Earth may have had a second, smaller moon that smacked into the larger one, which explains why one side of the moon is more rugged than the other.

Searching remote mountains in Borneo, scientists discover a group of brightly colored rainbow toads, a species last seen in 1924 and believed to be extinct. 

Elephants have social networks ranging from four to 16 “friends.” As with people, the smaller the circle, the stronger and more loyal the bond.

Good news: the wage gap between men and women in science is smaller than in other fields. Bad news: women still earn 12 percent less.

A Swedish man was arrested for unauthorized possession of nuclear materials after trying to split atoms in his kitchen. “It is just a hobby,” he wrote on his Web site.