Every Ghost World In Our Solar System Explained In 15 Minutes

Theia It was the ghost world with the strongest claim to having existed, because its remains are visible in the sky every night. It was a protoplanet, a world roughly the size of Mars, that formed in the early solar system alongside the Earth around 4.5 billion years ago. It was named after the Greek Titaness who was the mother of Selene, the goddess of the Moon, and the name turned out to be fitting. One leading idea holds that it grew at a gravitationally stable point along Earth's own orbit, a position that could hold a small world in place for a time but not forever. According to the giant impact hypothesis, it eventually drifted loose and struck the young Earth in a collision so violent that it melted both bodies and threw an enormous volume of vaporized rock into orbit. That debris settled into a ring and slowly gathered itself into a single object. The Moon.