosmological models," Trujillo explained. "The challenge has simply been finding them."
An illustration of a dark starless galaxy dominated by dark matter and gas. (Image credit: Robert Lea (created with Canva))
As impressive as these results are, the jury is still out on Cloud 9 as a starless galaxy. Further investigation will be needed before scientists can firmly declare they have discovered the first starless galaxy.
"On the stellar side, deeper space-based imaging would be particularly valuable because resolving individual stars avoids many of the problems associated with diffuse-light measurements," Trujillo concluded.
"Hubble has already provided extremely strong evidence, and future facilities such as the James Webb Space Telescope (JWST) could potentially push the search further, although the optimal filters and stellar tracers would need to be carefully chosen."
The team's research is available on the paper repository site arXiv.
