Comet 21P/Giacobini-Zinner, or simply "21P," will make its closest approach to Earth on September 10th. A good pair of binoculars or a small telescope should be enough to see it, and be sure to look eastward after midnight to the constellation Auriga.

You can still spot the comet for several nights before and after this close approach, but how long it will stay in sight depends on how powerful your skywatching equipment is. To pinpoint Comet 21P's exact coordinates when observed from any given location or time, check out NASA's ephemeris calculator. (via Space.com)