In a new study published in the journal Nature Astronomy, Konstantin Batygin (PhD '12), professor of planetary science at Caltech; and Fred C. Adams, professor of physics and astronomy at the University of Michigan; provide a detailed look into Jupiter's primordial state.

Their calculations reveal that roughly 3.8 million years after the solar system's first solids formed-a key moment when the disk of material around the Sun, known as the protoplanetary nebula, was dissipating-Jupiter was significantly larger and had an even more powerful magnetic field.

"Our ultimate goal is to understand where we come from, and pinning down the early phases of planet formation is essential to solving the puzzle," Batygin says. "This brings us closer to understanding how not only Jupiter but the entire solar system took shape."

Batygin and Adams approached this question by studying Jupiter's tiny moons Amalthea and Thebe, which orbit even closer to Jupiter than Io, the smallest and nearest of the planet's four large Galilean moons. Because Amalthea and Thebe have slightly tilted orbits, Batygin and Adams analyzed these small orbital discrepancies to calculate Jupiter's original size: approximately twice its current radius, with a predicted volume that is the equivalent of over 2,000 Earths. The researchers also determined that Jupiter's magnetic field at that time was approximately 50 times stronger than it is today.

Adams highlights the remarkable imprint the past has left on today's solar system: "It's astonishing that even after 4.5 billion years, enough clues remain to let us reconstruct Jupiter's physical state at the dawn of its existence."

Importantly, these insights were achieved through independent constraints that bypass traditional uncertainties in planetary formation models-which often rely on assumptions about gas opacity, accretion rate, or the mass of the heavy element core.

Instead, the team focused on the orbital dynamics of Jupiter's moons and the conservation of the planet's angular momentum-quantities that are directly measurable. Their analysis establishes a clear snapshot of Jupiter at the moment the surrounding solar nebula evaporated, a pivotal transition point when the building materials for planet formation disappeared and the primordial architecture of the solar system was locked in.

The results add crucial details to existing planet formation theories, which suggest that Jupiter and other giant planets around other stars formed via core accretion, a process by which a rocky and icy core rapidly gathers gas.

These foundational models were developed over decades by many researchers, including Caltech's Dave Stevenson, the Marvin L. Goldberger Professor of Planetary Science, Emeritus. This new study builds upon that foundation by providing more exact measurements of Jupiter's size, spin rate, and magnetic conditions at an early, pivotal time.

Batygin emphasizes that while Jupiter's first moments remain obscured by uncertainty, the current research significantly clarifies our picture of the planet's critical developmental stages. "What we've established here is a valuable benchmark," he says. "A point from which we can more confidently reconstruct the evolution of our solar system."

The paper is titled "Determination of Jupiter's Primordial Physical State." Funding was provided by Caltech, the David and Lucile Packard Foundation, the National Science Foundation, the University of Michigan, and the Leinweber Center for Theoretical Physics at the University of Michigan.

Research Report:Determination of Jupiter's primordial physical state

]]> Fri, 23 MAY 2025 02:09:15 AEST Los Angeles CA (SPX) May 19, 2025 - The Ultraviolet Spectrograph (UVS) aboard NASA's Europa Clipper, developed by the Southwest Research Institute (SwRI), has completed its initial commissioning phase following the spacecraft's October 14, 2024, launch. The mission aims to reach the Jovian system by 2030, where it will conduct numerous close flybys of the icy moon Europa, believed to harbor a subsurface ocean that could potentially support life.

Europa-UVS is one of nine scientific instruments aboard the Europa Clipper, including another SwRI-led instrument, the MAss Spectrometer for Planetary EXploration (MASPEX). The UVS gathers ultraviolet light to analyze the composition of Europa's atmospheric gases and surface materials.

"SwRI scientists started this process in January from NASA's Jet Propulsion Laboratory, however, we had to evacuate due to the fires in southern California," said SwRI Institute Scientist Dr. Kurt Retherford, principal investigator (PI) of Europa-UVS. "We had to wait until May to open the instrument's aperture door and collect UV light from space for the first time. We observed a part of the sky, verifying that the instrument is performing well."

SwRI has a history of providing ultraviolet spectrographs for numerous spacecraft, including ESA's Rosetta comet orbiter, NASA's New Horizons mission to Pluto, the Lunar Reconnaissance Orbiter, and the Juno mission to Jupiter.

