Erik Asphaug and Martin Jutzi of the University of California have recently outlined a theroy that ancient Earth once orbited by two moons. Published in the journal Nature, the research stems from the fact that one side of our Moon has a starkly different landscape than the other side. Asphaug and Jutzi believe a collision from a second moon created mountainous piles of debris, which now exist in the form of jagged cliffs and rough terrain. Maria Zuber of MIT has supported this notion by pointing out this explains the existence of mountains on the moon; despite the fact the moon has no plate tectonics nor volcanic activity.
Moon2 would have probably orbited the Earth way back when the planet itself was still in formative stages, meaning there was no life present here to observe the two moons. But if there had been, we bet there would have been way too many werewolves to deal with. (Werewolves killed the dinosaurs?)
Check out the news story via NPR. And check out what life would be like if we had two moons today in this excerpt from What If the Earth Had Two Moons?
Stubby the Rocket is the voice and mascot of Tor.com. Stubby took care of the second moon a long time ago.