A discarded upper stage of a SpaceX Falcon 9 rocket is set to slam into the moon early Wednesday, creating a 16-foot crater in a rare man-made collision with the lunar surface. The rocket part weighs more than 8,000 pounds and is traveling at about 5,000 mph. The impact is expected to occur at approximately 5 a.m. ET, according to experts. The collision may be visible from Earth with telescopes, giving scientists and skywatchers a chance to observe the event. The exact time and visibility depend on location and weather conditions, but researchers are hopeful that the impact will provide valuable data. This is one of the few known instances of a human-made object unintentionally striking the moon.