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There's a green comet in the night sky this St. Patrick's Day

If you end up seeing trails after the Irish celebration, make sure it's not the coma of a rare visit from a steamy space rock.

41p.jpg

Save a pint of Guinness for this party crasher.

Eric Mack

If you plan to party on St. Patrick's Day this Friday, make sure you can still see straight in order to spot a rare comet visit.

Comet 41P/Tuttle-Giacobini-Kresak will be visible tonight and it's been getting brighter and greener just in time for the holiday.

If you're in the northern hemisphere with dark, clear skies, you may be able to spot the festive space snowball. Make sure you're ready with a telescope -- or perhaps even a good set of binoculars.

According to amateur astronomer Bob King writing for Sky and Telescope, you should look for the comet any time after dark by first locating the star Merak, which makes up both the back paw of the constellation Ursa Major and the lower front (as in, away from the handle) star in the "big dipper."

Over the next week or so, the comet will slowly move up through the middle of that dipper's bowl, but on Friday evening you'll be able to find it beneath the base of the bowl, just like in my crude illustration below:

Where to look for a St. Paddy's Day comet.

NASA/Eric Mack/CNET

Of course, glowing green isn't exactly rare for a comet: That's often an indication that it's burning through gases such as diatomic carbon rather than avoiding being pinched. Still, a glowing green comet on St. Patrick's Day doesn't happen every year and this particular comet only visits the inner solar system every five to seven years.

Clearly, Comet 41P is trying to crash Earth's epic St. Paddy's day bash on this visit, because the tail-wagging space rock will come closer to our planet in the next few weeks than it has at any time in over a century.

That said, it might be better if we don't offer it an official invite to any Irish gatherings this weekend, as comets are known to make a spectacular entrance and totally trash the place in the process. Just ask the dinosaurs.

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