New study revises our picture of the most common planets in the galaxy

A new study finds that many “mini-Neptunes”—perhaps the most common planets in the galaxy—are under so much pressure from their heavy atmospheres that the surface is likely compressed solid. Illustration Credit: NASA/JPL-Caltech/R. Hurt (IPAC)

As telescopes have become more powerful, it’s turned out our solar system is not the only game in town: There are millions of other planets out there in the galaxy. 

But we’re still teasing out clues about what they are actually like. 

One of the puzzles is a kind of planet that appears to be one of the most common types in the universe. Known as “mini-Neptunes” because they run a little smaller than Neptune in our solar system, these planets are made of some mix of rock and metal, with thick atmospheres mostly made of hydrogen, helium, and perhaps water. Strangely, despite their abundance elsewhere, they have no analogue in our own solar system, making the population something of an enigma. 

But a new study published Nov. 5, led by Prof. Eliza Kempton with the University of Chicago, adds a new wrinkle to our best picture yet of these distant worlds.

Geologists discover the first evidence of 4.5-billion-year-old “proto-Earth”

“This is maybe the first direct evidence that we’ve preserved the proto Earth materials,” says Nicole Nie. An artist’s illustration shows a rocky proto Earth bubbling with lava.
Image Credit: MIT News; iStock
(CC BY-NC-ND 4.0)

Scientists at MIT and elsewhere have discovered extremely rare remnants of “proto-Earth,” which formed about 4.5 billion years ago, before a colossal collision irreversibly altered the primitive planet’s composition and produced the Earth as we know today. Their findings, reported today in the journal Nature Geosciences, will help scientists piece together the primordial starting ingredients that forged the early Earth and the rest of the solar system.

Billions of years ago, the early solar system was a swirling disk of gas and dust that eventually clumped and accumulated to form the earliest meteorites, which in turn merged to form the proto-Earth and its neighboring planets.

In this earliest phase, Earth was likely rocky and bubbling with lava. Then, less than 100 million years later, a Mars-sized meteorite slammed into the infant planet in a singular “giant impact” event that completely scrambled and melted the planet’s interior, effectively resetting its chemistry. Whatever original material the proto-Earth was made from was thought to have been altogether transformed.

Raging winds on Mars

Images of dust devils, whirlwinds of dust that are blown across Mars’ surface.
Image Credit: ESA/TGO/CaSSIS for CaSSIS
(CC BY SA 3.0 IGO)

On Mars, dust devils and winds reach speeds of up to 160 km/h and are therefore faster than previously assumed: This shows a study by an international research team led by the University of Bern. The researchers analyzed images taken by the Bernese Mars camera CaSSIS and the stereo camera HRSC with the help of machine learning. The study provides a valuable data basis for a better understanding of atmospheric dynamics, which is important for better climate models and future Mars missions.

Despite the very thin Martian atmosphere, there are also winds on Mars that are central to the climate and the distribution of dust. The wind movements and the whirling up of dust also create so-called dust devils, rotating columns of dust and air that move across the surface. In images of Mars, the wind itself is invisible, but dust devils are clearly visible. Due to their movement, they are valuable indicators for researchers to determine the otherwise invisible winds.

Moon-forming disc around massive planet

An artistic rendering of a dust and gas disc encircling the young exoplanet, CT Cha b, 625 light-years from Earth. Spectroscopic data from the NASA/ESA/CSA James Webb Space Telescope suggest the disc contains the raw materials for moon formation. The planet appears at lower right, while its host star and surrounding protoplanetary disc are visible in the background. 
Image Credit: NASA, ESA, CSA, STScI, G. Cugno (University of Zürich, NCCR PlanetS), S. Grant (Carnegie Institution for Science), J, Olmsted (STScI), L. Hustak (STScI)

The NASA/ESA/CSA James Webb Space Telescope has provided the first direct measurements of the chemical and physical properties of a potential moon-forming disc encircling a large exoplanet. The carbon-rich disc surrounding the world called CT Cha B, which is located 625 light years away from Earth, is a possible construction yard for moons, although no moons are detected in the Webb data.

