Terrestrial Planet Archives

Astrogeology, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Desert Worlds, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Mars, Status Report

Coupling Dynamical Accretion And Chemical Differentiation: A Unified Framework For Earth-Mars Diversity

by Keith CowingJune 15, 2026June 15, 2026

The distinct physical and geochemical differences between Earth and Mars provide fundamental constraints on terrestrial planet formation, yet a self-consistent framework linking dynamical and chemical aspects remains elusive.

Comparison of input SEDs used in this study and molecular photoabsorption cross sections relevant to Archean-analog photochemistry. The horizontal bars indicate the FUV and NUV wavelength intervals used to compute the stellar FUV/NUV ratios in Figures 5 and 7. Top: Top-of-atmosphere (ToA) stellar energy fluxes at TRAPPIST-1 e from 120–350 nm for five SEDs: Peacock+2019 (P19) Median (orange) (S. Peacock et al. 2019), Mega-MUSCLES (W21) Adaptive (yellow), Mega-MUSCLES (W21) SEM (light blue) (D. J. Wilson et al. 2021), a “Revised PHOENIX” model (dark blue) constrained by the HST observations published in D. J. Wilson et al. (2021), and a scaled modern Sun (red) (G. Thuillier et al. 2004). All SEDs are scaled to TRAPPIST-1 e’s ToA irradiance. Bottom: Representative molecular cross sections for CH4 (pink), CO2 (black), H2O (green), O2 (light blue), and O3 (dark blue) are shown, highlighting the wavelength overlap between the cross sections and the stellar UV output. Where both the flux and the cross section are large, photolysis rates increase and influence production and loss pathways throughout the atmosphere. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Press Release, TRAPPIST-1

Ultraviolet-Driven Atmospheric Degeneracies Challenge Conventional Biosignature Frameworks for Terrestrial Planets with Ultracool M Dwarf Hosts: An Archean-Analog TRAPPIST-1 e Case Study

by Keith CowingJune 7, 2026June 7, 2026

The ultraviolet (UV) spectrum of a host star strongly shapes the atmospheric composition and potential biosignatures of its planets. This relationship may be especially important for the planets orbiting TRAPPIST-1, […]

The changing mantle FeO and SiO2 of 8 Earth analogues as they grow through the simulation. The black dashed line and the grey band show the BSE concentrations of FeO and SiO2 (Palme and O’Neill, 2003) and the uncertainties on these values. The left-hand figure contains an insert that allows for a clearer view of the point at which the embryo masses reach 1 Earth Mass. -- astro-ph.EP

Astrogeology, Exoplanets, -moons, -comets, Meteorites & Asteroids, Press Release

Oxidation Constraints On Terrestrial Planet Formation From A Ring

by Keith CowingJune 2, 2026June 2, 2026

The present-day solar system comprises meteorites with varying oxidation levels, derived from different parent bodies.

Comparison of ages for stars with at least one measurement from both asteroseismology and gyrochronology. For stars with only one measurement from either method, the reported age and statistical uncertainties are shown. Gyrochronology generally agrees with asteroseismology for younger stars, but underestimates stellar ages for stars significantly older than the Sun (∼ 4.6 Gyr). astro-ph.SR

Astronomy & Telescopes, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report, Stellar Cartography

The HAges Catalog: Stellar Ages For High Priority HWO Target Stars

by Keith CowingMay 15, 2026May 15, 2026

Precise stellar ages (uncertainties ≲1 Gyr, or ∼20% at solar age) are required to discern evolutionary trends in atmospheric biosignatures of terrestrial habitable zone exoplanets surveyed by the Habitable Worlds […]

TOP Ice states for HEXTOR calculations based on the THAI Hab 1 configuration, which show smooth transitions from ice-covered to cool dayside to warm dayside to ice-free states as instellation increases. These results do not depend on the choice of initialization temperature. BOTTOM Ice states for HEXTOR calculations based on the THAI Hab 1 configuration, across a parameter space of instellation and CO2 partial pressure. -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Gaia - Planetary Perspectives, Imaging & Spectroscopy, Status Report, TRAPPIST-1, Water/Hycean Worlds & Oceanography

Exploring TRAPPIST-1 Climate States With An Energy Balance Model

by Keith CowingMay 12, 2026May 12, 2026

This paper presents a version of the HEXTOR energy balance model that has been configured for the study of habitable terrestrial planets orbiting low-mass stars. The model is validated for […]

Model prediction for the water budget of the 4 terrestrial planets

Astrochemistry, Astrogeology, Biogeochemical Cycles & Geobiology, Habitable Zones, Mars, Mercury, Status Report, Venus

Astrochemical Inheritance of Terrestrial Planets Water from Local Wet Silicates

by Keith CowingMay 1, 2026May 5, 2026

The delivery of water to the inner Solar System rocky planets, including Earth, remains debated, as standard models assume that they formed from dry grains, inside the snowline of the […]

