As March Madness heats up, the folks at NASA's Earth Observatory are running their own tournament to choose the best images of Earth from space.
Until April 4, readers can vote in Tournament Earth for the most compelling, shocking or awe-inspiring images of our planet. Current contenders capture red-hot lava spewing from Mt. Etna in Italy, the breaking of an iceberg of Antarctica's Pine Island Glaciers, and the trails left by ships gliding across the ocean. Like the traditional March Madness competition, at the end of voting each week, only half of the photos survive to the next round, until only one is left and crowned champion.