Special | 54m 41s
In this show, scientists around the world follow a once-in-a-lifetime event, the path of the sun-grazing comet ISON. The comet, somewhere between one and 10 kilometers in diameter, is currently just beyond the orbit of Jupiter. As it races past Earth toward the sun, it will likely develop a tail to light up the night skies.
Expired: 03/16/15Video has closed captioning.