We probably won’t have to wait half a century to see another bright comet. Unfortunately, astronomers can’t tell us when the next great one will appear. Halley is the only short-period comet that regularly becomes bright enough to be obvious with unaided eyes. The most spectacular of these dust-rich balls of frozen gas are making their initial trips through the inner solar system. As their ices are exposed to intense sunlight for the first time, they erupt with activity and often grow long tails.
The list of dazzling newcomers since Halley last appeared in Earth’s sky includes C/1995 O1 (Hale-Bopp), C/1996 B2 (Hyakutake), and C/2006 P1 (McNaught). Over the past few centuries, Earth has averaged roughly one bright comet every decade. So, expect to see at least a few more before Halley makes its next foray into the inner solar system — we just can’t tell you when they will arrive. — Richard Talcott, Senior Editor