Height scales of atmospheres of Solar System’s terrestrial planets. The solid lines show the temperature profiles against altitude, while the background colour reflects the atmospheric pressure. Horizontal dashed lines denote the average positions of atmospheric boundaries: tropopause (“t”), stratopause (“s”), and mesopause (“m”). Vertical cyan lines depict the extension of ionospheres (“i”) under typical conditions. The “⊙” symbol denotes the 100 mbar level. -- Space Science Reviews via PubMed

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Gaia - Planetary Perspectives, Habitable Zones, Status Report

Upper Atmosphere Dynamics and Drivers of Volatiles Loss from Terrestrial-Type (Exo)Planets

by Keith CowingApril 6, 2026April 6, 2026

Volatile loss from exoplanetary atmospheres and its possible implications for the longevity of habitable surface conditions is a topic of vigorous debate currently.

This illustration shows an ultra-hot Jupiter orbiting a blue-white A-type star. Credit: International Gemini Observatory/NOIRLab/NSF/AURA/J. Pollard

Astrochemistry, Astronomy & Telescopes, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Interstellar, Press Release

Gemini South Confirms Long-Suspected Link Between the Composition of Exoplanets and Their Host Stars

by Keith CowingApril 4, 2026April 4, 2026

Almost 320 light-years away in the Libra constellation lies WASP-189b, an exoplanet known as an ultra-hot Jupiter (UHJ). UHJs have temperatures high enough to vaporize rock-forming elements like magnesium (Mg), […]

The left panel shows the relative astrometric orbit of 70 Oph B around 70 Oph A. Red points denote archival visual and micrometric measurements from the WDS/ORB6 catalog, while the solid black curve shows the maximum-likelihood joint orbital solution. 50 orbits color-coded by companion mass are randomly drawn from the posterior and plotted, but they are indistinguishable from the black curve because of the tight constraint on the orbit. The dashed line marks the line of nodes, and the star indicates the primary’s position. The right panel shows the RV variation of 70 Oph A measured by eight instruments. Colors correspond to individual RV datasets as indicated in the legend. Residuals relative to the best-fit model are shown. -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

A Century of Radial Velocity and Astrometric Monitoring of 70 Oph AB: New PFS Data and Constraints on Planetary Companions

by Keith CowingMarch 24, 2026March 24, 2026

At a distance of 5.1 pc, the 70 Oph AB binary star system is one of the most favorable targets for future direct imaging and astrometry missions surveying mature, terrestrial […]

Earth-like and super-Earth candidates from Bryson et al. (2021) are displayed in the effective temperature–instellation flux plane, as in Bryson et al. (2021). The conservative and optimistic habitable zones defined by Bryson et al. (2021) are shown in green. Marker sizes are proportional to the planetary radius. The candidates that were independently identified by our pipeline are shown in blue, the other with red. Out of five eliminated candidates three are in the conservative HZ, one is on the edge between the optimistic and conservative HZ and one in the optimistic HZ. Due to the overall small number of candidates in the habitable zone with radius < 1.8R⊕ this reduction could have a significant impact on η⊕ estimates. -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Exoplanet Transit Search At The Detection Limit: Detection And False Alarm Vetting Pipeline

by Keith CowingJanuary 25, 2026January 25, 2026

One of the primary mission goals of the Kepler space telescope was to detect Earth-like terrestrial planets in the habitable zone around Sun-like stars. These planets are at the detection […]

Terrestrial Planet

Coupling Dynamical Accretion And Chemical Differentiation: A Unified Framework For Earth-Mars Diversity

Ultraviolet-Driven Atmospheric Degeneracies Challenge Conventional Biosignature Frameworks for Terrestrial Planets with Ultracool M Dwarf Hosts: An Archean-Analog TRAPPIST-1 e Case Study

Oxidation Constraints On Terrestrial Planet Formation From A Ring

The HAges Catalog: Stellar Ages For High Priority HWO Target Stars

Exploring TRAPPIST-1 Climate States With An Energy Balance Model

Astrochemical Inheritance of Terrestrial Planets Water from Local Wet Silicates

Upper Atmosphere Dynamics and Drivers of Volatiles Loss from Terrestrial-Type (Exo)Planets

Gemini South Confirms Long-Suspected Link Between the Composition of Exoplanets and Their Host Stars

A Century of Radial Velocity and Astrometric Monitoring of 70 Oph AB: New PFS Data and Constraints on Planetary Companions

Exoplanet Transit Search At The Detection Limit: Detection And False Alarm Vetting Pipeline

A Search For Narrowband Technosignatures From LTT 3780 With The Allen Telescope Array And The Karl G. Jansky Very Large Array

Tricorder Tech: Identifying Proteins, Molecule By Molecule

First Completed Rocky Worlds Program Observations Open New Era in Exoplanet Studies

Pioneer 10/11 Telemetry Explanatory Almanac

Diverse Organic Molecules Discovered Surrounding A Newly Formed Star