Earth could have been a scorching, Venus-like world save for this one thing

Earth formed 4.5 billion years ago, but it looked nothing like it did today.

Instead, it was a boiling hot, inhospitable world, pelted with incoming space rocks that rained down on the planet.

At some point in this early chaos, a Mars-sized rock crashed into Earth. The impact may have created the Moon, but it also transformed Earth's entire surface into a molten magma ocean.