The probe, Deep Impact, will impact with Comet Tempel 1 at 7:52 pm on July 3. If you’re interested in this sort of thing, be sure to get out your telescopes or binoculars, the ejection of dust and material from the comet will not be visible with the naked eye. The ejection is expected to happen somewhere between Jupiter and Spica in the sky, so make sure you’re watching!