Moon Likely Formed From Collision Between Early Earth and Theia

Earth’s Moon is unusually large compared with the planet it orbits, and the leading explanation begins with catastrophe

Earth’s unusually large moon likely formed from a violent collision with a Mars-sized planet named Theia about 4.5 billion years ago. New geochemical analyses of Apollo lunar samples and terrestrial rocks indicate that Theia and early Earth originated from a similar region of the inner solar system. For decades, astronomers debated how Earth acquired a … Read more