Moon
PHOTO: Flickr/PenguinBush

This October, the journal Science published a new theory about our moon’s origin that would explain why planet Earth and the moon have many things in common. Two Harvard scientists believe that Earth’s moon is actually a piece of our planet that flew off after a giant collision around five billion years ago with something the size of Mars. At the time of the collision, Earth was rotating so fast that an entire day passed by in under three hours.