Our Solar System contains eight major planets, and more than 400 known moons orbiting six of these planets. Where did they all come from? There are multiple formation mechanisms. The case for large moons, like the four Galilean satellites around Jupiter, is that they condensed out of a dust and gas disc encircling the planet when it formed. But that would have happened over 4 billion years ago, and there is scant forensic evidence today.

Cosmic glass found only in Australia reveals ancient asteroid impact

The newly discovered tektites or ‘cosmic glass’.
Photo Credit: Et al. ‘Earth and Planetary Science Letters’

Curtin researchers have helped uncover evidence of a mysterious giant asteroid impact, hidden not in a crater but in tiny pieces of glass found only in Australia.

The discovery centers on rare tektites, which are natural glasses created when a space rock slams into Earth, melting surface material and hurling it hundreds or even thousands of kilometers. The newly discovered type of tektites has so far been found exclusively in an area mainly within South Australia.

Co-author Professor Fred Jourdan, from Curtin’s School of Earth and Planetary Sciences, said finding a new tektite field is like opening a fresh chapter in Earth’s violent geological past.

“These glasses are unique to Australia and have recorded an ancient impact event we did not even know about,” Professor Jourdan said.

New Mars research reveals multiple episodes of habitability in Jezero Crater

Jerezo Carter: Mars 2020 Rover Landing Site
Image Credit: NASA/JPL-Caltech/MSSS/JHUAPL

New research using NASA’s Perseverance rover has uncovered strong evidence that Mars’ Jezero Crater experienced multiple episodes of fluid activity — each with conditions that could have supported life.

By analyzing high-resolution geochemical data from the rover, scientists have identified two dozen types of minerals, the building blocks of rocks, that help reveal a dynamic history of volcanic rocks that were altered during interactions with liquid water on Mars. The findings, published in the Journal of Geophysical Research: Planets, provide important clues for the search for ancient life and help guide Perseverance’s ongoing sampling campaign.

The study was led by Rice University graduate student Eleanor Moreland and employed the Mineral Identification by Stoichiometry (MIST) algorithm — a tool developed at Rice — to interpret data from Perseverance’s Planetary Instrument for X-ray Lithochemistry (PIXL). PIXL bombards Martian rocks with X-rays to reveal their chemical composition, offering the most detailed geochemical measurements ever collected on another planet, according to the study.

AI unveils: Meteoroid impacts cause Mars to shake

High-resolution CaSSIS image of one of the newly discovered impact craters in Cerberus Fossae. The so-called "blast zone", i.e. the dark rays around the crater, is clearly visible.
Image Credit: © ESA/TGO/CaSSIS
(CC-BY-SA 3.0 IGO)

Meteoroid impacts create seismic waves that cause Mars to shake stronger and deeper than previously thought: This is shown by an investigation using artificial intelligence carried out by an international research team led by the University of Bern. Similarities were found between numerous meteoroid impacts on the surface of Mars and marsquakes recorded by NASA's Mars lander InSight. These findings open up a new perspective on the impact rate and seismic dynamics of the Red Planet.

Meteoroid impacts have a significant influence on the landscape evolution of solid planetary bodies in our solar system, including Mars. By studying craters – the visible remnants of these impacts – important properties of the planet and its surface can be determined. Satellite images help to constrain the formation time of impact craters and thus provide valuable information on impact rates.

A recently published study led by Dr. Valentin Bickel from the Center for Space and Habitability at the University of Bern presents the first comprehensive catalog of impacts on the Martian surface that took place near NASA's Mars lander during the InSight mission between December 2018 and December 2022. Bickel is also an InSight science team member. The study has just been published in the journal Geophysical Research Letters.

A Super-Earth laboratory for searching life elsewhere in the Universe

In green, the habitable zone in the orbit of planet HD 20794.
Image Credit: (Dumusque et al. 2025) © Gabriel Pérez Díaz, SMM (IAC)

Thirty years after the discovery of the first exoplanet, more than 7000 have been discovered in our Galaxy. But there are still billions more to be discovered! At the same time, exoplanetologists have begun to take an interest in their characteristics, with the aim of finding life elsewhere in the Universe. This is the background to the discovery of super-Earth HD 20794 d by an international team including the University of Geneva (UNIGE) and the NCCR PlanetS. The new planet lies in an eccentric orbit, so that it oscillates in and out of its star’s habitable zone. This discovery is the result of 20 years of observations using the best telescopes in the world. The study is published today in the journal Astronomy & Astrophysics.