"Europa-UVS is the sixth in this series, and it benefits greatly from the design experience gained by our team from the Juno-UVS instrument, launched in 2011, as it pertains to operating in Jupiter's harsh radiation environment," said Matthew Freeman, project manager for Europa-UVS and director of SwRI's Space Instrumentation Department. "Each successive instrument we build is more capable than its predecessor."

Weighing just over 40 pounds (19 kg) and drawing only 7.9 watts of power, UVS is smaller than a microwave oven but capable of measuring the relative concentrations of various elements and molecules in Europa's atmosphere. A similar UVS instrument aboard ESA's Jupiter Icy Moons Explorer, launched in 2023, is currently studying Jupiter's icy moons and gases from the volcanic moon Io. Having two UVS instruments in the Jupiter system simultaneously offers significant scientific benefits.

In addition to atmospheric studies, Europa-UVS will also search for potential plumes erupting from Europa's subsurface.

"Europa-UVS will hunt down potential plumes spouting from Europa's icy surface and study them to understand what they tell us about the nature of subsurface water reservoirs," said Dr. Thomas Greathouse, SwRI staff scientist and Europa-UVS co-deputy PI. "The instrument is working fabulously, and we're excited about its ability to make new discoveries once we get to Jupiter."

NASA's Jet Propulsion Laboratory (JPL) manages the Europa Clipper mission for NASA's Science Mission Directorate in Washington, D.C. The mission is a collaborative effort with the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland.

]]> Fri, 23 MAY 2025 02:09:15 AEST Paris, France (SPX) May 13, 2025 - The James Webb Space Telescope, a collaboration between NASA, ESA, and CSA, has provided fresh insights into the intense auroras that dance around Jupiter, the largest planet in our Solar System. These auroras, hundreds of times brighter than those on Earth, have been studied with Webb's highly sensitive instruments, revealing previously unseen details.

Jupiter's auroras form when high-energy particles enter the planet's atmosphere near its magnetic poles and collide with gas atoms. Unlike Earth's auroras, which are driven mainly by solar storms, Jupiter's immense magnetic field draws in charged particles not only from the solar wind but also from its volcanic moon Io. Io's volcanic eruptions eject particles that can escape the moon's gravity and enter Jupiter's magnetosphere, adding to the auroral spectacle. As these particles are accelerated to extreme speeds, they collide with Jupiter's atmosphere, generating the powerful light displays observed.

Webb's Near-InfraRed Camera (NIRCam) captured this dynamic activity on Christmas Day 2023. Jonathan Nichols, leading the study from the University of Leicester, described the experience as a thrilling surprise. "What a Christmas present it was - it just blew me away!" he said. "We wanted to see how quickly the auroras change, expecting it to fade in and out ponderously, perhaps over a quarter of an hour or so. Instead, we observed the whole auroral region fizzing and popping with light, sometimes varying by the second."

Their findings reveal that the trihydrogen ion (H3+) emissions are far more variable than previously thought, providing new clues about the heating and cooling processes in Jupiter's upper atmosphere.

In an unexpected twist, simultaneous ultraviolet observations by the Hubble Space Telescope revealed a puzzling discrepancy. "Bizarrely, the brightest light observed by Webb had no real counterpart in Hubble's pictures," Nichols explained. "This has left us scratching our heads. In order to cause the combination of brightness seen by both Webb and Hubble, we need to have an apparently impossible combination of high quantities of very low energy particles hitting the atmosphere - like a tempest of drizzle! We still don't understand how this happens."

Future studies will compare these Webb observations with data from NASA's Juno spacecraft, aiming to unravel the mysterious bright emission. These insights may also inform the upcoming Jupiter Icy Moons Explorer (Juice) mission by the European Space Agency, which is set to study Jupiter and its ocean-bearing moons Ganymede, Callisto, and Europa. Juice will use its seven scientific instruments, including two imagers, to further investigate Jupiter's complex magnetic environment.

These findings were published in Nature Communications and were part of Webb's Cycle 2 observing programme #4566 and Hubble's observing programme #17471.

Webb is the largest, most powerful telescope ever launched into space. ESA contributed to the mission by providing the launch service, including the adaptation of the Ariane 5 launch vehicle, as well as the NIRSpec spectrograph and 50% of the MIRI instrument, developed in collaboration with JPL and the University of Arizona.

