Lunar impacts created seas of molten rock

Melting on a massive scale

An impact event that formed the Orientale basin created a sea of molten rock 220 miles across and six miles deep. More recent lunar melts may help explain some puzzling questions and lead to some reinterpretations of lunar data including Apollo “moon rocks.” Credit: NASA

A new analysis of data from NASA’s Lunar Orbiter Laser Altimeter (LOLA) shows that molten rock may have been present on the Moon more recently and for longer periods than previously thought. Differentiation — a settling out of rock layers as liquid rock cools — would require thousands of years and a fluid rock sea at least six miles deep.