A tentative six-year timing signal suggests a massive companion near the hot star’s habitable zone. The detection remains uncertain.
The post HD 156295’s Pulsations Point to a Possible Giant Planet appeared first on Curiosmos.
Planetesimal wrecks are raging around distant stars. With the Webb and Spitzer Space Telescopes, astronomers are learning what that looks like.
The post Webb and Spitzer Telescopes Explore the Planets That Never Were appeared first on Sky & Telescope.
Orbital simulations identify room for a small world around one of the nearby binary’s stars. Observations have not detected a planet there.
The post 70 Ophiuchi’s Two Suns Leave Room for an Earth-Mass Planet appeared first on Curiosmos.
Using data from the James Webb Space Telescope (JWST), astronomers have unraveled some of the atmospheric secrets of a bizarre, blisteringly hot world that has the consistency of marshmallow.
The extrasolar planet, or exoplanet, under the watchful infrared eye of the JWST, is WASP-17b, located around 1,300 light-years away. The exoplanet has a mass around 0.8 times that of Jupiter, but it is around twice as wide as the solar system's largest planet, giving it a "super-puff" consistency comparable to the Earth-based treat. WASP-17 b is so close to its parent star that it completes an orbit in under four Earth days, with this proximity also making the temperature of this "hot Jupiter" skyrocket.
Given the extreme conditions of this exoplanet, it is little wonder that its atmosphere is pretty unusual too. Using a new technique called transmission strings, a team of scientists mapped the contours of the atmosphere of WASP-17b. They found that the atmosphere is shaped like a ring with prominent "gems" rising from it.
"Planets are temperamental, their atmospheres complex and chaotic," team member Hannah Wakeford of the University of Bristol said in a statement. "The fact that all of these numbers came together and showed us this very structured, dynamical picture of this giant world over 1,000 light-years away was just really exciting."
WASP-17b is so close to its parent star that it is tidally locked, meaning one side permanently faces the star; its dayside is constantly bombarded with stellar radiation. In contrast, the planet also has a cooler nightside, which faces out into space in perpetuity.
By creating incredibly comprehensive 3D views of this exoplanet's atmosphere, researchers found that WASP-17b's atmosphere has a chemical composition and temperature that shift between dayside and nightside according to theory and modelling.
This was possible because the transmission strings technique tracked WASP-17b as it crossed or transited in front of its star, capturing the composition of light around the edge of the planet's atmosphere, or limb, from different angles. This method trumps standard approaches because traditional modelling only maps light as an average across the entire limb.
"Rather than assuming your atmosphere is a circle with the same radius all the way around, our technique allows you to pull out different distances from the center to the edge of the planet," Lili Alderson, of Cornell University, said. "We're able to go around the edge.
"So, we've gone from a ring to understanding where on the ring the gemstones are, so to speak."
The modelling showed just such a "gem," that occurs where hot winds from the planet reach the equator and the nightside of WASP-17b, the atmosphere of the cooler side inflates.
"Theory predicts that the morning and the evening sides should have a strong temperature difference, and WASP-17b fits really nicely in that trend – pretty much bang-on what we thought it would be," Alderson said.
The successful application of the transmission strings method is an exciting step forward in the modelling of the atmospheres of the over 6,000 worlds in NASA's exoplanet catalog.
"This is proof of concept that planets are, in fact, 3D objects, and that, consistently, as they go around their star, what we predict should be happening is happening," Alderson concluded. "To move beyond computational exercises and see it for real is a different matter."
The team's research was published on Wednesday (Oct.14) in the journal Nature Astronomy.
In 3 million years or less, WASP-12b will tumble into its host star. It’s not surprising that the planet will meet its end this way, but it is surprising that it will happen so soon. New work tests a potential explanation for the planet’s rapid orbital decay.
Roughly twice as wide as Jupiter and almost 50% more massive, exoplanet WASP-12b zips around its Sun-like stellar host every 1.09 days at a distance of just 0.023 au (3.4 million kilometers or 2.1 million miles). If placed in our solar system, WASP-12b would easily dethrone Mercury as the nearest planet to the Sun.
Observations show that WASP-12b’s already tiny orbit is shrinking, with each orbital period growing shorter at a rate of 29 milliseconds per year (Earth-year, that is). While we would expect the planet to slowly spiral inward due to tidal interactions with its star, it’s moving several orders of magnitude faster than predicted. The planet’s motion has so far defied all attempts to explain it, and now, a new research article by Caleb Lammers (Princeton University) and collaborators appears to topple yet another hypothesis for WASP-12b’s unexpectedly fast orbital decay.
Previous work has proposed that WASP-12b’s rapidly shrinking orbit is due to obliquity tides, which could come into play if the planet had a nonzero obliquity, or axial tilt. Tidal dissipation generally works to keep close-in giant planets like WASP-12b from having a significant axial tilt. However, if you throw a second planet into the system, the companion can exert a torque that could force WASP-12b to remain tilted. This outside forcing, the hypothesis suggests, changes the orbital, spin, and tilt evolution of WASP-12b and ultimately pushes it toward its star far faster than expected without the tilt or the companion.
Constraints on the mass and orbital distance of the companion planet in the obliquity-tide scenario. The color shows the radial velocity signal associated with each combination of parameters. The green line shows the maximum radial velocity allowed by observations. Click to enlarge. [Lammers et al. 2026]
This companion mass and orbital distance are both larger than predicted by previous work, which had suggested that a 10–20-Earth-mass planet at 0.04 au would be sufficient to drive WASP-12b’s inward journey. Lammers and coauthors analyzed WASP-12’s radial velocity data for evidence of such a planet tugging on the star, but found none; only under extremely particular conditions could such a planet exist and not be detected in current data.
Radial velocity constraints on the properties of a hypothetical second planet in the WASP-12 system, obtained via injection-recovery tests. [Lammers et al. 2026]
“The Mysterious Inspiral of WASP-12 b: Why Obliquity Tides Cannot Drive Orbital Decay,” Caleb Lammers et al 2026 ApJL 1009 L43. doi:10.3847/2041-8213/aea405
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Isaac Newton suspected that the gravitational dance between the Sun and Jupiter would eventually destabilize the solar system, but modern computational research has shown that its long-term stability is, statistically, pretty secure. However, new simulations with more realistic solar mass-loss conditions make a strong case for the disassembly of the outer solar system — and on timescales much shorter than previously thought.
