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Comet PanStarrs

March 4, 2013

A comet that was discovered while still in the deep freeze of the outer solar system is thawing out as it approaches the Sun. That may make it visible to the unaided eye next week, quite low in the west after sunset.

Comet Panstarrs was discovered two years ago by a robotic telescope that scans for objects that might come close to Earth. The comet will pass closest to Earth tomorrow, but at a healthy range of a hundred million miles. It’ll pass closest to the Sun on Sunday, at just 30 million miles.

As a comet approaches the Sun, the heat vaporizes some of the ice at its surface, spewing gas into space. That releases small solid particles as well. This material spreads out to form a giant cloud around the comet’s tiny nucleus. The Sun pushes some of this material away from the comet, creating a long, glowing tail.

Unfortunately, though, it’s impossible to predict how much material will spew into space, and how bright it will make the comet appear. As we recorded this episode, experts were predicting that Panstarrs could become bright enough to see with the unaided eye. The comet wasn’t getting as bright as early estimates, though, so we can’t tell you exactly how bright it’ll be. It’ll peek into view early next week, quite low in the western evening twilight. It’ll be close to the Moon on the 12th and 13th, making it easier to pick out.

Even if you can’t see Panstarrs with the eye alone, it should still be a good sight through binoculars. We’ll post an update online at


Script by Damond Benningfield, Copyright 2013

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