Leftovers

Leftovers! And it's not just that cold pizza and warm beer you're having for breakfast. Turns out our Solar System uses them, too.

Mars and Mercury Formed From Planetary Scraps

Mars and Mercury were formed from the scraps of Earth and Venus, according to a radical new theory of rocky planet formation.

If the rocky planets formed from a homogenous debris disk, they should all be roughly the same size and orbit the sun in similar circular orbits, Youdin explained.

In reality, however, Venus and Earth are much more massive than Mercury and Mars, and the orbits of the latter two planets are more elliptical, or eccentric, than expected.

"The traditional explanation is that this is luck—or more scientifically, 'chaos'—with Jupiter's proximity to Mars perhaps playing a role," Youdin said, referring to the large gravitational pull of a planet as big as Jupiter.

So Mars is the perfect candidate for a home away from home.