Final outer planet orbital configurations for two simulations — one stable and one unstable. t=0 at the onset of white dwarf formation. Click to enlarge. [Adapted from Batygin et al. 2026]
However, all of these studies modeled solar mass loss as a smooth function, so the dismantling of the solar system was left up to external forcings. In reality, stars on the red giant branch undergo mass ejections that are random in time and direction, corresponding to velocity “kicks” that can alter the dynamics of the planets.
A team led by Konstantin Batygin at the California Institute of Technology conducted numerical experiments to analyze the orbital dynamics of the outer solar system under different solar mass-loss conditions. First, they tested the classic case of smooth mass loss and validated previous findings that, despite planetary orbits doubling in size, the dynamics are pretty tame. This holds true even when mass is ejected anisotropically: if the timing is smooth, the asymmetries cancel out.
Next, they simulated stochastic kicks and found that the behavior of the outer planets was largely tied to the ejection mass of each kick. For very small ejection masses (≤ 10-7 M☉), dynamics mimic the smooth mass-loss case. For intermediate values (10-7 to 10-6 M☉), there’s a roughly 20% chance Jupiter–Saturn and Uranus–Neptune enter mean-motion resonances: an orbital configuration where planets’ periods are a ratio of small integers. These resonant configurations don’t protect the giant planets, however: resonant simulations disassemble slightly more often than nonresonant simulations. For larger ejection masses (≥ 10-5 M☉), the outer solar system disassembles on the timescale of billions of years.
Instability onset time — or how long after white dwarf formation the outer solar system disassembles — as a function of ejection mass. The larger the ejection mass, the greater the chance of instability. Click to enlarge. [Batygin et al. 2026]
This new discovery reduces the life expectancy of the solar system from one billion billion years to a meager one billion years after white dwarf formation.
“Terminal Instability of the Solar System Triggered by Stochastic Solar Mass Loss,” Konstantin Batygin et al 2026 ApJL 1009 L22. doi:10.3847/2041-8213/aea290
The post The Solar System Has a New Life Expectancy, and It’s a Billion Times Shorter appeared first on AAS Nova.
By observing subtle variations in the timing of stellar pulsation modes, researchers may have made the first detection of a planet in the habitable zone of a massive A-type star.
To date, some 6,000 exoplanets have been detected across a vast array of surveys and instruments. The majority of these have been detected around main-sequence F, G, and K stars — but not because these are the only places exoplanets can exist. Rather, this is a result of selection bias: these stars tend to be both bright and luminously stable enough for astronomers to deploy the radial velocity or transit methods.
Periodic modulations in the time of observed stellar pulsations can indicate the presence of an orbiting companion. In this case, timing variations are displayed for the two most prominent pulsation modes f1 and f2 for the variable star HD 156295. The sinusoidal pattern indicates they may be caused by an orbiting companion with a mass of about 6.3 Jupiter masses at a distance of 3.9 au, in this star’s habitable zone. [Adapted from Wilson et al. 2026]
Luckily, one transit astronomer’s trash data can be a pulsation timer’s treasure. For some A-type stars called δ Scuti stars, the pulsation is regular enough to be used like a cosmic clock. Subtle variations in a star’s position due to the tug of an orbiting companion can then disrupt the timing of its otherwise steady pulsation, allowing one to once again find planets via its light curve — including massive ones on intermediate-period orbits that are the most difficult to detect around massive stars using traditional methods.
In a new study led by Logan Wilson (Center for Astrophysics | Harvard & Smithsonian), researchers analyzed 16,440 highly pulsating δ Scuti stars observed at a high cadence by the Transiting Exoplanet Survey Satellite (TESS) in order to look for the distinctive, periodic timing modulations associated with an orbiting companion. This sample was then whittled down to nine candidate systems they believe may contain substellar companions — likely either brown dwarfs or massive planets.
The properties of the nine candidate objects identified in this study and their host stars are shown here, along with the properties of other exoplanet systems. Through stellar pulsation timing, the researchers were able to identify substellar candidates around hot A-type stars in intermediate-period orbits, a region of parameter space that has been difficult to probe with other methods. [Wilson et al. 2026]
The other eight candidates are more consistent with brown dwarfs. Six of these candidates show somewhat uncommon masses and orbital separations that place them in a region of parameter space known as the “brown dwarf desert.” Some observations suggest this desert is less severe around hotter stars — a conclusion that this study supports.
All of these findings are still quite tentative, however; the researchers estimate that the probability for the planetary signal being real is just over 50%, and the parameters given for each candidate are still subject to large uncertainties. With new data arriving all the time, it may not take long before we have a clearer picture of these unique substellar companions.
“A Search for Substellar Companions around A-type Stars: Pulsation Timing Detection of Eight Brown Dwarf Candidates and a Possible Habitable-zone Planet,” Logan G. Wilson et al 2026 ApJ 1009 78. doi:10.3847/1538-4357/ae93a0
The post Stellar Pulsations Suggest Habitable-Zone Planet Around a Massive Star appeared first on AAS Nova.
ESA’s Jupiter Icy Moons Explorer returned to Earth on 28 September 2026, but home was only a waypoint. During a successful flyby 8,640 kilometres above the Indian Ocean, Earth’s motion and gravity deflected Juice’s path by 20 degrees and increased its speed relative to the Sun by 3.5 kilometres per second.
The encounter was the third of four planned gravity assists. It followed the first lunar-Earth double flyby in 2024 and a Venus flyby in August 2025. One more Earth pass in January 2029 will finally place Juice on its transfer towards Jupiter, where it is due to arrive in July 2031.
The mission turned this return into more than a trajectory correction. Juice’s navigation camera pointed at the Moon’s horizon to test a technique intended to improve optical navigation during selected encounters in a sequence of 35 future flybys of Ganymede, Callisto and Europa.
The Moon is not part of the gravity assist this time. It is a known target on which engineers can rehearse the image geometry they will later need around worlds hundreds of millions of kilometres away.
The route looks inefficient only if distance is the sole measure. A direct flight would require a much more energetic launch and an enormous propellant load, first to reach Jupiter and then to prevent a nearly 6,000-kilogram spacecraft from flying straight past it.
