Good News, Alien Seekers: E.T. Probably Doesn’t Need a Freaky-Big Moon Like Ours by Senior Astronomer Seth Shostak
January 26, 2012
The Moon is a ball of left-over debris from a cosmic collision that took place more than four billion years ago. A Mars-sized asteroid—one of the countless planetesimals that were frantically churning our solar system into existence—hit the infant Earth, bequeathing it a very large, natural satellite.
OK, that’s a bit of modestly engaging astrophysics. But some scientists think there’s a biological angle here. Namely, that elaborate terrestrial life might never have appeared if that asteroid had arrived a few hours earlier, and sailed silently by. Put another way, if every night were moonless, you wouldn’t be around to notice the lack of a moon.
But is that true? Did our cratered companion really make our existence possible?