Research Report:Nature Communications

]]> Fri, 23 MAY 2025 02:09:15 AEST Los Angeles CA (SPX) May 02, 2025 - NASA's Juno mission has delivered unprecedented insights into the subsurface dynamics of both Jupiter and its volcanic moon, Io. The spacecraft's latest observations have unveiled the temperature structure beneath Jupiter's cloud cover and mapped residual volcanic heat beneath Io's surface.

Using its Microwave Radiometer (MWR) and Jovian Infrared Auroral Mapper (JIRAM), Juno captured data that supports a new model for the fast-moving jet stream encircling Jupiter's north pole. The results were presented at the European Geosciences Union General Assembly in Vienna.

"Everything about Jupiter is extreme," said Scott Bolton, Juno's principal investigator at the Southwest Research Institute. "We're getting a closer look at the immensity of energy this gas giant wields."

Juno's instruments, originally designed to peer into Jupiter, have also been turned on Io. By combining MWR readings with JIRAM infrared data, scientists detected cooling lava flows beneath Io's crust across the moon's entire surface. According to Shannon Brown of NASA's Jet Propulsion Laboratory, "We were surprised by what we saw: evidence of still-warm magma that hasn't yet solidified below Io's cooled crust."

The findings suggest that about 10% of Io's surface harbors slowly cooling lava beneath the crust. These flows act as efficient heat radiators, transporting internal heat outward, much like a car radiator. This process helps explain how Io so rapidly renews its surface.

JIRAM data also revealed that Io's most energetic volcanic eruption, initially recorded during Juno's Dec. 27, 2024 flyby, remained active into March 2025 and may still be ongoing. Another close approach is scheduled for May 6, with Juno flying within 55,300 miles (89,000 kilometers) of the moon.

Juno's 53rd orbit on Feb. 18, 2023, marked the start of radio occultation experiments aimed at measuring Jupiter's atmospheric temperature structure. By analyzing how radio waves bend while passing through the atmosphere, researchers obtained the first temperature measurements of Jupiter's north polar stratospheric cap, finding it about 11 degrees Celsius cooler than its surroundings and encircled by 100 mph (161 kph) winds.

Extended JunoCam and JIRAM data also allowed scientists to track the motion of Jupiter's polar cyclones. Observations confirmed the cyclones' gradual poleward drift due to beta drift and revealed complex interactions resembling spring-like oscillations.

"These competing forces result in the cyclones 'bouncing' off one another... stabilizing the entire configuration," said Yohai Kaspi, a Juno co-investigator from the Weizmann Institute of Science.

The new cyclone model has implications for understanding atmospheric systems on other planets, including Earth. Juno's evolving orbit continues to provide new perspectives on Jupiter's radiation belts and weather phenomena.

"It's a little scary, but we've built Juno like a tank," said Bolton. "We're learning more about this intense environment each time we go through it."

Research Report:NASA's Juno Mission Gets Under Jupiter's and Io's Surface

]]> Fri, 23 MAY 2025 02:09:15 AEST Hampton VA (SPX) Apr 23, 2025 - When a planet's orbit brings it between Earth and a distant star, it's more than just a cosmic game of hide and seek. It's an opportunity for NASA to improve its understanding of that planet's atmosphere and rings. Planetary scientists call it a stellar occultation and that's exactly what happened with Uranus on April 7.

Observing the alignment allows NASA scientists to measure the temperatures and composition of Uranus' stratosphere - the middle layer of a planet's atmosphere - and determine how it has changed over the last 30 years since Uranus' last significant occultation.

"Uranus passed in front of a star that is about 400 light years from Earth," said William Saunders, planetary scientist at NASA's Langley Research Center in Hampton, Virginia, and science principal investigator and analysis lead, for what NASA's team calls the Uranus Stellar Occultation Campaign 2025. "As Uranus began to occult the star, the planet's atmosphere refracted the starlight, causing the star to appear to gradually dim before being blocked completely. The reverse happened at the end of the occultation, making what we call a light curve. By observing the occultation from many large telescopes, we are able to measure the light curve and determine Uranus' atmospheric properties at many altitude layers."

This data mainly consists of temperature, density, and pressure of the stratosphere. Analyzing the data will help researchers understand how the middle atmosphere of Uranus works and could help enable future Uranus exploration efforts.

