On July 3, 2005(Seattle time) NASA slammed a space probe into Comet Tempel 1. While the

comet was not visible to the naked eye, it was visible through telescopes. Here is an animation I

did of a before and after impact of the comet. The six frames are not exactly the same due to

telescope movement and atmospheric unsteadiness, but you can clearly see the comet brighten.

The first exposure ended at 10:48 PM PDT. The second frame is after impact ended at 10:56 PM

PDT. As the frames progress, the comet brightens. Click on the image to see the animation and

give it time to load.. (In two frames there is a meteor trail) The comet is near the bottom center. In

the Solar System section of the site is another image of the comet presented as a long time

exposure to show the brightening at impact.