‘‘Are we alone in the Universe?’’ For thousands of years, this question was confined to philosophy, and it is only very recently that modern science has begun to provide solid hypotheses and evidence to answer it. However, astronomers are making slow progress. Each new discovery, whether theoretical or observational, adds to the edifice by pushing back the limits of knowledge. This was the case with the discovery in 1995 of the first planet orbiting a star other than the Sun, which earned two UNIGE researchers, Michel Mayor and Didier Queloz, the 2019 Physics Nobel Prize.

Nearly thirty years later, astronomers have taken many small steps towards detecting more than 7,000 exoplanets. The current scientific consensus points to the existence of a planetary system for every star in our galaxy. Astronomers are now looking for exoplanets that are easier to characterize or have interesting features to test their hypotheses and consolidate their knowledge. This is the case of planet HD 20794 d, which has just been detected by a team that includes members of the UNIGE Astronomy Department. 

SwRI-designed experiments corroborate theory about how Titan maintains its atmosphere

To understand the persistent thick atmosphere on Saturn's largest moon, SwRI worked with the Carnegie Institution for Science Laboratory to create conditions mimicking those at Titan's rocky core. These laboratory experiments heated and pressurized tubes of organics, producing nitrogen and methane, gases necessary to maintain Titan's atmosphere.
Photo Credit: Courtesy of SwRI

Southwest Research Institute partnered with the Carnegie Institution for Science to perform laboratory experiments to better understand how Saturn’s moon Titan can maintain its unique nitrogen-rich atmosphere. 

Titan is the second largest moon in our solar system and the only one that has a significant atmosphere. 

“While just 40% the diameter of the Earth, Titan has an atmosphere 1.5 times as dense as the Earth’s, even with a lower gravity,” said SwRI’s Dr. Kelly Miller, lead author of a paper about these findings published in the journal Geochimica et Cosmochimica Acta. “Walking on the surface of Titan would feel a bit like scuba diving.”

The origin, age, and evolution of this atmosphere, which is roughly 95% nitrogen and 5% methane, has puzzled scientists since it was discovered in 1944.

“The presence of methane is critical to the existence of Titan’s atmosphere,” Miller says. “The methane is removed by reactions caused by sunlight and would disappear in about 30 million years after which the atmosphere would freeze onto the surface. Scientists think an internal source must replenish the methane, or else the atmosphere has a geologically short lifetime.”

New data on atmosphere from Earth to the edge of space

Clouds in Antarctica.
Our weather is influenced by many factors, at ground level (such as mountains and human activity), interactions in our atmosphere, and space (such as auroras and magnetic fields).
Photo Credit: © Kaoru Sato

A team led by researchers at the University of Tokyo have created a dataset of the whole atmosphere, enabling new research to be conducted on previously difficult-to-study regions. Using a new data-assimilation system called JAGUAR-DAS, which combines numerical modeling with observational data, the team created a nearly 20-yearlong set of data spanning multiple levels of the atmosphere from ground level up to the lower edges of space. Being able to study the interactions of these layers vertically and around the globe could improve climate modeling and seasonal weather forecasting. There is also potential for interdisciplinary research between atmospheric scientists and space scientists, to investigate the interplay between space and our atmosphere and how it affects us on Earth.

Complaining about the weather, and about weather forecasters when they get things wrong, is a popular pastime for many. But a meteorologist’s job is not easy. Our atmosphere is multilayered, interconnected and complex, and global climate change is making it even harder to forecast both long-term and sudden, extreme weather events.

