Scientists rethink old ideas about the moon
As scientific mysteries go, the moon has long seemed a closed case. Astronauts have bounded across it and returned with vials of rocky soil. Machines outfitted with sophisticated instruments have circled, and crash-landed on it. Been there, done that. But a resurgence of interest in lunar science, led in part by local scientists, is raising new questions about our closest neighbor -- how much water is up there, for example, and did the Earth once have two moons?