An Argument for the Cometary Origin of the Biosphere

By Armand Delsemme

The evidence suggests that a rain of comets brought the Earth its water, its organic molecules and its atmosphere—key ingredients for life's beginnings

Astronomy Physics Geology

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September-October 2001

Volume 89, Number 5
Page 432

DOI: 10.1511/2001.34.432

The first 600 million years of our planet's history have been erased from its surface. Between the time it was formed about 4.6 billion years ago and the formation of the oldest known sedimentary rocks, which are about 4 billion years old, the Earth changed from a hot, dry little rock to a world with an ocean and an atmosphere—a planet that was primed for the origin of life.

William K. Hartmann

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