SwRI models pluto-charon formation scenario that mimics earth-moon system

Using advanced models, SwRI led new research that indicates that the formation of Pluto and Charon may parallel that of the Earth-Moon system. In the resulting 'kiss-and-captureâ regime, Pluto and Charon collide and stick together in the shape of a snowman. They rotate as one body until Pluto pushes Charon out into a stable orbit.
Image Credit: Courtesy of SwRI/Adeene Denton/Robert Melikyan

A NASA postdoctoral researcher at Southwest Research Institute has used advanced models that indicate that the formation of Pluto and Charon may parallel that of the Earth-Moon system. Both systems include a moon that is a large fraction of the size of the main body, unlike other moons in the solar system. The scenario also could support Pluto’s active geology and possible subsurface ocean, despite its location at the frozen edge of the solar system.

“We think the Earth-Moon system initiated when a Mars-sized object hit the Earth and led to the formation of our large Moon sometime later,” said Dr. Adeene Denton, who led the research, published in Nature Geoscience. “In comparison, Mars has two tiny moons that look like potatoes, while the moons of the giant planets make up a small fraction of their total systems.”

Signs of life detectable in single ice grain emitted from extraterrestrial moons

An artist’s rendition of Saturn’s moon Enceladus depicts hydrothermal activity on the seafloor and cracks in the moon’s icy crust that allow material from the watery interior to be ejected into space. New research shows that instruments destined for the next missions could find traces of a single cell in a single ice grain contained in a plume.
Illustration Credit: NASA/JPL-Caltech

The ice-encrusted oceans of some of the moons orbiting Saturn and Jupiter are leading candidates in the search for extraterrestrial life. A new lab-based study led by the University of Washington in Seattle and the Freie Universität Berlin shows that individual ice grains ejected from these planetary bodies may contain enough material for instruments headed there in the fall to detect signs of life, if such life exists.

“For the first time we have shown that even a tiny fraction of cellular material could be identified by a mass spectrometer onboard a spacecraft,” said lead author Fabian Klenner, a UW postdoctoral researcher in Earth and space sciences. “Our results give us more confidence that using upcoming instruments, we will be able to detect lifeforms similar to those on Earth, which we increasingly believe could be present on ocean-bearing moons.”

The open-access study was published March 22 in Science Advances. Other authors in the international team are from The Open University in the U.K.; NASA’s Jet Propulsion Laboratory; the University of Colorado, Boulder; and the University of Leipzig.

The Cassini mission that ended in 2017 discovered parallel cracks near the south pole of Saturn’s moon Enceladus. Emanating from these cracks are plumes containing gas and ice grains. NASA’s Europa Clipper mission, scheduled to launch in October, will carry more instruments to explore in even more detail an icy moon of Jupiter, Europa.

Icy impacts: Planetary scientists use physics and images of impact craters to gauge the thickness of ice on Europa

Brandon Johnson and his team study impact craters around the solar system for clues about planetary bodies’ history and composition.
Photo Credit: Rebecca Robinos / Purdue University

Sometimes planetary physics is like being in a snowball fight. Most people, if handed an already-formed snowball, can use their experience and the feel of the ball to guess what kind of snow it is comprised of: packable and fluffy, or wet and icy.

Using nearly the same principles, planetary scientists have been able to study the structure of Europa, Jupiter’s icy moon.

Europa is a rocky moon, home to saltwater oceans twice the volume of Earth’s, encased in a shell of ice. Scientists have long thought that Europa may be one of the best places in our solar system to look for nonterrestrial life. The likelihood and nature of that life, though, heavily depend on the thickness of its icy shell, something astronomers have not yet been able to measure.

A team of planetary science experts including Brandon Johnson, an associate professor, and Shigeru Wakita, a research scientist, in the Department of Earth, Atmospheric, and Planetary Sciences in Purdue University’s College of Science, announced in a new paper published in Science Advances that Europa’s ice shell is at least 20 kilometers thick.

Juno Spacecraft Measures Oxygen Production on Jupiter's Moon, Europa

For the first time, SwRI scientists used the Jovian Auroral Distributions Experiment (JADE) instrument to definitively detect oxygen and hydrogen in the atmosphere of one of Jupiter's largest moons, Europa. NASA's Juno spacecraft, using its SwRI-developed instrument, made the measurements during a 2022 flyby of Europa.
Image Credit: Courtesy of NASA/JPL/University of Arizona

NASA’s Juno spacecraft has directly measured charged oxygen and hydrogen molecules from the atmosphere of one of Jupiter’s largest moons, Europa. According to a new study co-authored by SwRI scientists and led by Princeton University, these observations provide key constraints on the potential oxygenation of its subsurface ocean.

