Fifty million years after the birth of our solar system, the moon may have formed from the debris of a collision between Earth and a Mars-sized body named Theia. For this to be true, Theia would have to have hit earth at a relatively low speed. Richard Gott and Edward Belbruno of Princeton University say that this could only have happened if Theia had originated in a Lagrange point. The discovery of the KOI-730 planets shows that it is possible.