Collision with Second Moon Caused Lunar Highlands

The dark side of the moon likely bears the scars of a massive moon-on-moon collision millions and millions of years ago.

The rugged, rocky, and little understood far side of the moon is so drastically different from the side facing us likely because it bears the remains of a second moon that once orbited Earth, according to a study published in the journal Nature. The theory that Earth had two moons has gained credence steadily over the past decade, but just where that second moon went has never properly been explained. The article's authors set up simulations to determine what would happen if the two moons collided, and found that the second, smaller moon wouldn't have necessarily left a crater, but instead a great amount of debris to create the mountains that populate the far side's highlands. Further, the scientists posit that the impact would have destabilized the moon's magma ocean, sending it to the close side where the remains of it can be seen today. Which is all a pretty fancy way of saying MOONS COLLIDED TO MAKE ONE MEGA MOON.