To observe the rare event, which lasted about an hour and was only visible from Western North America, planetary scientists at NASA Langley led an international team of over 30 astronomers using 18 professional observatories.

"This was the first time we have collaborated on this scale for an occultation," said Saunders. "I am extremely grateful to each member of the team and each observatory for taking part in this extraordinary event. NASA will use the observations of Uranus to determine how energy moves around the atmosphere and what causes the upper layers to be inexplicably hot. Others will use the data to measure Uranus' rings, its atmospheric turbulence, and its precise orbit around the Sun."

Knowing the location and orbit of Uranus is not as simple as it sounds. In 1986, NASA's Voyager 2 spacecraft became the first and only spacecraft to fly past the planet - 10 years before the last bright stellar occultation occured in 1996. And, Uranus' exact position in space is only accurate to within about 100 miles, which makes analyzing this new atmospheric data crucial to future NASA exploration of the ice giant.

These investigations were possible because the large number of partners provided many unique views of the stellar occultation from many different instruments.

Emma Dahl, a postdoctoral scholar at Caltech in Pasadena, California, assisted in gathering observations from NASA's Infrared Telescope Facility (IRTF) on the summit of Mauna Kea in Hawaii - an observatory first built to support NASA's Voyager missions.

"As scientists, we do our best work when we collaborate. This was a team effort between NASA scientists, academic researchers, and amateur astronomers," said Dahl. "The atmospheres of the gas and ice giant planets [Jupiter, Saturn, Uranus, and Neptune] are exceptional atmospheric laboratories because they don't have solid surfaces. This allows us to study cloud formation, storms, and wind patterns without the extra variables and effects a surface produces, which can complicate simulations very quickly."

On November 12, 2024, NASA Langley researchers and collaborators were able to do a test run to prepare for the April occultation. Langley coordinated two telescopes in Japan and one in Thailand to observe a dimmer Uranus stellar occultation only visible from Asia. As a result, these observers learned how to calibrate their instruments to observe stellar occultations, and NASA was able to test its theory that multiple observatories working together could capture Uranus' big event in April.

Researchers from the Paris Observatory and Space Science Institute, in contact with NASA, also coordinated observations of the November 2024 occultation from two telescopes in India. These observations of Uranus and its rings allowed the researchers, who were also members of the April 7 occultation team, to improve the predictions about the timing on April 7 down to the second and also improved modeling to update Uranus' expected location during the occultation by 125 miles.

Uranus is almost 2 billion miles away from Earth and has an atmosphere composed of primarily hydrogen and helium. It does not have a solid surface, but rather a soft surface made of water, ammonia, and methane. It's called an ice giant because its interior contains an abundance of these swirling fluids that have relatively low freezing points. And, while Saturn is the most well-known planet for having rings, Uranus has 13 known rings composed of ice and dust.

Over the next six years, Uranus will occult several dimmer stars. NASA hopes to gather airborne and possibly space-based measurements of the next bright Uranus occultation in 2031, which will be of an even brighter star than the one observed in April.

]]> Fri, 23 MAY 2025 02:09:15 AEST Berkeley CA (SPX) Apr 16, 2025 - Imagine a Slushee composed of ammonia and water encased in a hard shell of water ice. Now picture these ice-encrusted slushballs, dubbed "mushballs," raining down like hailstones during a thunderstorm, illuminated by intense flashes of lightning.

Planetary scientists at the University of California, Berkeley, now say that hailstorms of mushballs accompanied by fierce lightning actually exist on Jupiter. In fact, mushball hailstorms may occur on all gaseous planets in the galaxy, including our solar system's other giant planets, Saturn, Uranus and Neptune.

The idea of mushballs was initially put forth in 2020 to explain nonuniformities in the distribution of ammonia gas in Jupiter's upper atmosphere that were detected both by NASA's Juno mission and by radio telescopes on Earth.

At the time, UC Berkeley graduate student Chris Moeckel and his adviser, Imke de Pater, professor emerita of astronomy and of earth and planetary science, thought the theory too elaborate to be real, requiring highly specific atmospheric conditions.

"Imke and I both were like, 'There's no way in the world this is true,'" said Moeckel, who received his UC Berkeley Ph.D. last year and is now a researcher at UC Berkeley's Space Sciences Laboratory. "So many things have to come together to actually explain this, it seems so exotic. I basically spent three years trying to prove this wrong. And I couldn't prove it wrong."

