All posts tagged: Solar System

New evidence challenges the idea that Earth and Mars formed the same way

New evidence challenges the idea that Earth and Mars formed the same way

Published by Jenni Sidey

Earth and Mars may have formed through surprisingly different mixtures of pebble accretion, planetesimal collisions and giant impacts, despite growing beside each other in the same young Solar System. Chemical modeling suggests at least 75% of Earth’s mass came from two protoplanets that grew mainly by capturing pebbles, while roughly 73% of Mars came from volatile-depleted planetesimals. The study uses the loss of moderately volatile elements as a record of planetary growth, providing a possible new way to reconstruct the formation and habitability of rocky worlds around other stars. Earth and Mars emerged from the same swirling disk of gas and dust, separated today by less than 80 million kilometers at their closest approach. Their common birthplace might suggest that the two rocky planets were assembled through broadly similar processes. Their chemistry tells a different story. A University of Copenhagen-led study finds that Earth appears to have been built primarily from large protoplanets that themselves grew by sweeping up millimeter- to centimeter-sized pebbles. Mars, by contrast, acquired most of its mass from collisions with much …

NASA discovers a once-in-a-century impact blasted a 728-foot crater into the Moon

NASA discovers a once-in-a-century impact blasted a 728-foot crater into the Moon

Published by Jenni Sidey

NASA’s Lunar Reconnaissance Orbiter revealed a 222-meter-wide crater that formed on the Moon between April 11 and May 22, 2024, making it the largest newly formed impact crater directly identified anywhere in the Solar System. The impact blasted material across the surrounding terrain, disturbed the surface more than 120 kilometers away and created a roughly 4-mile-wide nighttime “cold spot.” Scientists estimate an impact this large occurs on the Moon only about once every 132 years, giving researchers a rare opportunity to study crater formation almost immediately after it happened. A routine comparison of old and new Moon maps exposed something that should not have been there. Robert Wagner, an image-processing specialist working with NASA’s Lunar Reconnaissance Orbiter Camera system, noticed an unusually large bright patch surrounded by a dark halo. When he compared newer images with older ones, the explanation became clear: something had slammed into the Moon and excavated a crater hundreds of feet across. The feature, now named McGetchin crater, formed sometime between April 11 and May 22, 2024. At about 222 meters, …

JWST finds evidence that Chariklo’s rings are changing faster than astronomers expected

JWST finds evidence that Chariklo’s rings are changing faster than astronomers expected

Published by Jenni Sidey

James Webb Space Telescope observations show Chariklo’s inner ring has become markedly more opaque while its fainter outer ring appears less opaque than in earlier occultations. JWST’s unusually slow passage relative to Chariklo provided spatial resolution of roughly 750 meters, allowing astronomers to probe structures too narrow to image directly. Researchers cannot yet determine whether the changes reflect real movement or redistribution of ring material, wavelength effects, or a combination of both. A pair of narrow rings circling a small world between Saturn and Uranus no longer looks as stable as astronomers once thought. Observations from the James Webb Space Telescope show that Chariklo’s dense inner ring became substantially more opaque compared with measurements from previous years. At the same time, its much fainter outer ring appeared to lose opacity. The changes emerged from a stellar occultation observed on Oct. 18, 2022, when Chariklo’s rings crossed in front of a distant star. Researchers led by the Institute of Astrophysics of Andalusia, or IAA-CSIC, compared the JWST measurements with occultations obtained during the previous decade. Their …

A missing super-Earth may have been swallowed up by the Sun billions of years ago

A missing super-Earth may have been swallowed up by the Sun billions of years ago

Published by Jenni Sidey

New solar-evolution models suggest the young Sun may have swallowed a rocky super-Earth, leaving a chemical fingerprint beneath its convection zone that could still affect the Sun’s internal structure today. The best-fitting models favor an engulfed planet in the super-Earth range, with several solutions pointing to roughly 5 to 10 Earth masses while simultaneously improving agreement with helioseismic measurements and the Sun’s unusually low lithium abundance. The scenario remains a hypothesis rather than evidence that a lost planet definitely existed, but calculations indicate a compact rocky world could penetrate deeply into the young Sun without being destroyed by ordinary aerodynamic ablation alone. The solar system may once have contained a world several times larger than Earth that no longer exists. Rather than being ejected into interstellar space or colliding with another planet, it may have disappeared inside the Sun. A new modeling study suggests such an event could have left a chemical fingerprint deep enough inside our star to survive for billions of years. Researchers found that adding the engulfment of a super-Earth to models …

Tidal forces may have doomed an ancient moon around Venus

Tidal forces may have doomed an ancient moon around Venus

Published by Jenni Sidey

A hypothetical moon around early Venus could initially have migrated outward, only for tidal evolution to reverse its path and send it crashing back toward the planet. The moon’s fate depends strongly on Venus’s original spin, the satellite’s mass, orbital eccentricity and how the planet’s rocky interior dissipated tidal energy. The models do not show that Venus ever possessed a moon, but they demonstrate that its absence today does not rule out an ancient satellite that was destroyed billions of years ago. Venus has no moon today, but that emptiness may not tell the whole story of the planet’s violent youth. A new theoretical study finds that a substantial satellite created by an ancient impact could have spent millions or even billions of years orbiting Venus before tides reversed its migration. The moon could then have spiraled inward, crossed the planet’s Roche limit, broken apart into a temporary ring and eventually rained much of its material onto Venus. The work, led by University of California, Riverside astronomer Stephen Kane with Franck Selsis, Jeremy Leconte and …

