
Two researchers hypothesize that an asteroid belt, just the right size and distance from its star, might be necessary for a star system to support a life-bearing planet.

Two researchers hypothesize that an asteroid belt, just the right size and distance from its star, might be necessary for a star system to support a life-bearing planet.

Plants shaped the surface of Earth, affecting the oceans and climate of our planet as they began to appear 470 million years ago.
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