The confirmation, reported March 28 in the journal Science Advances, emerged together with the first 3D visualization of Jupiter's upper atmosphere, which Moeckel and de Pater recently created and describe in a paper that is now undergoing peer review and is posted on the preprint server arXiv.

The 3D picture of Jupiter's troposphere shows that the majority of the weather systems on Jupiter are shallow, reaching only 10 to 20 kilometers below the visible cloud deck or "surface" of the planet, which has a radius of 70,000 km. Most of the colorful, swirling patterns in the bands that encircle the planet are shallow.

Some weather, however, emerges much deeper in the troposphere, redistributing ammonia and water and essentially unmixing what was long thought to be a uniform atmosphere. The three types of weather events responsible are hurricane-like vortices, hotspots coupled to ammonia-rich plumes that wrap around the planet in a wave-like structure, and large storms that generate mushballs and lightning.

"Every time you look at Jupiter, it's mostly just surface level," Moeckel said. "It's shallow, but a few things - vortices and these big storms - can punch through."

"Juno really shows that ammonia is depleted at all latitudes down to about 150 kilometers, which is really odd," said de Pater, who discovered 10 years ago that ammonia was depleted down to about 50 km. "That's what Chris is trying to explain with his storm systems going much deeper than we expected."

Inferring planet composition from observations of clouds

"We're basically showing that the top of the atmosphere is actually a pretty bad representative of what is inside the planet," Moeckel said.

That's because storms like those that create mushballs unmix the atmosphere so that the chemical composition of the cloud tops does not necessarily reflect the composition deeper in the atmosphere. Jupiter is unlikely to be unique.

"You can just extend that to Uranus, Neptune - certainly to exoplanets as well," de Pater said.

The atmosphere on Jupiter is radically different from that on Earth. It's primarily made of hydrogen and helium gas with trace amounts of gaseous molecules, like ammonia and water, which are heavier than the bulk atmosphere. Earth's atmosphere is mainly nitrogen and oxygen. Jupiter also has storms, like the Great Red Spot, that last for centuries. And while ammonia gas and water vapor rise, freeze into droplets, like snow, and rain down continually, there is no solid surface to hit. At what point do the raindrops stop falling?

"On Earth, you have a surface, and rain will eventually hit this surface," Moeckel said. "The question is: What happens if you take the surface away? How far do the raindrops fall into the planet? This is what we have on the giant planets."

That question has piqued the interest of planetary scientists for decades, because processes like rain and storms are thought to be the main vertical mixers of planetary atmospheres. For decades, the simple assumption of a well-mixed atmosphere guided inferences about the interior makeup of gas giant planets like Jupiter.

Observations by radio telescopes, much of it conducted by de Pater and colleagues, show that this simple assumption is false.

"The turbulent cloud tops would lead you to believe that the atmosphere is well mixed," said Moeckel, invoking the analogy of a boiling pot of water. "If you look at the top, you see it boiling, and you would assume that the whole pot is boiling. But these findings show that even though the top looks like it's boiling, below is a layer that really is very steady and sluggish."

The microphysics of mushballs

But radio observations by Juno traced the regions of poor mixing to much greater depths, down to about 150 km, with many areas puzzlingly depleted of ammonia and no known mechanism that could explain the observations. This led to proposals that water and ammonia ice must form hailstones that fall out of the atmosphere and remove the ammonia. But it was a mystery how hailstones could form that were heavy enough to fall hundreds of kilometers into the atmosphere.

To explain why ammonia is missing from parts of Jupiter's atmosphere, planetary scientist Tristan Guillot proposed a theory involving violent storms and slushy hailstones called mushballs. In this idea, strong updrafts during storms can lift tiny ice particles high above the clouds - more than 60 kilometers up. At those altitudes, the ice mixes with ammonia vapor, which acts like antifreeze and melts the ice into a slushy liquid. As the particles continue to rise and fall, they grow larger - like hailstones on Earth - eventually becoming mushballs the size of softballs.

These mushballs can trap large amounts of water and ammonia with a 3 to 1 ratio. Because of their size and weight, they fall deep into the atmosphere - well below where the storm started - carrying the ammonia with them. This helps explain why ammonia appears to be missing from the upper atmosphere: it's being dragged down and hidden deep inside the planet, where it leaves faint signatures to be observed with radio telescopes.

