The Lunar Crater Observation and Sensing Satellite (LCROSS) is due to impact the Moon early Friday morning.
NASA has published a LCROSS Viewer's Guide if you want to try to watch it.
Not only is the spacecraft impacting the moon, but the shepherding upper stage will also crash. The goal is to look for water in the particulates thrown up by the impacts.
Oddly, the Drudge Report headline was "NASA to bomb the moon"