Comets and Asteroids Archives

An X-ray image of NWA 12774. (Credit: Aaron Bell/CU Boulder)

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Comets and Asteroids, Impact events, Meteorites & Asteroids, Press Release, Sample Return

Rare Meteorite Provides Evidence Of A Giant Early Planet

by Keith CowingJune 17, 2026June 17, 2026

Four-and-a-half billion years ago, a massive world, possibly as big as the moon or even Mars, orbited our sun before crashing into another celestial body and shattering into rubble.

Locations of the four candidate sites across a 2D map projection of Bennu’s surface captured by the OSIRIS-REx Camera Suite (OCAMS) (Bennett et al., 2021).

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Comets and Asteroids, Imaging & Spectroscopy, Missions & Hardware, Sample Return, Status Report

Quantifying Surface Heterogeneity Across Asteroid (101955) Bennu using Candidate Site Remote Sensing Data

by Keith CowingJune 13, 2026June 13, 2026

The OSIRIS-REx mission acquired spatially resolved (2-10 m spot sizes) visible-near infrared (VNIR) and thermal infrared (TIR) spectra across four candidate sampling sites on asteroid (101955) Bennu: Nightingale, Osprey, Sandpiper, […]

Schematic illustrating the evolutionary stages of the Eulalia asteroid family. (a) The Eulalia parent body resides near the Jupiter 3:1 mean-motion resonance (J3:1). (b) Catastrophic disruption of the parent body occurs, with approximately 50% of the fragments being directly injected into the J3:1, where they can be driven into the planet-crossing region. (c) Post-disruption dynamical evolution, during which an estimated 50% of the surviving fragments are expected to eventually migrate toward the J3:1 resonance via Yarkovsky thermal forces. -- astro-ph.EP

Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Comets and Asteroids, Extinction events, Habitable Zones, Impact events, Meteorites & Asteroids, Status Report

An 800-Million-Year-Old Impact Shower on the Terrestrial Planets from the Breakup of the Eulalia Parent Body

by Keith CowingJune 7, 2026June 7, 2026

Multiple studies have proposed a substantial surge in large lunar impacts approximately 800 million years ago (Ma).

Initial structure of the Impact Plume 60 s post impact. The impactor strikes from the left, at a 60° angle from horizontal, with the sun located to the right.There is a visible asymmetry in the plume due to the direction of impact; the “hole” on the right side of the plume is a bubble in this 2D slice of a fully 3D plume due to the removal of water vapor-rock mixtures from the simulation during the sampling from SOVA into DSMC codes (Prem et al. 2015). (Top) the plume contains a region of high density (~1022 molecules/m3 ) just above the point of impact, which rapidly drops toward the edges of the plume. (Bottom, left) The high plume densities correspond to short mean free paths for the vapor molecules. (Bottom, right) Comparing this mean free path with the length scale of the density gradient reveals very small Knudsen numbers throughout; the entire plume (except for the very outermost edges) is clearly within the continuum flow regime at this time, rather than the slip-flow, Knudsen, or Free Molecular regimes. -- astro-ph.EP

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Comets and Asteroids, Cryobiology, Icy Worlds, Imaging & Spectroscopy, Impact events, Mapping, Geodesy, Cartography, Bathymetry, Mercury, Status Report

Transport of Water In A Transient, Impact-Generated Atmosphere On Mercury

by Keith CowingJune 5, 2026June 26, 2026

Mercury’s polar cold traps host water ice deposits that are likely populated with impact-delivered water via Mercury’s exosphere.

Allen Telescope Array (ATA) at the Hat Creek Radio Observatory in Northern California -- SETI Institute

Astrochemistry, Astronomy & Telescopes, Biosignatures & Paleobiology, Comets and Asteroids, Imaging & Spectroscopy, Intelligence & Language, Interstellar, Press Release, SETI & Technosignatures

SETI Institute Looks for Signs of Technology in Interstellar Visitor 3I/ATLAS

by Keith CowingJune 4, 2026June 4, 2026

Scientists at the SETI Institute searched for technological signals from 3I/ATLAS, the third interstellar object observed in our Solar System.

An artist's impression of a disk of gas and dust formed during the birth of the sun. Credit: NASA/FUSE/Lynette Cook

Astrochemistry, Astrogeology, Comets and Asteroids, Exoplanets, -moons, -comets, Habitable Zones, Mars, Mercury, Meteorites & Asteroids, Press Release, Venus

New Experiments And Modeling On Iron Meteorites Provide Insight Into Young Solar System And Earth’s Building Blocks

by Keith CowingJune 4, 2026June 4, 2026

Habitable planets require life-essential elements, like nitrogen and phosphorus. Understanding how those elements ended up in a planetary body can give insight into the formation of the solar system and […]

