Recently Added Non-Detections: HCCSH, H2CCS, lactaldehyde,
succinonitrile, CH3(13CO)CH3

Recently Added Isotopologues: 13CH3C(O)CH3

Molecules can exist in a wide range of astrophysical environments, from the extremely cold regions between stars to the atmospheres of stars themselves.

To date, nearly 200 molecular species have been tentatively or definitively identified in interstellar or circumstellar clouds, while about 50 have been identified in studies of comets in our solar system. Numerous isotopologues of interstellar and circumstellar molecules have also been observed.

Some detections reported on these pages may be controversial, but all are taken from the peer-reviewed astronomical literature. A questionable identification may be removed at a later date if circumstances warrant.

Jacque Crovisier has amassed a comprehensive compilation of species observed to date in the interstellar medium, in comets, or in non-terrestrial planetary atmospheres, plus additional ones which may prove to be found.

UPDATED 12/2018: See the article by Brett McGuire in ApJS, 2018 Census of Interstellar, Circumstellar, Extragalactic, Protoplanetary Disk, and Exoplanetary Molecules. In addition to lists of observed molecules, the article provides a good overview about astronomical observation and the spectroscopy associated with detecting molecules.

Interstellar & Circumstellar Molecules
  MgC3N, MgC4H
Cometary Molecules
Molecules on Planetoids
Protoplanetary Disk Molecules
Planetary Molecules
CH2CCH2 on Titan
Exoplanetary Molecules
Molecules in Brown Dwarfs and Stellar Atmospheres

Maintained by DE Woon
Updated 1 November 2019