Comet ISON's journey from outside the solar system toward the sun reaches its crescendo Thursday, and you can follow along live through a NASA live webcast.
The comet will pass less than 700,000 miles from the sun's surface. Scientists and amateur astronomers will be paying close attention to any available observations of the comet to see if it survives its first close encounter with a star.
If it stays together, it could mean some spectacular skywatching in December. But it's possible that the comet's nucleus of dust and ice could break into pieces or disintegrate.
Appearing on the webcast to discuss the comet will be several solar physicists, a comet scientist, and the astronomy blogger for Slate.
Tune in here from 1 p.m. to 3:30 p.m.