Extraterrestrial life

:This article is about the scientific study of extraterrestrial life; for treatment in popular culture, see Extraterrestrial life in popular culture.

Extraterrestrial life in the Solar System

Many bodies in the Solar System have been suggested as being likely to contain life. The most commonly suggested ones are listed below; of these, four of the five are moons thought to have large bodies of underground liquid, and life may have evolved there in a similar fashion to deep sea vents.

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• Mars - The best known of the other planets and moons in the Solar system. There was liquid water on Mars in the past and there may be liquid water beneath the surface. Recently, methane was found in the athmosphere of Mars.
• Titan - Only known moon with a significant atmosphere. Recently visited by the Huygens probe. Latest discoveries indicate that there is no global or widespread ocean, but small and/or seasonal liquid hydrocarbon lakes are still possible.
• Europa - probably has a salt ocean under a thick ice crust.
• Ganymede - Jupiter's largest moon, and indeed the largest moon in the entire solar system
• Enceladus - May have liquid water beneath its surface. http://www.newscientist.com/article.ns?id=dn7159

Numerous other bodies have been suggested as potentially life-bearing. For example, atmospheric life has been hypothesised on Venus and the gas giants. Fred Hoyle also proposed that microbial life might exist on comets. Some Earth microbes also managed to survive on a lunar probe for some years. It is considered highly unlikely that complex multicellular organisms exist in any of these places.

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