Theia, who's impact on Earth created moon, was its neighbour: Study
Celestial body Theia, which collided with young Earth and resulted in moon's formation, may have actually formed in inner solar system. A study published in Science journal suggests Theia was once Earth's neighbour. The study said Theia was a rocky planet with a metallic core, weighing about 5-10% of Earth's mass, and it likely formed closer to Sun than Earth.