
Sometime in our Solar System’s past, a 500-mile-wide ball of rock called 2002 MS4 was peacefully drifting through the Kuiper Belt, minding its own business, when something smashed into its northern hemisphere.

Sometime in our Solar System’s past, a 500-mile-wide ball of rock called 2002 MS4 was peacefully drifting through the Kuiper Belt, minding its own business, when something smashed into its northern hemisphere.