Chapter category: Evolution

Comets and Astrobiology

This chapter appears in the following book:

Prebiotic Evolution and Astrobiology

Edited by: J. Tze-Fei Wong and Antonio Lazcano
ISBN: 978-1-58706-330-5
» Get more information about this book at landesbioscience.com «

Chapter authors:
Hervé Cottin and Didier Despois

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For a very long time, comets were regarded as bad omens, linked to superstitions, wars, deaths, diseases, etc… But nothing was really known about these wandering objects, suddenly appearing and disappearing in the sky, without prior notice. They were considered by Aristotle as an atmospheric phenomenon and not until the 17th century were they actually seen as astrophysical bodies by western scientists. In a milestone paper, F. Whipple describes in 1950 comets as “dirty snowballs”, a mixture of ices (dominated by water) and minerals. This model has long since evolved: more is known about the nature of the nucleus from data collected with Earth‑based observations, in situ investigations, sample returns and laboratory work. To date, our current knowledge gives comets a privileged location in astrobiology: they are at the crossroads of the origins. Origin of the Solar System, since they have sampled the matter of the Solar Nebula at the place of their accretion, but also, possibly, the origin of life on Earth since comets are rich in water and carbon, two essential constituents of terrestrial life. Therefore part of Earth’s water and carbon might be of cometary origin.

Hervé Cottin
LISA, Universités Paris 12 et Paris 7, CNRS

Didier Despois
Observatoire Aquitain des Sciences de l'Univers

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Chapter category: Evolution

Comets and Astrobiology

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