A gravity assist avoids carrying most of that fuel. In the Sun’s frame, a spacecraft exchanges a minute amount of momentum with a moving planet as gravity curves its trajectory. The result can be a gain or loss of heliocentric speed, depending on the direction of approach. The planet’s own motion is what makes the encounter more than a simple U-turn.
Juice’s first assist in August 2024 deliberately removed energy. The Moon increased its speed by 0.9 kilometres per second relative to the Sun, positioning it for Earth one day later. Earth then reduced its heliocentric speed by 4.8 kilometres per second; overall, the lunar-Earth sequence turned the path by about 100 degrees.
That world-first lunar-Earth sequence sent Juice inward towards Venus while saving an estimated 100 to 150 kilograms of propellant. SpaceDaily’s account of the completed trajectory reset described how the two encounters worked together.
Venus supplied the next turn on 31 August 2025, bending the solar orbit back towards Earth and adding speed. The flyby had no sightseeing component. Juice was built for the cold outer Solar System, so it pointed its 2.5-metre high-gain antenna towards the Sun as a heat shield and kept its remote-sensing instruments inactive.
The operation followed a communications failure caused by a software timing bug that left a signal amplifier switched off. SpaceDaily covered the recovery and final preparation for the Venus encounter. ESA subsequently described the spacecraft as successfully through that flyby and on course for Earth.
According to ESA’s flyby report, closest approach occurred over the Indian Ocean at 11:45 UTC on 28 September. Earth deflected Juice’s trajectory by 20 degrees and increased its speed relative to the Sun by 3.5 kilometres per second.
Those numbers are not produced by an engine burn at perigee. They are the consequence of entering Earth’s moving gravitational field along a carefully chosen line and leaving it in a new direction. A mistimed arrival would change both the size and direction of the result.
The navigation campaign began on 17 August. Six correction opportunities were reserved at intervals including four weeks, two weeks, one week and three days before the encounter. ESA reported after the flyby that only one small manoeuvre had been required; enhanced tracking continues until 10 October.
The reserved final emergency manoeuvre was not needed. Juice passed above Australia before closest approach and then swept over the Indian Ocean along the planned trajectory.
This boost still does not send Juice straight to Jupiter. Jupiter is not yet in the right place. The 2026 encounter has shaped another solar orbit, returning Juice to Earth in January 2029 for the final push onto a path that intercepts Jupiter in July 2031.
Before closest approach, Juice spent eight hours and 39 minutes in Earth’s shadow, from 19:24 UTC on 27 September until 04:03 UTC on 28 September. With no sunlight reaching its solar arrays, the spacecraft operated from batteries alone.
That eclipse did not threaten the flyby, but it limited how freely the payload could be used. Teams prioritised the most valuable observations during the battery-powered interval rather than switching on every instrument continuously.
Across a wider window from 23 September to 3 October, all ten science instruments were scheduled to gather data on Earth and the Moon, though not continuously or all at once. ESA expects to publish selected images and spectra after the data reach Earth and are evaluated. Both bodies are useful calibration targets because their shapes, surfaces and surrounding environment are already measured far better than the Jovian system.
Juice also spent several days inside Earth’s magnetotail, the long nightside extension of the magnetic field shaped by the solar wind. The measurements can test particle and field instruments in a complex but comparatively familiar plasma environment before they face Jupiter’s larger, faster-rotating and more intense magnetosphere.
Two small monitoring cameras photographed the passage as well. They should not be confused with NavCam or the JANUS science camera. The monitoring cameras provide engineering views of the spacecraft and its surroundings; NavCam extracts geometry; JANUS is designed for scientific imaging. NavCam also returned an image of Madagascar taken two minutes after closest approach.
During this Earth approach, the navigation camera pointed towards the lunar horizon, also called the limb. An image of that curved boundary contains information about the apparent centre and angular size of the Moon. Compared with a predicted view, it can sharpen the estimate of the spacecraft’s position relative to the target.
ESA said the lunar observations were intended to test a technique for improving optical-navigation accuracy, but had not published an evaluated performance result at the time of this update. The careful claim is therefore that Moon-limb images tested the method, not that the September campaign has already proved a specific performance gain.
NavCam first operated on a real world during the 2024 lunar-Earth encounter. In its account of that first in-space test, ESA showed raw, uncalibrated lunar images and explained that the camera would later use the shapes of Jupiter’s moons to support navigation.
The 2026 geometry was different. Juice did not fly close to the Moon, and lunar gravity was not the manoeuvre. The Moon was observed from the Earth-approach trajectory as a reference object. Calling it a rehearsal is accurate; calling this another lunar gravity assist would not be.
Ground-based radio tracking remains essential, but a complete Earth communications loop is too slow for fresh local relative-position updates during a close Jovian flyby. Near Jupiter, a radio message can take roughly 50 minutes each way. The location of the moon relative to the approaching spacecraft also matters more than an absolute position measured in isolation.
SpaceDaily’s earlier account of Juice’s image-based navigation system described onboard software that detects the edges of a moon in NavCam images. Those edge measurements allow the system to refine relative geometry without waiting through the complete Earth communications loop.
The underlying system is called Enhanced Attitude Guidance through Limb Extraction, or EAGLE. It is intended for use on the inbound leg of selected moon encounters, with mission planners deciding case by case when the technique should support guidance and pointing.
This does not mean Juice will improvise a tour or replace its flight-dynamics team. Ground controllers design and command the encounters. Optical navigation supplies a timely local measurement during sequences in which a small targeting error could move an instrument footprint by many kilometres or turn a planned close pass into a miss.
NavCam is also not a substitute for the science payload. It is a wide-field engineering camera optimised to tell the spacecraft where a world is. Scientific cameras and spectrometers ask what that world is made of and how its surface changes. A blurred-looking limb can still be excellent navigation data.
After Jupiter arrival, Juice will make 35 flybys of Ganymede, Callisto and Europa before entering orbit around Ganymede in 2034. Each encounter must satisfy navigation, power, communications, radiation and instrument-pointing constraints at the same time.
SpaceDaily has also reported an engineering-model rehearsal of a Callisto flyby, in which simulated images were projected into a navigation camera to exercise the flight software. That laboratory test supplied a synthetic moon; September’s observation supplied a real horizon to the flight camera in space.