“These findings have direct implications on the potential habitability of Europa,” said Juno Principal Investigator Dr. Scott Bolton of SwRI, a co-author of the study. “This study provides the first direct in-situ measurement of water components existing in Europa’s atmosphere, giving us a narrow range that could support habitability.”

In 2022, Juno completed a flyby of Europa, coming as close as 352 kilometers to the moon. The SwRI-developed Jovian Auroral Distributions Experiment (JADE) instrument aboard Juno detected significant amounts of charged molecular oxygen and hydrogen lost from the atmosphere.

Groundbreaking survey reveals secrets of planet birth around dozens of stars

This research brings together observations of more than 80 young stars that might have planets forming around them in spectacular discs. This small selection from the survey shows 10 discs from the three regions of our galaxy observed in the papers. V351 Ori and V1012 Ori are located in the most distant of the three regions, the gas-rich cloud of Orion, some 1600 light-years from Earth. DG Tau, T Tau, HP Tau, MWC758 and GM Aur are located in the Taurus region, while HD 97048, WW Cha and SZ Cha can be found in Chamaeleon I, all of which are about 600 light-years from Earth.  The images shown here were captured using the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument mounted on ESO’s Very Large Telescope (VLT). SPHERE’s state-of-the-art extreme adaptive optics system corrects for the turbulent effects of Earth’s atmosphere, yielding crisp images of the discs around stars. The stars themselves have been covered with a coronagraph — a circular mask that blocks their intense glare, revealing the faint discs around them.  The discs have been scaled to appear roughly the same size in this composition. 
Full Size Zoomable Image
Image Credit: ESO/C. Ginski, A. Garufi, P.-G. Valegård et al.

In a series of studies, a team of astronomers has shed new light on the fascinating and complex process of planet formation. The stunning images, captured using the European Southern Observatory's Very Large Telescope (ESO’s VLT) in Chile, represent one of the largest ever surveys of planet-forming discs. The research brings together observations of more than 80 young stars that might have planets forming around them, providing astronomers with a wealth of data and unique insights into how planets arise in different regions of our galaxy.

“This is really a shift in our field of study,” says Christian Ginski, a lecturer at the University of Galway, Ireland, and lead author of one of three new papers published today in Astronomy & Astrophysics. “We’ve gone from the intense study of individual star systems to this huge overview of entire star-forming regions.”

Water May Have Flowed Intermittently in Martian Valleys for Hundreds of Millions of Years

Detail of an unnamed valley network on Mars. Impact craters are marked with blue and red circles. Craters marked in red postdate the valley network while those marked in blue predate the valley network. Dashed circles have a lower degree of superposition certainty with the valley network. Dashed black line is the mapped valley network. (a) overview of the valley system. The entire basin is outlined in white; the highland areas that have undergone less erosion are outlined in black. (b) detail of the area marked in (a).
Image Credit: MOLA MEGDR, NASA/USGS; THEMIS mosaic, ASU/NASA/USGS; CTX, NASA/MSSS.

Using impact craters as a dating tool, Planetary Science Institute Research Scientist Alexander Morgan has determined maximum timescales for the formation of Martian valley networks shaped by running water.

“Mars today is a global desert, but its surface preserves extensive evidence of past flowing water, including what appear to be river valleys. The timescale over which these valleys formed has big implications for early Mars’ habitability, as long eras with stable liquid water would be more conducive to life,” said Morgan, sole author of “New maximum constraints on the era of Martian valley network formation” that appears in Earth and Planetary Science Letters.

Martian valley networks formed more than 3 billion years ago and have long been considered among the strongest pieces of evidence of liquid water on early Mars. Previous work has found that it took a minimum of tens of thousands of years to erode these valleys, but the frequency of flow events, and thus the total time era over which the valleys formed, has not been constrained.