According to a new theory, there were two giant impacts in a row, separated by about one million years, involving a Mars-sized 'Theia' and proto-Earth. In this image, the proposed hit-and-run ...

The heavy core of Theia sank deep into Earth, enlarging our planet's core. The two bodies' mantles mixed and thus bulked up our planet. And the crusts were scattered far into space. What happened ...

These structures are theorized to contain remnants of Theia's materials ... the stars ‘Snowball Earth’: How volcanoes saved our planet from its deepest freeze in history ...

The leading explanation for all of these mysteries is known as the giant impact hypothesis. According to this story, when the solar system was just getting started, a Mars-size protoplanet named Theia ...