Earth and the Moon offer known targets, stronger communications and time to improve procedures. At Jupiter, the encounters will be distant, fast and scientifically scarce. The apparent detour through Venus has preserved the fuel needed to conduct that tour, while the lunar images supplied something equally valuable: a navigation method tested before the real icy moons fill the camera. ESA had not yet released the evaluated performance result, so the size of any improvement remains unreported.
The post To reach Jupiter, Juice took a detour past Venus, then returned to Earth on 28 September for a successful gravity boost while using our Moon to rehearse the navigation it will need around Jupiter’s icy moons. appeared first on Space Daily.
While our solar system sports one Jupiter-like planet, exoplanet discoveries have revealed that giant planets come in a few different forms in systems with varying architectures. A recent study has explored how the mass–eccentricity relationship in warm Jupiters is shaped by dynamical interactions between planets.
Exoplanet surveys have uncovered three different Jupiter-like planet populations across the galaxy: hot, warm, and cold Jupiters. Much like our own, cold Jupiters orbit on long periods, far away from their host stars. Conversely, hot Jupiters zip around their host stars on extremely short-period orbits. Somewhere in between, warm Jupiters orbit their host stars with periods from 10 to 365 days.
Diagram showing examples of a circular and an eccentric orbit. Click to enlarge. [AAS Nova/Lexi Gault]
Does this relationship extend to shorter-period giant planets as well? Hot Jupiters are heavily impacted by tidal interactions with their host stars, circularizing their orbits and erasing dynamical imprints on their eccentricities. Warm Jupiters, on the other hand, orbit far enough away for their eccentricities to preserve clues about their energetic histories. Recently, thanks to the Transiting Exoplanet Survey Satellite (TESS), astronomers have identified a positive correlation between planetary mass and eccentricity in a growing sample of warm Jupiters, but the exact driver of this trend has yet to be uncovered.
To test if the positive mass–eccentricity correlation in warm Jupiters is consistent with planet–planet scattering, Jiayin Dong (University of Illinois at Urbana-Champaign) constructed a sample of 85 warm Jupiters from the NASA Exoplanet Archive. This carefully selected sample, dominated by discoveries from TESS and Kepler, included planets with masses between 0.3 and 15 Jupiter masses and orbital periods between 10 and 365 days. In conjunction with this sample, the authors built a planet–planet scattering framework to assess the range of properties anticipated for scattered warm Jupiter systems.
Warm Jupiter eccentricity versus planet–star mass ratio (left) and semimajor axis (right). Click to enlarge. [Dong et al 2026]
The mass–eccentricity relation of warm Jupiters, the authors suggested, represents a transition from collision-dominated interactions among low-mass planets to ejection-dominated interactions among high-mass planets. For massive enough systems, scattering can excite eccentricities high enough to trigger the high-eccentricity migration responsible for moving hot Jupiters to their close-in orbits. Overall, this study suggests that warm Jupiters are not a distinct planet species, but instead may represent the shorter-period counterparts of cold Jupiters whose orbits are shaped by the same dynamical processes. Future observations expanding the sample of warm Jupiters and discoveries of additional planet companions will further uncover the links between hot, warm, and cold Jupiter systems.
“Planet–Planet Scattering Explains the Mass–Eccentricity Relation of Warm Jupiters,” Jiayin Dong et al 2026 ApJL 1007 L29. doi:10.3847/2041-8213/ae930e
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A cosmic Quarter-Pounder is providing us with a near-perfect view of a distant gas giant’s earliest moments. Known as Gomez’s Hamburger (or GoHam for short), the massive protoplanetary disk surrounds a young star located in the Scorpius-Centaurus stellar region of our home galaxy about 453 light-years away from Earth. As researchers explained in a study recently published in The Astrophysical Journal, GoHam’s vantage from Earth is virtually unparalleled for anyone hoping to glimpse the subtle layers of dust and particles that will one day coalesce into a humongous gas giant.
Early observers first spotted GoHam in 1985, but initially pegged it for a planetary nebula as far as 6,500 light-years from Earth. Astronomers have since revised their assessments with data gathered by the Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile. As its full name implies, ALMA measures millimeter-and-smaller wavelengths, allowing scientists to map the miniscule dust grains and gaseous molecules that compose distant objects. GoHam is a particularly unique subject for ALMA, because its position makes it a new benchmark example for testing models of how planets evolve.
“GoHam gives us a rare and clear view of the vertical and radial structure of a very large, nearly edge‑on disk,” explained study co-author and University of Minnesota astronomer Charles Law.
According to Law, its mixture of cosmic winds, large formational asymmetries, massive disk size, as well as the potential for planetary formation makes GoHam a “perfect laboratory.” With ALMA, Law and his colleagues analyzed GoHam’s layers of carbon monoxide, and sulfur-bearing molecules. As predicted, the lightest gas is in the highest layer above the formation’s midplane, while the heavier sulfur components lay beneath it. Meanwhile, a thin but concentrated section of millimeter dust is visible in the midplane itself.
Comparisons to GoHam’s fast food namesake only go so far, however. Its dust clouds lean north–south, with one side containing brighter and wider emissions. This likely stems from a disturbance such as a cosmic vortex, which may capture additional material for planetary formation. Dim, thin carbon monoxide emissions along the disk’s northern section also suggest GoHam’s central star is blowing gases into deep space as what’s known as photoevaporative wind.
Astronomers also noted that GoHam is one of the largest protoplanetary disks ever observed. At nearly 93 billion miles wide and with an exponentially larger dust mass than the typical protoplanet disk, GoHam may ultimately host not just one gas giant, but an entire planetary system.
The post Distant space ‘hamburger’ hides a baby gas giant appeared first on Popular Science.
The NASA Exoplanet Exploration Program (ExEP) has a curated list of 164 nearest Sun-like stars that are easily visible from Earth. This list represents the first targets for a proposed large space telescope specially designed to find life in the universe, currently known as the Habitable Worlds Observatory (HWO).
After the HWO is completed, likely sometime in the 2040s, scientists will use the specialized telescope to directly image planets in those star systems. The telescope will search around Sun-like stars for planets in a region known as the habitable zone, where temperatures allow liquid water to exist. Scientists hope to find Earth-like planets with liquid water in the habitable zones of other stars.
