Pluto is classified as a Kuiper Belt Object and therefore listed on the Planetoids page.
↓ Satellite Atmospheres ↓

MOST RECENT DETECTION(S) OR NON-DETECTION(S)
JWST Reveals the Kuiper Belt-like Compositions of the Uranian Rings and Small Moons Belyakov+ ApJL1010, L18 (2026)
PHOSPHINE ON VENUS PAGE
Click here.

     
AsH3
arsine 		ASTROMOLECULE OF THE MONTH FOR FEB 2020
CH3
methyl radical 		ASTROMOLECULE OF THE MONTH FOR JAN 2015
CH4
methane 		ASTROMOLECULE OF THE MONTH FOR AUG 2004
C2H2
acetylene 		ASTROMOLECULE OF THE MONTH FOR JUN 2013
C2H4
ethylene 		ASTROMOLECULE OF THE MONTH FOR JAN 2007
C2H6
ethane
C3H8
propane 		ASTROMOLECULE OF THE MONTH FOR MAR 2004
C3H6
propene
C3H4
propyne
C3H4
propadiene
C4H2
diacetylene 		ASTROMOLECULE OF THE MONTH FOR JUN 2004
C6H6
benzene
C9H12
trimethylbenzene
C10H14
tetramethylbenzene
C10H8
naphthalene
C10H10
dihydronaphthalene
C11H10
methylnaphthalene
C8H8O2
methyl benzoate
CO
carbon monoxide 		ASTROMOLECULE OF THE MONTH FOR JUN 2003
CO+
ionized CO
CO2
carbon dioxide 		ASTROMOLECULE OF THE MONTH FOR MAR 2011
CS
carbon monosulfide 		ASTROMOLECULE OF THE MONTH FOR SEP 2006
CS2
carbon disulfide
ClO
chlorine monoxide
GeH4
germane
H2
hydrogen 		ASTROMOLECULE OF THE MONTH FOR OCT 2013
H2+
dihydrogen cation
H3+
protonated hydrogen 		ASTROMOLECULE OF THE MONTH FOR JUL 2009
HCN
hydrogen cyanide 		ASTROMOLECULE OF THE MONTH FOR SEP 2010
HCl 
hydrogen chloride 		ASTROMOLECULE OF THE MONTH FOR NOV 2011
HF
hydrogen fluoride 		ASTROMOLECULE OF THE MONTH FOR APR 2004
H2O
water
H2S
hydrogen sulfide 		ASTROMOLECULE OF THE MONTH FOR NOV 2009
H2S+
ionized H2S
H2SO4
sulfuric acid 		ASTROMOLECULE OF THE MONTH FOR DEC 2017
N2
nitrogen 		ASTROMOLECULE OF THE MONTH FOR AUG 2008
NH3
ammonia 		ASTROMOLECULE OF THE MONTH FOR FEB 2010
NO
nitric oxide
N2O
nitrous oxide 		ASTROMOLECULE OF THE MONTH FOR JUN 2014
O2
oxygen
O3
ozone
OCS
carbonyl suifide 		ASTROMOLECULE OF THE MONTH FOR SEP 2005
PH3
phosphine 		ASTROMOLECULE OF THE MONTH FOR MAR 2007
S3
trisulur
SO
sulfur monoxide 		ASTROMOLECULE OF THE MONTH FOR NOV 2012
SO2
sulfur dioxide 		ASTROMOLECULE OF THE MONTH FOR AUG 2003
SO3
sulfur trioxide
OSSO
disulfur dioxide
C8H6S
benzothiophene
Non-detections indicated with dashed lines.




SATELLITES

For the most part, the moons of the solar system have very tenuous atmospheres (known as exospheres) that consist of volatile molecules created when surface materials are subject to irradiation by the solar wind or by ions accelerated by the magnetic field of the planet to which the satellite belongs. The one moon with a dense atmosphere is Titan, where the pressure at the surface is about half again as much as the pressure on Earth at sea level. Io has volcanoes that erupt gases into its atmosphere. Enceladus has cryovolcanoes. NOTE: Cited species are in the gas phase unless indicated otherwise.

EARTH'S MOON (LUNA)
Luna CH4 (1975)    CO2 (1975)    NH3 (1975)    H2O (2021)
MOONS OF JUPITER
Callisto H2O(s) (1973)    CO2 (1992)    O2 (2005)    H2 (2022)
H2O (nd)(2022)    O3 (2024)
Europa H2O(ice) (1973)    O2 (1995)    NaCl (2019)    H2O (2020)
NH3(ice) (2025)
Ganymede H2O(s) (1973)    O2(s?) (1995)    O3(s?) (1996)    O2 (1998)
H2O2(s) (2023)    CO2(s) (2024)    salts(s) (2024)
NaCl(s) (2024)    NH4Cl(s) (2024)
carbonates(s) (2024)    aliphatics(s) (2024)
CO2(g) (2024)
Io SO2 (1990)    SO (1996)    S2 (2000)    NaCl (2003)
MOONS OF SATURN
Dione O3 (1997)    CO2 (2016)    O2 (2016)
Enceladus H2O(s) (1977)    H2O (2006)    CO2 (2006)    CH4 (2006)    NH3 (2006)
   H2O2(s) (2007)    H2O (2008)    H2 (2017)    H2O2(s,disp) (2009)
CH3OH(s) (2021)    HCN (2024)    C2H2 (2024)    C3H6 (2024)
C2H6 (2024)
Rhea O3 (1997)    CO2 (2016)    O2 (2016)    N2H4 (2021)
Titan CH4 (1944)    C2H2 (1981)    C2H4 (1981)    C2H6 (1981)    HCN (1981)
N2 (1981)    CH3CCH (1981)    C4H2 (1981)    HC3N (1981)    C2N2 (1981)
H2 (1981)    CO (1983)    H2O (1998)    C6H6 (2003)    C3H8 (2003)
HNC (2011)    C2H5CN (2015)    C4N2(nd) (2015)    C2H3CN (2017)
H2CCCH2 (2019)    c-C3H2 (2020)    CH3C3N (2020)    CH4 (opt)(2025)
HC5N (nd)(2025)    C6H2 (nd)(2025)    C4N2 (nd)(2025)
C3 (2026)
MOONS OF URANUS
Ariel H2O(s) (1981)
Juliet H2O(s), CO2(s) (2026)
Oberon H2O(s) (1980)
Perdita H2O(s), CO2(s) (2026)
Portia H2O(s), CO2(s) (2026)
Puck H2O(s), CO2(s) (2026)
Titania H2O(s) (1980)
Umbriel H2O(s) (1980)
MOONS OF NEPTUNE
Triton CH4 (1979)    N2 (1989)    CO (2010)
pink=tentative detection


Acknowledgments

Listings of molecular species found in the atmospheres of the planets are taken in part from Photochemistry of Planetary Atmospheres by Y. L. Yung & W. B. DeMore (Oxford University Press, New York), 1999.

Images of the planets are adapted from Views of the Solar System by Calvin J. Hamilton. Most of the satellite images are from the Solar Yearbook.



Maintained by DE Woon
Updated 19 October 2026