AN EXTRA planet in the Solar System could have been the culprit in a massive
series of impacts that battered the Moon nearly 4 billion years ago.
Huge craters were formed on the lunar surface when objects up to 100
kilometres across crashed into it during a 100-million-year period called the
Late Heavy Bombardment. This seems to have come after a long spell of relative
calm in the inner Solar System. So astronomers have been wondering where these
objects were in the 600 million years between the formation of the Solar System
and the moment they began to hit.
John…
