Tomorrow morning at 7:49 am ET, NASA's New Horizons probe will zoom past Pluto, the first time the former planet (and current dwarf-planet) has ever been visited by spacecraft. The probe has already sent back the first images of the tiny planet, which turned out to not be the color we expected it to be.
But NASA has kindly put together an app that will allow us to follow along with a live simulation. You'll have to download and install the app, but hey, how often is this kind of thing going to happen in your lifetime? NASA TV will also host a live-countdown on UStream, starting at 7:30 am ET tomorrow.