While the 164 stars on ExEP’s list have qualities that make them good candidates for study, it remains unknown how many actually have terrestrial planets within their habitable zones. A team of scientists at Arizona State University used simulated data for ExEP’s 164 stars and their hypothetical planetary systems to assess which are most likely to have habitable worlds. Their results would help the HWO prioritize which star systems to observe.
The team started with a subset of 134 stars on ExEP’s list with no known exoplanets, giving researchers the freedom to simulate potential worlds around them. They used a software model called the DYNAmical Multi-planet Injection TEster (DYNAMITE) to predict the possibility that an unseen planet exists around each star by generating 100,000 simulated planetary systems around it. The simulations use mathematical formulas based on observations of real exoplanets to determine the sizes and orbital characteristics of hypothetical gas giants and rocky exoplanets. DYNAMITE then determines whether these planetary systems would be stable and include a terrestrial exoplanet in the star’s habitable zone.
The other 30 stars in the ExEP’s list have known exoplanets, but none of them are rocky planets in habitable zones. To predict whether these stars have unseen terrestrial planets in their habitable zones, the team used the same DYNAMITE process as before with the additional requirement that each star must have an exoplanet matching the one already found.
The space around a Sun-like star can be divided into three regions. The region closest to the star is too hot for liquid water to persist on an exoplanet’s surface, while the region farthest from the star is so cold that any water on an exoplanet would be frozen solid. Between these lies the habitable zone, where temperatures would allow liquid water to exist. However, it’s also possible that a combination of light and gravity could create habitable temperatures on large enough moons orbiting gas giants even beyond a star’s main habitable zone. Illustration by Andrew Bizal.
To increase the chances of finding a terrestrial planet in a habitable zone, the team also investigated potentially habitable moons orbiting gas giants in these systems. For each simulation that included a gas giant, the team inserted between 2 and 23 moons, with masses between 10% of Earth’s Moon and 50% of Earth. Then they simulated the surface temperatures of these moons based on how much starlight they receive and how strongly their host planet pulls on them. They deemed the moons potentially habitable if they were large enough to retain an atmosphere and had a temperature ideal for liquid water, even if they were not technically in their stars’ habitable zones.
For each star, the team calculated a metric based on the probabilities that the star had a terrestrial planet in its habitable zone, that the planet would remain in a stable habitable zone for at least 2 billion years, and that the star had a potentially habitable moon. They called this probability statistic a ranking metric and used it to compare star systems.
Based on the ranking metric, the team found that the dimmer and cooler stars on their list generally had better chances of hosting a habitable-zone terrestrial planet than the brighter, hotter stars. They also found that stars without known exoplanets ranked more favorably. Around 70% of the stars with known exoplanets had less than a 1% probability of hosting a terrestrial planet in their respective habitable zones. Additionally, fewer than 0.1% of their simulated moons were habitable.
Overall, the researchers concluded that the HWO should prioritize observing cooler, Sun-like stars with no known exoplanets. They claimed that the exoplanets with known characteristics in their sample set were of sizes and in positions that made it unlikely for other exoplanets to be in their systems’ habitable zones. Even with expanded habitability criteria for moons, it would be very unlikely for HWO to find another Earth orbiting a gas-giant exoplanet. They ranked 47 stars in the highest-priority category (A Tier), 51 stars in the middle category (B Tier), and 66 stars in the lowest category (C Tier) to observe with HWO.
At the end of their study, the team remarked that the proposed HWO represents a potential next step in the search for other Earths, but scientists still need to identify the best targets for this future telescope. The HWO telescope should be able to image rocky exoplanets directly, so thorough research to prepare a list of high-priority targets will help avoid overlooking other Earths.
The post The search for habitable worlds appeared first on Sciworthy.
Astronomers and astrobiologists use a wide range of tools in their search for extraterrestrial life. Probes, satellites, and rovers take photographs and collect data on the geology and chemistry of planets and moons in the solar system. Radio telescopes sweep the sky, looking for signals from intelligent civilizations. And telescopes like the JWST can observe the atmospheres of distant exoplanets, potentially finding ones similar to Earth’s.
A limitation of these methods is that they assume life on other worlds is fundamentally similar to life on Earth, requiring the same balance of molecules in the atmosphere, producing the same chemicals for their metabolic processes, or developing technologies analogous to those humans make. While researchers use these assumptions as baseline markers to look for, assuming such similarities might lead them astray. Scientists looking for life using too narrow a set of parameters might miss life unlike Earthlings. Or they might mistake coincidentally similar geological, chemical, or astronomical processes for having been made by living things.
So, to complement techniques that assume alien life resembles life on Earth, scientists also consider approaches that detect signs of life while making as few assumptions as possible about what it could look like, known as agnostic biosignatures. One of these life signs with few assumptions is complexity. Though it can be difficult to quantify precisely, living things tend to create more complex systems than nonliving things. A team of researchers recently tested whether living and nonliving worlds could be distinguished solely by examining the complexity of the light-reflection patterns from their surfaces.
For this, the team treated Earth and Mars, similar planets but one with life and one without, as stand-ins for exoplanets around other stars. They collected data on the light reflected off both planets’ surfaces from a space station monitoring Earth, known as the Deep Space Climate Observatory or DSCOVR, and an orbiter around Mars observing its atmosphere, known as the Hope Probe.
The team identified 3 nearly identical wavelengths of light that these machines observe from their respective planets. From the machine databases, they collected measurements of how much light each planet reflected, called its reflectance, at these 3 wavelengths over 486 local days. By using only individual wavelengths of light rather than full photographs, the team claimed that, if their test worked, researchers could apply it to distant exoplanets that cannot be photographed in detail.
Without looking for any particular chemical or signal, the team compared these measured reflectances using a series of statistical tests to determine the variation and randomness in their reflected light, which they considered representative of the complexity of the planets’ surfaces. The researchers found that of the 27 complexity metrics they tested, Earth scored higher than Mars on 25, Mars scored higher than Earth on 1, and the planets scored the same on 1. So, even though both planets have rocky surfaces with atmospheres, weather, and cyclical changes, the one with life is measurably more intricate and dynamic, and the researchers found this difference detectable even with a small stream of light at great distances.
