You can now.
17P is the designation for Comet Holmes, a comet that has unexpectedly brightened in the last couple of weeks.
Astronomers say you'll be able to see it tonight in the sky without any help, though some binoculars would show more details. And the show might go on for a few more weeks, maybe months.
Sky and Telescope magazine is keeping track of the comet's visability. And cometography.com has some historical information and an explanation of why we can see Comet Holmes. Plus, plenty of pics.