However, the process depends on a number of specific conditions. The storms need to have very strong updrafts, around 100 meters per second, and the slushy particles must quickly mix with ammonia and grow large enough to survive the fall.

"The mushball journey essentially starts about 50 to 60 kilometers below the cloud deck as water droplets. The water droplets get rapidly lofted all the way to the top of the cloud deck, where they freeze out and then fall over a hundred kilometers into the planet, where they start to evaporate and deposit material down there," Moeckel said. "And so you have, essentially, this weird system that gets triggered far below the cloud deck, goes all the way to the top of the atmosphere and then sinks deep into the planet."

Unique signatures in the Juno radio data for one storm cloud convinced him and his colleagues that this is, indeed, what happens.

"There was a small spot under the cloud that either looked like cooling, that is, melting ice, or an ammonia enhancement, that is, melting and release of ammonia," Moeckel said. "It was the fact that either explanation was only possible with mushballs that eventually convinced me."

The radio signature could not have been caused by water raindrops or ammonia snow, according to paper co-author Huazhi Ge, an expert in cloud dynamics on giant planets and a postdoctoral fellow at the California Institute of Technology in Pasadena.

"The Science Advances paper shows, observationally, that this process apparently is true, against my best desire to find a simpler answer," Moeckel said.

Coordinated observations of Jupiter

"I essentially developed a tomography method that takes the radio observations and turns them into a three-dimensional rendering of that part of the atmosphere that is seen by Juno," Moeckel said.

The 3D picture of that one swath of Jupiter confirmed that most of the weather is happening in the upper 10 kilometers.

"The water condensation layer plays a crucial role in controlling the dynamics and the weather on Jupiter," Moeckel said. "Only the most powerful storms and waves can break through that layer.

Moeckel noted that his analysis of Jupiter's atmosphere was delayed by the lack of publicly available calibrated data products from the Juno mission. Given the current level of data released, he was forced to independently reconstruct the mission team's data processing methods - tools, data and discussions that, if shared earlier, could have significantly accelerated independent research and broadened scientific participation. He has since made these resources publicly available to support future research efforts.

Research Report:Tempests in the Troposphere: Mapping the Impact of Giant Storms on Jupiter's Deep Atmosphere

]]> Fri, 23 MAY 2025 02:09:15 AEST Los Angeles CA (SPX) Apr 01, 2025 - The ice giant Uranus, known for its peculiar sideways rotation, has revealed new atmospheric secrets thanks to a 20-year observational campaign using NASA's Hubble Space Telescope. Through precise imaging and spectral data collected over two decades, researchers have mapped long-term atmospheric dynamics and composition changes that offer key insights into this distant world.

This extensive dataset has allowed scientists to assess how Uranus's atmosphere responds to its unique solar exposure, improving models of how similar exoplanets might behave. Hubble's long operational life and powerful imaging tools made these discoveries possible, providing astronomers with a valuable reference for understanding ice giants beyond our solar system.

Voyager 2's 1986 flyby captured a static, featureless image of Uranus, likening it to a smooth, blue-green billiard ball. In contrast, Hubble's continued monitoring from 2002 to 2022 has detailed seasonal atmospheric changes. Led by Erich Karkoschka from the University of Arizona and Larry Sromovsky and Pat Fry from the University of Wisconsin, the team used Hubble's Space Telescope Imaging Spectrograph (STIS) to study Uranus during four observation periods.

These sessions revealed that methane is unevenly distributed in the planet's atmosphere. Specifically, methane concentrations are significantly lower near both poles, a pattern that remained stable across the two-decade timeframe. Meanwhile, haze and aerosol levels shifted dramatically, especially in the northern polar region, which brightened as the planet moved toward its northern summer solstice, expected in 2030.

Uranus orbits the Sun every 84 Earth years. Over the 20 years of observations, the planet progressed from northern spring toward summer, allowing scientists to observe only a portion of its solar cycle. Data from Hubble indicate dynamic atmospheric circulation, with descending air in polar regions and rising air in other latitudes, reshaping how scientists understand ice giant weather systems.

