For Earth Day on April 22, interesting facts including who invented it, why it's on that date, and how it turned into a global movement.

Add Yahoo as a preferred source to see more of our stories on Google. This year marks the 55th anniversary of Earth Day! Every year on April 22, people worldwide mobilize to address some of the most ...

Ah, Earth. We may not think about our planet on a day-to-day basis, but the world we live in is a pretty interesting place. The third rock from the Sun—and to this day, the only one with known ...