exo-Venus Archives - Astrobiology

The same gentle wind that would create small ripples on a lake in Earth (right) would make large waves on Saturn’s largest moon Titan (left). In these renderings, the marker is measured in meters. Credit Courtesy of Taylor Perron, Una Schneck, et al

Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Icy Worlds, Mars, Press Release, Titan, Water/Hycean Worlds & Oceanography

Waves Hit Different On Other Planets

by Keith CowingApril 20, 2026April 20, 2026

On a calm day, a light breeze might barely ripple the surface of a lake on Earth. But on Saturn’s largest moon Titan, a similar mild wind would kick up […]

Phase-folded RVs from the best-fit informed RV model with GPs removed. Binned data shown by the large, purple points (10 bins). Phasefolded on the period of the planet (12.761421 d). -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report, Venus

The Mass Of The Exo-Venus Gliese 12 b, As Revealed By HARPS-N, ESPRESSO, And CARMENES

by Keith CowingJune 27, 2025September 18, 2025

Small temperate planets are prime targets for exoplanet studies due to their possible similarities with the rocky planets in the Solar System.

Surface temperature (straddling 0◦C), total cloud cover (%), net outgoing thermal radiation (W m−2 ), and cloud water content (kg m−2 ) for four of the simulations listed in Table 1. Simulations are displayed from dry (Sim 01: Arid-Venus), semidry 10 m GEL (Sim 02: 10 m-Venus), Earth-like 310 m GEL (Sim 03: 310 m-Venus) and an aquaplanet (Sim 06). Sims 01–03 are 1 bar N2 dominated with 400ppmv CO2. Sim 06 is N2-dominated, but the only greenhouse gas is H2O following Wolf (2017). Cloud coverage is fairly low in Sims 01–02 as expected given limited surface reservoirs and cloud water content (rightmost column), and is much higher for Sims 03 and 06. -- astro-ph.EP

Astrogeology, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Press Release, TRAPPIST-1, Venus

TRAPPIST-1 d: Exo-Venus, Exo-Earth or Exo-Dead?

by Keith CowingFebruary 10, 2025February 10, 2025

TRAPPIST-1 d is generally assumed to be at the boundary between a Venus-like world and an Earth-like world, although recently published works on TRAPPIST-1 b and c raise concerns that […]

Gliese 12 b’s estimated size may be as large as Earth or slightly smaller — comparable to Venus in our solar system. This artist’s concept compares Earth with different possible Gliese 12 b interpretations, from one with no atmosphere to one with a thick Venus-like one. CREDIT NASA/JPL-Caltech/R. Hurt (Caltech-IPAC)

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Press Release, Venus

Gliese 12 b, A Potentially Habitable Exo-Venus With Earth-like Temperature

by Keith CowingMay 23, 2024May 23, 2024

Astronomers have made the rare and tantalising discovery of an Earth-like exoplanet 40 light-years away that may be just a little warmer than our own world.

Mass - radius relations of puffy Venuses. a: M-R relations compared to observed exoplanets. The grey line is the M-R for terrestrial planets with an Earth-like core mass fraction of 0.325 (Plotnykov & Valencia 2020). Colored solid lines are puffy Venus radii assuming different Teq, with the fiducial, OC-like volatile C and H abundances. The orange dashed line is the M-R for Teq = 2000 K planets with a convective deep atmosphere to the MO surface, instead of a deep radiative zone. The shaded region is the range of M-R space an air-less rocky world can occupy for all possible Fe/Si ∈ [0, 1]. Planets less dense than this region require a volatile component. Measured exoplanet samples are from the NASA Exoplanet Archive (2023), and only contain those with relative errors below 30%. The nine planets highlighted with black circles are our preferred puffy Venus candidates. In rising mass order, they are GJ 1252 b, TOI-500 b, TOI-561 b, Kepler-10 b, Kepler-36 b, HD 219134 b, HD 3167 b, WASP-47 e, and 55 Cnc e. TOI-561 b’s radius is from Patel et al. (2023); its mass is from Brinkman et al. (2023) b: M-R of puffy Venuses with a range of chondritic C abundances, more opaque lines correspond to less C. They are color-coded by temperature - Teq = 1000 K (blue) and 2000 K (orange). The dashed orange line is for wet CI composition, while the solid line with the same color is for dry CI composition. The dotted portion of dry CI, 1000 K line are atmospheres that should experience graphite precipitation; see text. c: M-R of models assuming different chemical scenarios - I (solid), local chemical equilibrium throughout the atmosphere, II (dash-dot), chemical equilibrium at the MO surface, and a CO2 + H2O atmosphere (dotted). Fiducial OC C and H abundances are used. Same color-coding as b. The solid 1000 K and 2000 K lines in a, the 2 OC lines in b, and the 2 Scenario I lines in c are the same. -- astro-ph.EP

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Lava / magma ocean / Volcanic Worlds, Status Report, Venus

Puffy Venuses: the Mass-Radius Impact of Carbon-Rich Atmospheres on Lava Worlds

by Keith CowingMay 16, 2024May 16, 2024

The recent advancements in exoplanet observations enable the potential detection of exo-Venuses, rocky planets with carbon-rich atmospheres. How extended these atmospheres can be, given high carbon abundances, has not been […]