Deep Impact
It's going to happen in just over five hours: the Deep Impact space probe will (hopefully) impact the comet Tempel 1 in an effort to learn more about the composition of comets and, by extension, the origin of the universe.
There are a number of live webcasts in the form of video and near-real-time photographs, of the impending collision for all to view on Space.com, Black-Hole.net and the National Optical Astronomy Observatory, among some others.
There are a number of live webcasts in the form of video and near-real-time photographs, of the impending collision for all to view on Space.com, Black-Hole.net and the National Optical Astronomy Observatory, among some others.