The researchers claimed their test demonstrated that complexity could be a valid agnostic biosignature, with caveats. One is that Earth is quite distinct from Mars, in that it has oceans and a relatively thick atmosphere. This means that processes like making and dispersing clouds and the sharp contrast between land and water could add complexity to Earth’s measurements without direct ties to living things.
They suggested 2 possible explanations for how these complicating factors relate to life on Earth. Either life allows Earth to have these factors, or Earth is inherently complex regardless of life, and therefore it can’t be used to assess how life leads to measurable complexity. To say which is the case, one would have to replicate this test with a lifeless copy of Earth. However, the team argued that Earth’s biosphere is unlikely to be wholly unrelated to its water cycle.
To bolster the validity of their methods, the team plans to expand their sample of planets to include Venus, Saturn’s moon Titan, and simulated exoplanets with modeled biochemistry and atmospheres. If the model holds up, their methodology could represent a new category of mission to find alien life, with long searches for variations in reflected light uncovering properties of distant worlds that would otherwise go unnoticed.
The post Finding alien life with light signals appeared first on Sciworthy.
A 1,000-mile-long (1,600 kilometers) Martian cloud that emerges and then quickly disappears from the Red Planet's sky nearly every day is even weirder than scientists realized. New simulations suggest that the eerie apparition can only be explained using "exotic physics" that have been theorized but never seen on Earth or anywhere else in the solar system.
The mysterious floating mass, dubbed the Arsia Mons Elongated Cloud (AMEC), frequently emerges above Arsia Mons, a 12-mile-tall (20 km) extinct volcano located in the Tharsis region, just south of the Red Planet's equator. The water vapor cloud was first spotted in 2018 by the European Space Agency's Mars Express orbiter and has since appeared nearly every morning throughout Mars' spring and summer, when increased solar radiation triggers strong surface winds. But it lasts only a few hours each day, before fully evaporating.
The AMEC can stretch up to 1,100 miles (1,800 km) long, around one-twelfth of Mars' circumference. For context, that is roughly twice the length of the U.K. or the distance between New York City and Miami.
Although the Red Planet is no stranger to giant dust clouds and occasional "iridescent streaks" of carbon dioxide, it is almost completely devoid of atmospheric water vapor. That makes it extremely rare for puffy, Earth-like clouds to form there, let alone ones so vast. As a result, scientists have struggled to explain this whacky weather.
But in a new study published Wednesday (Oct. 7) in the journal Nature Geoscience, researchers used Mars Express data to create new simulations in an effort to finally explain the AMEC. Initially, the team struggled to recreate the puzzling phenomenon. But when they abandoned traditional meteorological principles in favor of a more out-of-the-box explanation, they were eventually successful.
"To create the AMEC in our modelling, we found that we needed to include some exotic physics … physics that, while included in textbooks, is treated as theoretical and usually thought not to happen in nature," study first author Jorge Hernández-Bernal, a planetary scientist at the University of the Basque Country in Spain who was affiliated with Sorbonne University in Paris at the time of the study, said in a statement. "Once we included this physics in our simulations, the AMEC emerged just as we hoped."
The AMEC is an orographic cloud, meaning it forms as strong winds push water vapor up and over a raised structure, such as a mountain. Similar clouds also exist on Earth, including the "Levanter" cloud, which occasionally forms above the Rock of Gibraltar in southern Europe. However, the Martian equivalent cannot be explained by the same processes that occur on our planet.
On Earth, clouds form via a process called heterogeneous nucleation, in which moist air cools and condenses into ice crystals that form around tiny atmospheric particles, such as dust, salt, pollen or soot. But while Mars has plenty of atmospheric dust, that's not what's happening there.
"For the AMEC, it seems that cloud formation takes place without needing any of this 'stuff' [in the air]," said Hernández-Bernal, who has been studying the AMEC for the past six years. "Water vapour turns directly into icy cloud particles without any middle step. It's akin to droplets of condensation appearing in the middle of a room, rather than on a window."
The researchers call this "homogeneous nucleation" and say it has never been seen before in a planetary atmosphere. "It's wholly unexpected," Hernández-Bernal added.
Other scientists previously predicted that homogeneous nucleation could occur in Earth's upper atmosphere or in the skies above Venus. However, this has been deemed highly unlikely because it requires humidity levels roughly 100,000 times greater than those on our planet's surface.
Given that modern-day Mars is almost completely devoid of water, it may seem unlikely that its humidity levels could reach such lofty heights. However, the Mars Express data tells a different story.
As wind rises up the slopes of Arsia Mons, which is more than twice as tall as Mount Everest, it creates a powerful wave that shoots air into the upper atmosphere at tremendous speed. The researchers calculated that the temperature of this air can drop by up to 54 degrees Fahrenheit (30 degrees Celsius) in just 10 minutes. This not only makes it easy to freeze but also greatly increases the humidity within the wave, allowing homogeneous nucleation to take place, the simulations show.
So where does all this water come from? Some of it is already in the atmosphere, but some likely originates at the summit of Arsia Mons, which is covered with a thick layer of frost, the researchers suggested.
The new simulations mark a big step forward in our understanding of the AMEC and wider Martian meteorology.
"We don't have nearly as much information about Mars' atmosphere as we do about Earth's, so reproducing the AMEC to this degree is a big success for the model," Hernández-Bernal said.
The findings would not have been possible without the Mars Express orbiter, which used three instruments — the Visual Monitoring Camera, the High Resolution Stereo Camera and the OMEGA instrument — to map out how the AMEC takes shape and evolves every day. It is also one of the only Mars spacecraft that can see Arsia Mons in daylight.
"Mars Express discovered the AMEC, has followed up and monitored it for years, and is now helping reveal the secrets of its formation," Colin Wilson, the project scientist for Mars Express, who was not involved in the new study, said in the statement.
The discovery is also a reminder that, despite sharing the same basic principles, weather systems do not behave the same on other worlds as they do on Earth, which could have big implications for solar system exploration and the hunt for extraterrestrial life on distant exoplanets.
"While clouds on Earth and Mars seem to be governed by the same 'rules', understanding this exotic Martian cloud required exotic physics — and this may be true elsewhere in the cosmos," Wilson said.
