List of terrestrial exoplanet candidates for atmosphere detection

The rocky exoplanets are thought to be abundant in the Milky Way, however their existence of atmosphere and their atmospheric composition are generally unknown.^[1] The existence of a stable atmosphere depends on several factors including total amount of radiation receive (which is related to the spectral type of host star), the surface gravity (related to mass and radius) and the orbital period.^[2]

As of 2024, 55 Cancri e is the first and the only terrestrial exoplanet with verified atmospheric detection. Its atmosphere might have been re-generated by the magma ocean and is composed of either carbon monoxide (CO) or carbon dioxide (CO₂).^[3]

Artist's impression of L 98-59 b as a rocky planet with an atmosphere

Table

To be included in the following list, an exoplanet must:

• Be terrestrial or nearly terrestrial (density > 3.0 g/cm³ and radius < 2.5R_⊕)
• Transit the host star from the Earth's view
• Have been studied with the transmission spectroscopy or secondary eclipse and have published claim(s) of atmospheric molecule 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

Exoplanet with confirmed atmosphere detection

Exoplanet with unconfirmed atmosphere detection

Planet/Moon	Host	Spectral type	Mass (M⊕)	Radius (R⊕)	Existence of atmosphere	Composition of atmosphere (by volume)	Period (days)	Distance (ly)	Refs/notes
Earth (reported for reference)	Sun	G2V	1.00	1.00	Confirmed	78.08% nitrogen, 20.95% oxygen, 0.93% argon, water vapour and other trace gases	365.25	0	[4]
Venus (reported for reference)	Sun	G2V	0.815	0.950	Confirmed	96.5% carbon dioxide, 3.5% nitrogen, sulfur dioxide and other trace gases	244.26	~0	[5]
Mars (reported for reference)	Sun	G2V	0.107	0.533	Confirmed	95.97% carbon dioxide, 1.93% argon, 1.89% nitrogen, oxygen and other trace gases	686.98	~0	[6]
Titan (reported for reference)	Saturn	–	0.0225	0.404	Confirmed	(for the troposphere) 97% nitrogen, 2.7±0.1% methane, 0.1–0.2% hydrogen	15.945 (sidereal)	~0	[7]
Triton (reported for reference)	Neptune	–	0.0036	0.212	Confirmed	nitrogen, methane and carbon monoxide traces	5.877 (sidereal, retrograde)	~0	[8]
LTT 1445 Ab	LTT 1445 A	M2.5V	2.73	1.34	Unconfirmed	Probably hydrogen cyanide	5.36	22.4	[9]
Gliese 486 b	Gliese 486	M3.5V	2.77	1.29	Unconfirmed	Probably water vapour	1.47	26.3	[10]
Gliese 357 b	Gliese 357	M2.5V	1.84	1.22	Unconfirmed	-	3.93	30.8	[11]
Gliese 341 b	Gliese 341	M1V	0.73	0.89	Unconfirmed	Likely water vapour or other small molecules	7.58	34.1	[12]
L 98-59 b	L 98-59	M3V	0.47	0.85	Confirmed	Likely sulfur dioxide	2.25	34.6	[13]
L 98-59 c	L 98-59	M3V	2.22	1.38	Unconfirmed	Likely carbon dioxide and water vapour	3.69	34.6	[14]
TRAPPIST-1b	TRAPPIST-1	M8V	1.37	1.12	Unconfirmed	Likely carbon dioxide	1.51	40.6	[15]
TRAPPIST-1c	TRAPPIST-1	M8V	1.31	1.10	Unconfirmed	Likely 99% oxygen + 1% carbon dioxide	2.42	40.6	[16]
TRAPPIST-1e	TRAPPIST-1	M8V	0.69	0.92	Unconfirmed	Likely nitrogen with methane traces	6.10	40.6	Located in the habitable zone[17]
LHS 475 b	LHS 475	M3.5V	~0.91	0.99	Unconfirmed	Probably carbon dioxide	2.03	40.7	[18]
55 Cancri e	55 Cancri A	K0IV-V	7.99	1.87	Confirmed	Carbon monoxide or carbon dioxide, possibly with sodium and calcium	0.736	41.0	[3][19]
LHS 1140 b	LHS 1140	M4.5V	5.60	1.73	Unconfirmed	Likely nitrogen and water vapour	24.74	48.8	Located in the habitable zone[20][21]
LHS 1478 b	LHS 1478	M3.5V	2.33	1.20	Unconfirmed	Likely carbon dioxide and water vapour/ nitrogen	1.95	59.4	[22][16]
HD 97658 b	HD 97658	K1V	7.81	2.25	Unconfirmed	Likely hydrogen, carbon monoxide and methane	9.49	70.3	[23]
TOI-732 c	TOI-732	M3.5V	8.04	2.39	Unconfirmed	Likely methane	12.25	71.8	[24]
TOI-270 b	TOI-270	M3V	1.48	1.30	Unconfirmed	Likely water vapour	3.36	73.3	[25]
L 168-9 b	L 168-9	M1V	4.07	1.63	Unconfirmed	Likely carbon dioxide	1.40	82.1	[26]
TOI-431 b	TOI-431	K2V	3.07	1.24	Unconfirmed	-	0.490	106	[27]
TOI-1430 b	TOI-1430	K2V	4.16	1.92	Confirmed	Neutral helium (He I)	7.43	134	[28]
K2-141b	K2-141	K5V	5.08	1.51	Unconfirmed	Likely vapourized silicate-rock	0.280	202	[29]
K2-22b	K2-22	M0V	0.02	<0.71	Confirmed	Likely magnesium silicate dust and NO/CO2	0.381	801	[30]

See also

• Extraterrestrial atmosphere
• List of nearest terrestrial exoplanet candidates
• Lists of planets