Boletín de la Sociedad Geológica Mexicana

Volumen 67, núm. 3, 2015, p. 377-385

Methane in the Solar System

Andrés Guzmán-Marmolejo1, Antígona Segura2,*

1 Posgrado en Ciencias de la Tierra, Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán. C.P. 04510, D.F., México.
2 Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito exterior C.U. Apartado Postal 70-543. Coyoacán, C. P. 04510, D.F., México.

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Abstract

This paper reviews the distribution of methane (CH4) in our Solar System, as well as its sources and sinks in the atmospheres of the main Solar System bodies. Methane is widely distributed in the Solar System. In general, the inner planets are methane-poor, being Earth a unique exception, whereas the outer planets have CH4-rich atmospheres. In general, the atmospheric chemistry of this compound is dominated by the solar radiation although in O2-rich atmospheres this compound participates in a reaction system that removes atmospheric CH4. In our planet most of the atmospheric CH4 is produced by lifeforms, reason why scientists have proposed that the simultaneous detection of methane signal along with oxygen (O2) or ozone (O3) signals in the atmospheric spectra of planets may be good evidence of life. Therefore, the study of this gas at planetary level is important for understanding the chemical reactions that control its abundance on the exoplanetary atmospheres and to classify possible inhabited planets.

Keywords: methane, biosignatures, Solar System.