Earth may have once looked a little more like Mars: a planet with two moons. It's
not the first time
the theory has been trotted out by Erik Asphaug, but it's getting new life thanks to an upcoming conference about our natural satellite. The University of California at Santa Cruz professor will share the theory at the September conference, and the
has a preview. Asphaug says the second moon would have been much tinier—about 1/30th the size of our moon. But after orbiting Earth for a few million years, it would have had quite the impact, literally, on its larger twin.
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