Top: coma maps of H2O, CO2, and CH4, computed as the molecular column density from a pixel-by-pixel retrieval analysis for Observations 6, 15, and 6, respectively. The sunward and target velocity directions are denoted by the white arrows. The target centroids, computed as the photocenter in the median-stacked images (Figure 1), are marked with the black points. For H2O and CO2, the white contours correspond to emission levels of 50% and 20% relative to the maximum value and illustrate the slight antisunward extension of the respective comae. The contours are omitted in the CH4 panel, due to the poorer signal-to-noise ratio of the data. Bottom: corresponding median-stacked images across the continuum wavelengths within each fluorescence region. The H2O coma map shows a significant enhancement in the emission level at large nucleocentric distances relative to the dust continuum, indicating extended H2O production within the coma. -- The Astrophysical Journal Letters

Astrochemistry, Astronomy & Telescopes, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Interstellar, Press Release

Webb Detects Methane on Interstellar Comet 3I/ATLAS

by Keith CowingJune 2, 2026June 2, 2026

NASA’s James Webb Space Telescope has collected its first mid-infrared chemical fingerprint of an interstellar object during a recent revisit to comet 3I/ATLAS. The team’s results published recently in The […]

Spectral characterization of Chiron’s surface composition. a Comparison of the bestfit spectral model of the surface composition (red) with the measured spectrum (black). The surface is best described by an intimate mixture of water ice in both amorphous and crystalline phases, carbon dioxide ice, and tholin-like materials. b Residuals between the model and the data show an excellent fit, with a root mean square deviation that is just 1% higher than the average scatter in the data. c Zoomed-in view of the complex organic absorption feature spanning 3.3–3.6 µm, with the individual component bands indicated by dashed lines. Comparison between the measured spectrum and synthetic spectra of several candidate species, convolved to the spectral resolution of the data, points to C3H8 and/or ice tholins produced by the irradiation of H2O ice and C2H6 as the most plausible candidates for the observed organic feature. -- astro-ph.EP

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Status Report

JWST Reveals Anomalously Enhanced Methane Outgassing From Below Chiron’s Water Ice And Carbon Dioxide Bearing Surface

by Keith CowingMay 26, 2026May 26, 2026

Centaurs are inward-scattered Kuiper belt objects, with some exhibiting comet-like activity. The physical mechanisms powering this activity remain poorly understood, with carbon monoxide (CO) sublimation or the crystallization of amorphous […]

Canister containing material collected from asteroid Bennu placed inside the OSIRIS-REx sample return capsule. Credit: NASA/GSFC/Univ. of Arizona/Lockheed Martin

Astrochemistry, Astrogeology, Biosignatures & Paleobiology, Comets and Asteroids, Missions & Hardware, Planetary Protection & Biosafety, Sample Return, Status Report

Asteroid Sample Return Missions Are Critical For Understanding Our Solar System

by Keith CowingMay 24, 2026May 24, 2026

Studying asteroids addresses a number of unknowns in planetary science. Investigating them makes use of asteroidal meteorites, remote observations and space-based missions.

Juice-UVS saw gas and dust elements stretching up to more than 5 million km from 3I/ATLAS’s nucleus on November 25, 2025, when the comet had dimmed considerably relative to November 2 observations. Black spots are where stars appeared in the scanned image, removed here for clarity. Credit: NASA/ESA/Southwest Research Institute

Astrochemistry, Astrogeology, Comets and Asteroids, Europa, Icy Worlds, Imaging & Spectroscopy, Missions & Hardware, Press Release

Two Spacecraft Observed Both Hemispheres Of Interstellar Comet 3I/ATLAS Simultaneously

by Keith CowingMay 14, 2026May 14, 2026

The Southwest Research Institute-led Ultraviolet Spectrograph (UVS) instruments aboard ESA’s Jupiter Icy Moons Explorer (Juice) spacecraft and NASA’s Europa Clipper made unique observations of interstellar comet 3I/ATLAS in late 2025. […]

Comets and Asteroids

Rare Meteorite Provides Evidence Of A Giant Early Planet

Quantifying Surface Heterogeneity Across Asteroid (101955) Bennu using Candidate Site Remote Sensing Data

An 800-Million-Year-Old Impact Shower on the Terrestrial Planets from the Breakup of the Eulalia Parent Body

Transport of Water In A Transient, Impact-Generated Atmosphere On Mercury

SETI Institute Looks for Signs of Technology in Interstellar Visitor 3I/ATLAS

New Experiments And Modeling On Iron Meteorites Provide Insight Into Young Solar System And Earth’s Building Blocks

Webb Detects Methane on Interstellar Comet 3I/ATLAS

JWST Reveals Anomalously Enhanced Methane Outgassing From Below Chiron’s Water Ice And Carbon Dioxide Bearing Surface

Asteroid Sample Return Missions Are Critical For Understanding Our Solar System

Two Spacecraft Observed Both Hemispheres Of Interstellar Comet 3I/ATLAS Simultaneously

Training For Astrobiology Spelunking On Mars

Mars Perseverance Rover’s Panoramic View of Broom Point

Planets Orbiting Barnard’s Star Seem To Be Small, Strange, And Utterly Uninhabitable

Experimental Astrochemistry And Machine Learning Unravel The Formation Of Oxygen-bearing Organic Molecules In Extraterrestrial Ices

Bacteria Form Herds To Survive Predators, Offering Fresh Insight Into Earth’s Carbon Cycle