Mercury Archives

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.

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 […]

An artist's concept illustrates a dusty planet-forming disk -- NASA

Astrochemistry, Astrogeology, Exoplanets, -moons, -comets, Mars, Mercury, Meteorites & Asteroids, Status Report, Venus

Homogeneous Accretion Of The Earth In The Inner Solar System

by Keith CowingApril 17, 2026April 17, 2026

Meteorites are classified as either non-carbonaceous- (NC) or carbonaceous (CC), representing bodies that likely formed in the inner- or outer solar system, respectively. Despite its location in the inner solar […]

An artist's depiction of a planet, represented by the black circle, orbiting a pair of stars — a so-called binary star system. (Image Credit: NASA/Goddard Space Flight Center)

Astronomy & Telescopes, Exoplanets, -moons, -comets, Press Release, Science Fiction, Stellar Cartography

Why Are Tatooine Planets Rare? Blame General Relativity

by Keith CowingJanuary 30, 2026January 30, 2026

Of the more than 4,500 stars known to have planets, one puzzling statistic stands out. Even though nearly all stars are expected to have planets and most stars form in […]

The result of 100 successful simulations of the back20 model (the ring at 0.85 au with a 20% background) that produced a good match to all terrestrial planets (as defined in Section 3.1). The black dots show the results of individual simulations with good final planets. The bigger red dots are the real planets. Note that we do not exclude simulations that produced additional bodies with m < 0.05 MEarth in the Mars region (1.2 < a < 1.8 au). Some of these bodies would collide with Mars at t > 200 Myr (these simulations were terminated at 200 Myr). -- astro-ph.EP

Astrogeology, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Impact events, Status Report

Terrestrial Planet Formation From Two Source Reservoirs

by Keith CowingJuly 22, 2025July 22, 2025

This work describes new dynamical simulations of terrestrial planet formation. The simulations started at the protoplanetary disk stage, when planetesimals formed and accreted into protoplanets, and continued past the late […]

Eccentricity and position snapshots over time of a simulation using the mixed scenario where all 4 terrestrial planets fit constraints and the Earth analogue had a final CC embryo impact. Snapshots are shown over time, including the moment after the final giant impact. The initial NC embryos and planetesimals are shown with the embryos in black and the planetesimals in orange, as well as the CC embryos and planetesimals in blue with Jupiter and Saturn in black on the far right. The final snapshot is the real solar system. -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Extinction events, Impact events, Mars, Mercury, Moon, Status Report, Venus

Dynamical Origin Of Theia, The Last Giant Impactor On Earth

by Keith CowingJuly 4, 2025July 4, 2025

Cosmochemical studies have proposed that Earth accreted roughly 5-10% of its mass from carbonaceous (CC) material, with a large fraction delivered late via its final impactor, Theia (the Moon-forming impactor). […]

Impact history should play a crucial role in the search for habitable exoplanets like Earth -- SwRI

Astrochemistry, Astrogeology, Exoplanets, -moons, -comets, Impact events, Lava / magma ocean / Volcanic Worlds, Mars, Mercury, Press Release, Venus

Notable Progress In Understanding The Evolution Of The Terrestrial Planets

by Keith CowingJune 18, 2025June 18, 2025

An SwRI-led team compared the early impact history of Venus and Earth, determining that Venus experienced higher-energy impacts that created a superheated core. Models show these conditions could create Venus’ […]

Schematic view of the interior of terrestrial planets showing major chemical layers (i.e., the crust, the mantle, and the core subdivided into an outer liquid and an inner solid core). For each terrestrial planet the surface elevation is shown with the same color scale for comparison using orthographic projection. -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Mars, Mercury, Moon, Status Report, Venus

Terrestrial Planet Surfaces And Interiors

by Keith CowingNovember 19, 2024November 19, 2024

Rocky planets in our Solar System, namely Mercury, Venus, Earth, Mars, and the Moon, which is generally added to this group due to its geological complexity, possess a solid surface […]

Sulfur distribution on the surface of Mercury expressed as S/Si (Nittler et al., 2020). The highest S abundances 90 degrees west at the equator and north of it coincides with the highest Ca and Mg abundances, referred to as the high magnesium region (HMR) (reproduced from Nittler et al., 2020). -- astro-ph.EP

Astrochemistry, Astrogeology, Lava / magma ocean / Volcanic Worlds, Mapping, Geodesy, Cartography, Bathymetry, Mercury, Moon, Status Report

Sulfur In The Moon And Mercury

by Keith CowingOctober 29, 2024October 29, 2024

This chapter presents a comprehensive overview of the abundances and distribution of S, and the processes that control the behavior of S on the Earth’s Moon and on Mercury. The […]

Artist’s rendition of variety of exoplanets featured in the new NASA TESS-Keck Survey Mass Catalog, the largest, single, homogenous analysis of TESS planets released by any survey thus far. Credit: W. M. Keck Observatory/Adam Makarenko

Alpha Centauri, Astrogeology, Beta Pictoris, Ceres, Exoplanets, -moons, -comets, Gas Giants, Icy Worlds, Jupiter, Lava / magma ocean / Volcanic Worlds, Mapping, Geodesy, Cartography, Bathymetry, Mars, Mercury, Neptune, Pluto, Proxima Centauri, Saturn, Status Report, tau Ceti, TRAPPIST-1, Uranus, Venus, Water/Hycean Worlds & Oceanography

Classifications For Exoplanet and Exoplanetary Systems

by Keith CowingSeptember 17, 2024September 17, 2024

When a star is described as a spectral class G2V, we know its approximate mass, temperature, age, and size. At more than 5,700 exoplanets discovered, it is a natural developmental […]