Astronomers have spotted a never-before-seen type of "phoenix planet" rising from the ashes of a dying alien sun. The discovery, which the scientists say was "completely unexpected," raises hopes that more of these reborn alien worlds could be lurking throughout the cosmos — and may offer a glimpse of our own solar system's fate.
The unnamed exoplanet was spotted circling the white dwarf HS 0209+0832, which is located roughly 270 light-years from Earth. White dwarfs are stellar remnants, sometimes dubbed "zombie stars," that form from the leftovers of massive red giants that run out of fuel before eventually collapsing into shriveled husks. HS 0209+0832 is a particularly young white dwarf, still burning at around 63,000 degrees Fahrenheit (35,000 degrees Celsius), which suggests it made this transition within the past few million years.
Scientists previously discovered some surprising heavy elements within the visible spectrum of HS 0209+0832, which was first captured by the Hubble Space Telescope in the late 1990s. These elements — which included aluminium, titanium and nickel — are not normally found inside white dwarfs, so their presence suggested that something unusual was going on. But until now, there was not enough data to figure out what.
In the new study, published Oct. 5 in the journal Nature Astronomy, researchers took a closer look at HS 0209+0832. Using some of Hubble's updated instruments and data from other observatories, the team captured a more detailed spectrum of the stellar zombie. This revealed a high concentration of additional heavy elements, including zinc and copper, as well as niobium, which has never been seen in a white dwarf before.
The researchers think these out-of-place elements were created during the death throes of the former red giant and later coalesced into a "second-generation" planet around the newly forged white dwarf. They suspect the atmosphere of this hypothetical planet is being stripped by the white dwarf's stellar winds, causing the rare elements to fall back onto the zombie star.
Follow-up observations then revealed a recurring dip in the brightness of HS 0209+0832, suggesting that an exoplanet was repeatedly passing in front of the undead star. Based on the alien world's orbit, which lasts approximately 4.4 Earth days, and the duration of its transits in front of the star, the team predicted that the planet is roughly the size of Jupiter. (Its close proximity to the white dwarf also supports the hypothesis that its atmosphere is being stripped away.)
"Second-generation planets are worlds that form out of the material a star casts off as it dies," study first author Jamie Williams, a doctoral candidate in astronomy and astrophysics at the University of Warwick in the U.K., said in a statement. "They're incredibly rare, and finding one around a white dwarf was completely unexpected. It's a bit like finding a planet that has risen from the ashes of the very star it once orbited."
This is not the first time astronomers have spotted an exoplanet around a white dwarf. For example, in 2019, some of the authors of the new study previously spotted an alien world surrounding the white dwarf WDJ0914+1914. However, in that case, they were confident that it was a first-generation world that somehow survived its star's fiery end.
But the heavy elements that seem to be falling onto HS 0209+0832 — and the relative lack of other elements common in first-generation planets, such as silicon and iron — suggest that's not what's happened for this recently detected world.
"This pattern of elements is a telltale sign of the 's-process,' a nuclear reaction that builds heavy elements inside dying stars during their bloated red giant phase," study co-author Nicholas Stone, an astronomer at the University of Wisconsin-Madison, said in the statement. "It's a chemical signature no ordinary, 'first-generation' planet should carry, which told us that this new planet was something different."
Instead, the newly detected exoplanet likely formed directly from the material that was shed by the dying red giant after it expanded and before it collapsed in on itself.
Similar phoenix planets have been spotted alongside other stellar remnants, such as pulsars, which form when stars explode as supernovas. However, until now, such worlds have never been seen around a white dwarf.
"What's remarkable about the planet around HS 0209+0832 is that this isn't a planet from somewhere else, or a survivor from the system's birth, it looks like it was built from the very material its own star cast off as it died," study co-author Boris Gänsicke, an astrophysicist at the University of Warwick who also helped to discover the exoplanet around WDJ0914+1914 in 2019, said in the statement. "In a sense, this system has given birth to a new world using the foundations of the old one."
HS 0209+0832 may have once harbored other exoplanets when it was a red giant. But if they existed, these alien worlds likely perished in flames as the dying star ballooned — similar to what experts think will happen to Earth when the sun runs out of fuel and transitions into a red giant in around 5 billion years.
Once the sun has finished bulging, it will turn into a white dwarf too. The new discovery hints that our star could also host brand-new worlds after it has transformed, creating a sort of solar system 2.0.
"Finding this one example raises the question of how many more might be out there and might our own solar system host a second-generation planet formed from the ashes of our sun," Gänsicke said.
However, more work is required to figure out exactly how the newfound exoplanet formed and, as a result, how likely this scenario is. The researchers suspect that another object, such as a lost stellar sibling, may have been required to create the new world.
"Forming the protoplanetary disc in this situation is not easy and helps explain why these planets are so rare," Williams said. "To form a disc of material necessary to birth a planet, HS 0209+0832 likely required a companion star that pulled the ejected material back into orbit, rather than letting it escape."
You may have watched the moon block out the sun during a solar eclipse, but have you ever seen it do that to a planet? Early Tuesday (Oct. 6) morning, skywatchers across much of eastern North America will have an opportunity to watch a crescent moon pass directly in front of Jupiter. The rare alignment won't happen again for 11 years.
During the event, known as a lunar occultation, Jupiter will disappear behind the moon for up to about an hour before suddenly reappearing. The occultation will be visible before dawn from much of the eastern and central U.S., Canada and the Caribbean, while parts of Africa will experience the event during daylight, according to In-The-Sky.org.
The moon will be a beautiful waning crescent, just 20% illuminated, and Jupiter will shine brightly alongside it. The pair will rise together in the east early Tuesday morning and gradually appear to move closer as the moon travels eastward against the background stars.
When the occultation begins, Jupiter will remain hidden behind the moon for roughly an hour. No telescope will be needed to watch Jupiter disappear and reappear. However, a pair of binoculars or a small telescope will make the event much more dramatic.
Through a telescope, Jupiter will look like a tiny disc rather than a point of light and will take about a minute to disappear completely behind the moon. An easy way to photograph the event is to use a smart telescope to image the moon. (Here's everything you need to know about lunar photography).
Below are the times when Jupiter will disappear and reappear in 10 major cities Tuesday morning, according to the International Occultation Timing Association.
