A defunct part of a Falcon 9 rocket could slam into the moon at more than 5,000 miles per hour, according to scientists.

A discarded upper stage of SpaceX's Falcon 9 rocket is expected to collide with the Moon on August 5 in what researchers describe as a rare scientific event rather than a planetary threat. Although the impact is accidental,

Part of a SpaceX rocket will crash into the moon early Wednesday and could be visible by telescope from the U.S. Here's when it will happen. (AP Photo/John Raoux)

How do we know a SpaceX rocket will crash into the moon? The rocket's projected impact into the moon's near side – the side permanently facing Earth – was predicted by Bill Gr