Nasa satellites show battered Moon
5 December 2012 Last updated at 21:56 GMT
The scale of the battering the Moon received early in its history has been revealed in remarkable new data from two Nasa satellites.
Ebb and Flow - together known as the Grail mission - have mapped the subtle variations in gravity across the surface of the lunar body.
They show the Moon's crust to be a mass of pulverised rock - the remains of countless impacts.
Prof Maria Zuber told our correspondent Jonathan Amos how Ebb and Flow measured lunar gravity.