Rocky exoplanets are thought to be abundant in the Milky Way, however the existence and composition of their atmospheres are generally unknown. The existence of a stable atmosphere depends on several factors, including the total amount of radiation received (which is related to the spectral type of the host star), the surface gravity (related to mass and radius), and the orbital period.
In 2024, 55 Cancri Ae became the first terrestrial exoplanet to have its atmosphere detected with high confidence. Its atmosphere might have been re-generated by a magma ocean, and is composed of either carbon monoxide (CO) or carbon dioxide (CO2). Later studies found evidences of atmosphere for the sub-Earth planet L 98-59 b, the evaporating planet K2-22b, and the super-Earth planets TOI-561 b and HD 3167 b.
Table To be included in the following list, an exoplanet must: Be terrestrial or nearly terrestrial (density > 3.0 g/cm3 and radius < 2.0R⊕) Transit its host star from view of Earth Have been studied with transmission spectroscopy or secondary eclipse and have a published claim or inference of atmospheric detection, whether confirmed or not
Note that mass values prefixed with "~" have not been measured, but are estimated from the mass-radius relationship.
+ Row colors key Solar system planet for reference Solar system moon for reference Rocky exoplanet with confirmed atmosphere detection Rocky exoplanet with unconfirmed atmosphere detection Mini-Neptune planet for reference
Planet/MoonHostSpectral typeMass (M⊕)Radius (R⊕)Existence of atmosphereComposition of atmosphere (by volume)Atmospheric pressure at surface (atm)Period (days)Distance (ly)Refs/notes Earth(reported for reference) Sun G2V Confirmed 78.08% nitrogen, 20.95% oxygen, 0.93% argon, water vapour and other trace gases 1.0 Only planet confirmed to harbour life Venus(reported for reference) Sun G2V Confirmed 96.5% carbon dioxide, 3.5% nitrogen, sulfur dioxide and other trace gases 92 ~ Has disputed detection of possible extremophile life Mars(reported for reference) Sun G2V Confirmed 95.97% carbon dioxide, 1.93% argon, 1.89% nitrogen, oxygen and other trace gases 0.0063 ~ ; Mean Anomaly (deg) 19.412 = (Mean Longitude (deg) 355.45332) – (Longitude of perihelion (deg) 336.04084) Titan(reported for reference) Saturn – Confirmed (for the troposphere) 97% nitrogen, % methane, 0.1–0.2% hydrogen, organonitrogen haze 1.45 (sidereal) ~ Triton(reported for reference) Neptune – Confirmed nitrogen, methane and carbon monoxide traces 0.000014 (sidereal, retrograde) ~ LTT 1445 Ab LTT 1445 A M2.5V Unconfirmed Likely hydrogen cyanide Gliese 486 b (Su) Gliese 486 (Gar) M3.5V Unconfirmed Probably water vapour Unclear if the water vapour signal came from planet or host star Gliese 357 b Gliese 357 M2.5V Unconfirmed Likely carbon dioxide or abiotic oxygen Gliese 341 b Gliese 341 M1V ~ Unconfirmed Likely water vapour or other small molecules L 98-59 b L 98-59 M3V Confirmed Mostly sulfur dioxide L 98-59 c L 98-59 M3V Unconfirmed Likely hydrogen with traces of carbon dioxide and water vapour TRAPPIST-1b TRAPPIST-1 M8V Unconfirmed Likely carbon dioxide TRAPPIST-1c TRAPPIST-1 M8V Unconfirmed Likely mostly oxygen and carbon dioxide traces 0.1–10 (if an atmosphere exists) TRAPPIST-1d TRAPPIST-1 M8V Unconfirmed Probably carbon dioxide or clouds from water vapour 0.01 (approximate, if an atmosphere exists and is Mars-like) Located in the habitable zone TRAPPIST-1e TRAPPIST-1 M8V Unconfirmed Likely nitrogen with methane traces Located in the habitable zone LHS 475 b LHS 475 M3.5V ~ Unconfirmed Probably carbon dioxide 0.01 (approximate, if an atmosphere exists and is Mars-like without haze) 55 Cancri Ae (Janssen) 55 Cancri A (Copernicus) K0IV-V Confirmed Phosphorus monoxide, nitrogen and carbon dioxide or water vapour or phosphine, possibly with sodium and calcium 10 or higher GJ 1132 b GJ 1132 M4V Unconfirmed Likely oxygen or carbon dioxide or clouds from potassium chloride/ zinc sulfide GJ 1214 b (Enaiposha) GJ 1214 (Orkaria) M4.5V Confirmed Haze and carbon dioxide, possibly with helium Very high LHS 1140 b LHS 1140 M4.5V Unconfirmed (Upper atmosphere) Probably helium, (Lower atmosphere) Likely nitrogen and water vapour Located in the habitable zone LHS 1478 b LHS 1478 M3.5V Unconfirmed Likely pure carbon dioxide, carbon dioxide and water vapour or nitrogen and carbon dioxide 1–10 (if an atmosphere exists) The dark bare-rock scenario was considered unlikely TOI-260 b TOI-260 K8V Unconfirmed Probably ethylene, acetylene, gaseous carbon or ammonia The absorption features of these gases best match the 3.17 μm feature in the obtained spectra GJ 1252 b GJ 1252 M2.5V Unconfirmed Probably sodium, atomic oxygen and potassium 0.000001 or lower HD 97658 b HD 97658 K1V Confirmed Clouds and likely hydrogen, carbon monoxide and methane Very high TOI-732 c TOI-732 M3.5V Confirmed Methane, 1-pentene and other alkenes or diethyl sulfide Very high TOI-270 b TOI-270 M3V Unconfirmed Likely water vapour TOI-270 d TOI-270 M3V Confirmed Methane, carbon dioxide, water vapour, carbon disulfide, thioformaldehyde, possibly with sulfur dioxide and chloromethane or fluoromethane Very high L 168-9 b (Qingluan) L 168-9 (Danfeng) M1V Unconfirmed Likely carbon dioxide GJ 3473 b GJ 3473 M4V Unconfirmed Likely carbon dioxide or water vapour 1.2–6.5 or lower TOI-431 b TOI-431 K2V Unconfirmed - The dark bare-rock scenario was considered unlikely TOI-1685 b TOI-1685 M3V Unconfirmed Probably carbon dioxide or water vapour or sulfur dioxide HD 3167 b HD 3167 K0V Confirmed – K2-141b K2-141 K5V Unconfirmed Likely vapourized silicate-rock TOI-561 b TOI-561 G9V Confirmed Volatiles including water vapour and oxygen, likely has clouds from mineral vapour High TOI-1444 b TOI-1444 G8V Unconfirmed Probably reflective mineral clouds K2-22b K2-22 M0V < Confirmed Likely magnesium silicate dust and nitric oxide or carbon dioxide
See also Extraterrestrial atmosphere List of nearest terrestrial exoplanet candidates Lists of planets
Notes
References