The research team compiled their findings through visual and spectral analyses, comparing Uranus's appearance and chemical structure across the four time points. Images captured in visible light display the planet as it would appear to the naked eye, while enhanced false-color composites in visible and near-infrared light highlighted varying levels of aerosols and methane.

Green hues indicated reduced methane, while red marked methane-free areas, particularly near the planet's edge, where the stratosphere is largely depleted of the gas. Further spectral mapping across 1,000 wavelengths revealed fine latitude-level structures in cloudiness and methane presence.

At middle and lower latitudes, both aerosols and methane concentrations exhibited consistent banding that changed little over time. However, at higher latitudes, particularly near the poles, aerosols and methane behaved differently. Aerosol levels near the north pole surged dramatically from dark to bright over the years, suggesting increased haze due to growing sunlight exposure. Conversely, methane depletion remained persistently strong in both polar zones.

These findings provide compelling evidence that solar radiation alters the aerosol haze on Uranus while having limited impact on methane levels. As Uranus nears its 2030 northern summer solstice, astronomers plan to continue using Hubble and other tools to monitor further atmospheric changes.

]]> Fri, 23 MAY 2025 02:09:15 AEST Los Angeles CA (SPX) Mar 10, 2025 - A team of astronomers analyzing data from NASA's Hubble Space Telescope and the W. M. Keck Observatory in Hawaii has likely discovered a rare three-body system in the Kuiper Belt. If confirmed, this would mark only the second such system found in the distant region of icy bodies beyond Neptune, suggesting that similar formations may be more common than previously thought.

The 148780 Altjira system, located approximately 3.7 billion miles from the Sun, appears to consist of three gravitationally bound objects. This discovery supports the hypothesis that some Kuiper Belt objects (KBOs) formed through direct gravitational collapse rather than through collisions.

"The universe is filled with a range of three-body systems, including the closest stars to Earth, the Alpha Centauri star system, and we're finding that the Kuiper Belt may be no exception," said study lead author Maia Nelsen, a physics and astronomy graduate from Brigham Young University in Provo, Utah.

KBOs, first identified in 1992, are remnants from the early solar system. Over 3,000 have been cataloged, with estimates suggesting that hundreds of thousands more, each over 10 miles in diameter, remain undiscovered. The largest known KBO is Pluto.

The Hubble observations indicate that the two primary objects in the Altjira system orbit approximately 4,700 miles (7,600 kilometers) apart. However, precise tracking of their movements suggests that what appears to be a single inner body is actually two objects so close together that they cannot be distinguished at this distance.

"With objects this small and far away, the separation between the two inner members of the system is a fraction of a pixel on Hubble's camera, so you have to use non-imaging methods to discover that it's a triple," explained Nelsen.

Researchers have spent 17 years observing Altjira with Hubble and Keck, tracking the motion of the outermost object. Their findings indicate that the inner object is not singular but either a very elongated body or two distinct objects in close orbit.

"Over time, we saw the orientation of the outer object's orbit change, indicating that the inner object was either very elongated or actually two separate objects," said Darin Ragozzine, a co-author of the study from Brigham Young University. "A triple system was the best fit when we put the Hubble data into different modeling scenarios."

Previously, only about 40 binary KBOs had been identified. With the addition of two probable three-body systems, scientists believe these triples may not be anomalies but rather part of a larger, yet-undiscovered population. However, confirming this requires ongoing observations.

The Kuiper Belt remains largely unexplored, with NASA's New Horizons spacecraft providing the only close-up views of its objects. The spacecraft flew past Pluto in 2015 and the smaller Arrokoth in 2019, revealing the latter to be a "contact binary" where two objects have merged or are in direct contact. Scientists believe Altjira, which is 10 times larger than Arrokoth at approximately 124 miles (200 kilometers) across, may share a similar formation history.

While no missions are currently planned to visit Altjira, its current "eclipsing season" provides a valuable opportunity for further study. Over the next decade, its outer body will pass in front of the central body, allowing researchers to analyze the system in greater detail.

"Altjira has entered an eclipsing season, where the outer body passes in front of the central body. This will last for the next ten years, giving scientists a great opportunity to learn more about it," Nelsen noted.

NASA's James Webb Space Telescope will contribute additional observations in its upcoming Cycle 3 study to determine whether Altjira's components exhibit similar characteristics.

