Even the tiniest visual anomaly on Mars sends Earthlings reeling in imaginative speculation. In the past few years, cameras we've sent to Mars have turned up "Martians" of every variety: iguanas, rats, turtles, squirrels, Yetis, humanoid faces, and an entire alien base camp and mothership.

Hollywood is in the midst of a science-fiction boom, yet few of its sci-fi movies are based on real science. That's a shame, because the scientific discoveries emerging from NASA these days are as exciting as any Hollywood blockbuster.