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Phoenix666 [soylentnews.org] writes:

All life (as we know it) depends on carbon. But most models of Earth's formation can't explain how the crust has enough carbon to support life. So where did it all come from?

A colossal smashup [csmonitor.com] with a Mercury-like protoplanet some 4.4 billion years ago, suggest researchers from Rice University and Woods Hole Oceanographic Institution in a new study [nature.com] published in the journal Nature Geoscience.

Most scientists agree that about 4.5 billion years ago, Earth was covered with hot magma, and as it cooled, most of the heavier metals near the surface sank deep into the planet. Iron alloys bonded with carbon and sulfur, pulling both into the Earth's core, and any remaining carbon would have vaporized into space from the extreme heat, argue the scientists. The only way to keep carbon and sulfur near the surface is to bring some from a planet that formed differently, they say.

A different story reported last week that scientists have identified fossilized stromatolites [cnn.com] that date to 3.7 billion years ago, or 700 million years after the worst day ever for the young Earth.

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