Research Report:Beyond Point Masses. IV. Trans-Neptunian Object Altjira Is Likely a Hierarchical Triple Discovered through Non-Keplerian Motion

]]> Fri, 23 MAY 2025 02:09:15 AEST Los Angeles CA (SPX) Feb 26, 2025 - On March 1, NASA's Europa Clipper will execute a close flyby of Mars, passing just 550 miles (884 kilometers) above the planet's surface. This maneuver, known as a gravity assist, will adjust the spacecraft's trajectory and prepare it for a crucial stage in its journey toward Jupiter's icy moon, Europa. In addition to refining its path, the flyby presents an opportunity for mission scientists to test the spacecraft's radar and thermal imaging instruments.

At its closest approach to Mars at 12:57 p.m. EST, Europa Clipper will be moving at approximately 15.2 miles per second (24.5 kilometers per second) relative to the Sun. The gravity of Mars will gradually alter the spacecraft's trajectory over a span of 24 hours, effectively slowing it down and reshaping its solar orbit. After the encounter, Europa Clipper will depart at around 14 miles per second (22.5 kilometers per second).

This flyby is a key milestone, setting up the spacecraft for its next gravity assist with Earth in December 2026. That maneuver will provide an additional velocity boost, sending Europa Clipper on a direct course toward Jupiter, where it is expected to arrive in April 2030.

"We come in very fast, and the gravity from Mars acts on the spacecraft to bend its path," explained Brett Smith, a mission systems engineer at NASA's Jet Propulsion Laboratory (JPL) in Southern California. "Meanwhile, we're exchanging a small amount of energy with the planet, so we leave on a path that will bring us back past Earth."

Utilizing Gravity for Efficiency

NASA has long relied on gravity assists to optimize space missions. The Voyager 1 and Voyager 2 spacecraft, launched in 1977, used a rare planetary alignment to slingshot past multiple gas giants, capturing unprecedented data along the way. JPL engineers, who oversee Europa Clipper and the Voyager missions, carefully calculate planetary positions and spacecraft trajectories to maximize efficiency.

"It's like a game of billiards around the solar system, flying by a couple of planets at just the right angle and timing to build up the energy we need to get to Jupiter and Europa," said Ben Bradley, Europa Clipper mission planner at JPL. "Everything has to line up-the geometry of the solar system has to be just right to pull it off."

Fine-Tuning the Flight Path

Three TCMs have already been executed-in early November, late January, and on February 14-to refine the spacecraft's trajectory. Following the Mars flyby, another TCM will take place roughly 15 days later to ensure the spacecraft remains on course. Throughout the mission, controllers may conduct as many as 200 TCMs to maintain accuracy and efficiency as Europa Clipper travels toward its final destination.

Scientific Opportunity at Mars

Near closest approach, the mission team will also conduct the first full test of the spacecraft's radar system. The radar's large antennas and long wavelengths made ground-based testing before launch impractical, making this flyby a valuable opportunity to verify their operation in space.

]]> Fri, 23 MAY 2025 02:09:15 AEST Washington DC (UPI) Feb 23, 2025 - A shell of icy objects at the edge of the solar system known as the Oort cloud has a pair of spiral arms that resemble a miniature galaxy, new research suggests.

Until now, the shape of the cloud and how it is affected by forces beyond our solar system have not been largely understood. But the new research, published Feb. 16 at arXiv, says the cloud may look like a spiral disk, one of the key characteristics necessary to be called an independent galaxy. The work has not yet been peer-reviewed.

The Oort cloud was born out of remnants of the solar system's giant planets, Jupiter, Neptune, Uranus and Saturn, after they formed 4.6 billion years ago. Some of the remnants are so large that some scientists consider them dwarf planets.

The Oort cloud's inner edge sits as far as 5,000 astronomical units from the sun, and its outer edge is as far as 100,000 AU away. One AU is 93 million miles, the average distance from Earth to the sun. So, depending on the actual distance, NASA's Voyager 1 spacecraft, which is traveling a million miles a day, won't reach the edge of the Oort cloud for 300 years and won't exit it for another 300,000.

The bodies in the cloud are so small and faint when measured with Earth-based technology, the researchers who did the new study used data gathered from the orbits of comets and gravitational forces from within and beyond our solar system to create a model of the Oort cloud's structure. They are trying to better understand the makeup and origins of the Oort cloud because it could shed some light on the history of our solar system's formation.

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