Outside the occultation path, Jupiter won't disappear at all. Instead, it will appear to be skimmed by the crescent moon — still a potentially spectacular sight that could produce some amazing photos. From across much of the world, the crescent moon and Jupiter will appear exceptionally close together.
The next lunar occultation of Jupiter visible from North America will occur on Nov. 27, 2037, according to When The Curves Line Up.
NASA’s Pandora satellite has started science observations of at least 20 exoplanets, measuring their host stars so Webb’s atmospheric results can be read more reliably.
The post NASA’s Pandora Mission Begins Separating Planet Light From Star Light appeared first on Curiosmos.
Editor’s Note: Astrobites is a graduate-student-run organization that digests astrophysical literature for undergraduate students. As part of the partnership between the AAS and astrobites, we occasionally repost astrobites content here at AAS Nova. We hope you enjoy this post from astrobites; the original can be viewed at astrobites.org.
Title: The Exozodi Spectral Effect: Residual Habitable Zone Dust May Bias exoEarth Characterization
Authors: Miles H. Currie et al.
First Author’s Institution: NASA Goddard Space Flight Center
Status: Published in AJ
Figure 1: Zodiacal light as seen from Cerro Paranal. [ESO/Y. Beletsky; CC BY 4.0]
This zodiacal dust is not exclusive to the solar system. Other star systems, such as Tau Ceti and Vega, have been found to host similar clouds of interplanetary dust. This means planets imaged in these systems will also have emission from this dust mixed into the light that we observe from the planets. The Habitable Worlds Observatory (HWO) is a future space telescope mission under development by NASA. One of its primary science goals is to directly image 25 Earth-like planets in the habitable zones of nearby stars and look for signs of life (or biosignatures) in these planets’ atmospheres. Exozodiacal dust (aka exozodi) represents the biggest source of astrophysical noise that will need to be subtracted out from HWO observations of exoEarths. The authors of today’s article look at the potential impact of exozodi emission on the spectra of exoEarth atmospheres.
Figure 2: Different models of three “zodis” of dust observed at an inclination of 60 degrees plotted across HWO’s potential wavelength range. The gray scattering model is shown in green, the solar system’s model is shown in black, with the red and blue debris disk models shown in their respective colors. The top panel shows the flux contrast between the dust and the star. The middle panel shows the flux per area. The bottom panel shows the total flux captured with a 7.2-meter HWO with the thin blue line representing the spectrum of an Earth twin 10 parsecs (33 light-years) away for comparison. [Currie et al. 2026]
The authors first assume four different models of exozodi dust and how the dust’s emission changes with wavelength. The first model assumes a dust cloud that acts as a gray scatterer, meaning the particles scatter all wavelengths of light with no preference, and the second model’s dust acts just like the solar system’s does. However, it’s unknown whether the composition of exozodi will be the same as the solar system’s. Therefore, they adopt two more models of exozodi that act just like debris disks that have different compositions. One model is bluer in color because it is made up of smaller particles that preferentially scatter blue light, and the other model is redder in color because it is made up of bigger dust particles or different chemical compositions. Each of these models over HWO’s wavelength range can be seen in Figure 2. The authors then simulate a modern Earth atmosphere (both clear and 50% cloudy) as well as an Archean Earth atmosphere to understand how different exozodi models will affect observations of different exoplanet atmosphere conditions and compositions.
In general, the effect that zodiacal dust has on the spectra of Earth-like planets can be broken down into two categories: its effect on the continuum and on the spectral features. The continuum is the object’s light emitted over all wavelengths and uninterrupted by spectral features. Spectral features are absorption and emission lines. These create either a dip or peak in the spectrum where atoms have either absorbed or emitted light at that particular wavelength. Lines at specific wavelengths tell us that a certain material is there, providing a list of possible chemicals that could be present in the planet’s atmosphere. For a brief summary of spectroscopy more generally, see here.
In the case of the continuum, exozodiacal emission raises the continuum, meaning the base flux of the planet is raised and absorption lines become more shallow. These effects can be seen in Figure 3, where the authors’ simulated spectra are plotted with and without zodiacal dust included. Not only is the continuum elevated for all models including zodiacal dust, notice how the dips become shallower at longer wavelengths. Because dust primarily radiates thermally, the red debris disk model nearly smooths out all dips beyond 1.25 microns! Molecules that absorb at these longer wavelengths, such as water or methane, may not be correctly identified with this type of exozodiacal emission.
Figure 3: Spectra of simulated modern-Earth atmospheres for clear (solid bright lines) and cloudy (solid dimmer lines) scenarios. The Archean Earth atmosphere is plotted in dotted gray. The redder exozodiacal spectrum has an elevated continuum and smoothed spectral features as opposed to the original, zodi-free spectrum plotted in black. [Currie et al. 2026, with annotations by Kaz Gary]
From Figure 3, the effects of zodiacal dust are minimized with a bluer zodiacal dust model. This means systems with “bluer” zodiacal dust may be more optimal for HWO observations, as bluer dust does not scatter as much starlight as gray, solar system–like, or red dust. From their results, the authors recommend that the residual exozodi-to-planet flux ratio (in the V-band wavelengths) be kept to less than 10-2 in order to correctly understand the line depths (identify if a molecule is present or not) and 10-3 in order to accurately retrieve molecular abundances (understand how much of a molecule is present in the atmosphere). Dust is pesky enough here on Earth, but to find life on another planet like ours, we’ll dust have to deal with it.
Original astrobite edited by Anavi Uppal.
About the author, Kaz Gary:
I am a fourth-year PhD candidate at The Ohio State University with a passion for planets. My current work focuses on modeling exoplanet observations for the Habitable Worlds Observatory and understanding planetary atmospheres. Outside of research, I help develop planetarium shows and love all forms of science communication. In my free time, I enjoy playing tabletop RPGs, painting, watching terrible reality TV, and hanging out with my pet hedgehog.
The post Dust Deal with It appeared first on AAS Nova.
The Moon may have emerged largely intact within hours of the colossal impact that shaped its birth. Earth has an unusually large moon for a planet of its size and position in the solar system, yet scientists still do not fully understand how that companion came to exist. Now, researchers from the Southwest Research Institute [...]
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