Scientists have proposed a shocking new theory for the origin of the moon, and their calculations suggest Earth once had a secret world hiding right next door. Astronomers believe that the moon was ...

Over 4.6 billion years ago, Earth took shape from a spinning cloud of dust and gas surrounding the young sun. Tiny particles within this cloud collided and clumped together, driven by gravity and ...

New research suggests that Theia, the object whose collision with Earth is theorized to have caused the formation of the moon, came from closer to the sun. Artist’s impression of the collision between ...

Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. A small space rock ...