An Argument for the Cometary Origin of the Biosphere

摘要

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. Those missing years hold the key to everything we hold dear on the surface of our planet. Remarkably, we are still not sure exactly what took place during that time.