The Moon may have been formed not from one big cosmic smash, as the leading theory holds, but from multiple smaller collisions.

Billions of years ago in the early Solar System, space debris would have collided with the young Earth. Using computer simulations, a team led by Raluca Rufu of the Weizmann Institute of Science in Rehovot, Israel, found that multiple small impacts could have formed many moonlets around Earth. Those would then have coalesced to create the Moon.

The scenario could explain why Earth and the Moon have similar chemical compositions. Researchers think that a Moon created by a single large impact would have contained material both from the impactor and from Earth.

Nature Geosci. http://dx.doi.org/10.1038/ngeo2866 (2017)