Over 4.5 billion years ago, a giant body smashed into Earth in a cosmic collision that birthed our planet's loyal companion, the moon. Now, new research indicates that this body, named Theia, may have actually formed in the inner solar system with Earth, meaning it was once our planet's neighbor.
Scientists already knew a lot about how this collision influenced Earth beyond the creation of the moon, including how it affected the shape, composition, and mass of our planet and how it shifted its orbit around the sun. However, the fact that Theia was completely obliterated in this collision means there are still many unanswered questions about the impactor itself. These include: What type of object was Theia? How big was it? What was it made of? And where in the solar system did Theia emerge from to smash into Earth?
