Once-in-a-lifetime comet comes around.

Watch the skies next year, warns Scientific American, or you’ll miss something you’ll never see again:

As it flares out of the distant Oort Cloud, the newly discovered comet C/2012 S1 (ISON) appears to be heading on a trajectory that could make for one of the most spectacular night-sky events in living memory.

After it loops around the Sun and forms this tail, the comet should then pass relatively close to Earth—not near enough to cause any worry, but close enough to put on a great show. Viewers in the Northern Hemisphere will get the best view as the comet blooms in the weeks approaching Christmas 2013. The comet could grow as bright as the full moon.

The comet expert John E. Bortle is already comparing ISON with the Great Comet of 1680, which, according to contemporary accounts, caused the people of New York’s Manhattan Island to be “overcome with terror at a sight in the heavens such as has seldom greeted human eyes…. In the province of New York a day of fasting and humiliation was appointed, in order that the wrath of God might be assuaged.”

As long as it doesn’t wind up turning everyone outdoors into piles of red dust, I’ll be excited.