The Geminid meteor shower—which should be the year's most impressive, according to astronomers—peaks tonight. If skies are clear where you live, be sure to go outside and look up. NASA's Bill Cooke predicts that this 2012's shower will be extra luminous. Why? Because it's coinciding with yet another meteor shower. "The source of the new shower is Comet Wirtanen," says Cooke. "Dust from this comet hitting Earth's atmosphere could produce as many as 30 meteors per hour."

The Geminids are an annual occurrence, which is somewhat strange amongst meteor showers. Usually these events happen when a comet hurtles past Earth, trailing a bunch of space debris that burns up in the Earth's atmosphere. The Geminids, on the other hand, have been observed like clockwork every year since the mid-1800s and they're not produced by a comet. The stellar object responsible is called 3200 Phaethon. BoingBoing's Maggie Koerth-Baker explains:

... at this point most scientists think it's probably an asteroid, which then leads to still-yet-unexplained question of where all the meteors come from. Asteroids, after all, do not typically accumulate tails of small rocks. So far, the best guess has to do with 3200 Phaethon's orbit, which over the course of about a year and a half takes it closer to the Sun than Mercury and then back out further from the Sun than Mars. Those wild temperature swings might lead to the asteroid cracking and throwing off dust and debris, which then becomes meteors.

Even that explanation doesn't account for the sheer number of meteors visible every year, Koerth-Baker notes. Whatever's causing the Geminids, the best time to view this stellar light show should be around 3:00 a.m. local time, though the meteors may stay visible through Dec. 16. For those of us afraid of venturing out at night, NASA has set up this live-stream for our stargazing pleasure: