Nasa satellites show battered Moon
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.