Cosmic collision: The Milky Way once flipped by more than 90 degrees

Cosmic collision: The Milky Way once flipped by more than 90 degrees

Published by Jenni Sidey

The Milky Way may not always have faced the same direction. New simulations suggest its stellar disc could have swung through space by more than 90 degrees after an ancient collision, helping explain why the galaxy’s surrounding halo turns so slowly. Most stars in the Milky Way, including the Sun, occupy its flat spiral disc. Far beyond that structure lies a much larger stellar halo. It contains relatively few stars, many of which formed inside smaller galaxies before mergers drew them into the Milky Way. A Durham University team examined 25 Milky Way-like galaxies in the Auriga suite of cosmological simulations. These models followed galactic growth across billions of years, including collisions, mergers and changes in stellar motion. Artist’s impression of debris of the Gaia-Enceladus galaxy. (CREDIT: ESA (artist’s impression and composition); Koppelman, Villalobos and Helmi (simulation) / CC BY-SA 3.0 IGO) The galaxies with the slowest rotating stellar haloes shared two traits. Each had experienced a major head-on merger, and each had undergone what astronomers call a disc flip. A galaxy can change its …

The most detailed survey of the universe ever conducted starts now

The most detailed survey of the universe ever conducted starts now

Published by skeptic

A field of stars in the constellation Lupus captured by the Vera C. Rubin Observatory NSF–DOE Vera C. Rubin Observatory/NOIRLab/SLAC​/AURA The Vera C. Rubin Observatory in Chile is finally beginning its mammoth survey of the universe. After a year of testing and calibration, it is starting the Legacy Survey of Space and Time, which is poised to become the most detailed record of the universe ever captured. “Today, we begin filming the greatest cosmic movie ever made,” said Brian Stone at the US National Science Foundation in a statement. For the next decade, Rubin will collect about 10 terabytes of data every night in the form of hundreds of high-resolution images of the southern sky. Each image will cover an area about 40 times the size of the full moon, and the completed survey will include nearly the entirety of the sky that is visible from the southern hemisphere. This treasure trove of data will serve several purposes. The first, which has already begun, is to alert researchers to anything changing in the night sky, …

Earth may not be swallowed by our dying sun after all, study finds

Earth may not be swallowed by our dying sun after all, study finds

Published by Jenni Sidey

For a long time, Earth’s ending seemed settled. In about five billion years, the sun will swell into a giant, the inner Solar System will be transformed, and our planet was widely expected to be consumed in the process. But that picture may not be as final as once thought. New calculations suggest Earth might avoid being swallowed by the expanding sun, surviving both of the star’s giant late-life growth phases. The outcome is still uncertain, and no version of the future leaves Earth livable. But the work shifts a question many astronomers thought was nearly closed. The tension comes down to two competing effects. As the sun ages and expands beyond its current main-sequence phase, it will first enter the red giant branch, then later the asymptotic giant branch, or AGB. During both stages, the star will balloon outward and lose mass through a strong stellar wind. Those two changes tug planets in opposite directions. Expanding stars raise tides that can drain orbital energy and pull planets inward. At the same time, mass loss …

We’ve found a mysterious substance on Titan and Pluto

We’ve found a mysterious substance on Titan and Pluto

Published by skeptic

Titan in ultraviolet and infrared wavelengths, as captured by the Cassini probe in 2004 NASA/JPL/Space Science Institute A strange substance is hiding on the surfaces of both Pluto and Saturn’s moon Titan, and researchers aren’t sure what it is. Titan’s thick atmosphere means it is extremely difficult to study its surface, so identifying this compound may help us understand the complex chemistry happening there. This moon is one of the most intriguing places in the solar system to search for alien life, and figuring out its chemistry is key to that search. Astronomers study what distant worlds are made of using spectroscopy: analysing the wavelengths of light that are absorbed, reflected or emitted by chemicals. Bruno Bézard at the Paris Observatory and his colleagues found the compound using data from the James Webb Space Telescope (JWST). They found a narrow-wavelength band of light being absorbed by something on Titan’s surface, and the same wavelengths of light – although with a broader spread – being absorbed on Pluto. On the face of it, the two worlds …

Gas from Uranus reveals it has an icy centre

Gas from Uranus reveals it has an icy centre

Published by skeptic

What lies at the centre of Uranus? JPL/NASA Uranus appears to have far more water frozen as ice in its interior than astronomers thought, potentially settling a long-running mystery about whether it formed differently to its closest neighbour, Neptune. Ice giants like Uranus and Neptune have thick, gassy atmospheres. This makes it hard to know what is inside the planets’ interiors or how they formed. Scientists can, however, measure gases in their atmospheres, which they can then link to processes and elements deeper inside. Carbon monoxide in a planet’s atmosphere is often associated with its deepest parts being rich in water or ice, but while neighbouring Neptune has displayed abundant carbon monoxide suggestive of an ice-rich centre, Uranus has been lacking, which has led some astronomers to argue it instead has a rocky interior. If true, this would mean that Neptune and Uranus formed in very different ways and aren’t as similar as they appear. Now, Thibault Cavalié at the University of Bordeaux in France and his colleagues have found carbon monoxide in Uranus’s lower …