In hopes of seeing whether there's water or ice on the moon, NASA is crashing two spacecraft onto the moon's surface. The AP explains, "The crashing spaceship was launched in June along with an orbiter that's now mapping the lunar surface. LCROSS -- short for Lunar Crater Observation and Sensing Satellite and pronounced L-Cross -- is on a collision course with the moon, attached to an empty 2.2-ton rocket that helped get the probe off the ground."

NASA says that the rocket—the Atlas V's Centaur—is expected to make impact with the moon around 7:30 a.m. (creating a 6.2 mile dust plume), and then four minutes later, the LCROSS "will fly through the debris plume, collecting and relaying data back to Earth before impacting the lunar surface and creating a second debris plume." (Here's a good graphic.) The LCROSS project manager Dan Andrews said, "'This is going to be pretty cool. We'll be going right down into it. Seeing the moon come up at you is pretty spectacular."

NASA will stream coverage starting at 6:15 a.m. at NASA TV. More fun stats from the AP: The spacecraft will hit the moon at 5,600 mph or "more than seven times the speed of sound" and "the explosion will have the force of 1.5 tons of TNT and throw 772,000 pounds of lunar dirt out of the crater." (FYI—the moon experiences crashes like this a few times a month from regular ol' space rocks.)