Where did the moon come from? What is it made of? And what events created the distinctive pattern of light and dark on its surface? To find out, we have sent satellites out to crash onto its surface, astronauts to comb its craters and hillsides and collect rocks, and high-tech spacecraft to map its nooks and crannies.
A half-century of study has brought us closer to the answers. Many scientists now believe that the moon was born in a monumental collision between Earth and a Mars-sized body early in the history of the solar system, some 4.5 billion years ago.