Close Encounters Of The Comet Kind

This weekend will be a busy one for astronomers and stargazers alike. A penumbral eclipse kicks off Friday night.

Beginning in early evening, the earth will pass between the sun and the moon, covering the moon with its light, outer shadow or penumbra — hence the name. The effect will be only a very slight dimming of the moon that's barely noticeable to the untrained eye.

Then on Saturday, beginning at 2:00 a.m., comet 45P will pass just 8-million miles away from earth. It may sound like a ways off, but that's almost too close for comfort, according to Wake Forest University Physics Professor Greg Cook. This comet — nearly a mile across — will be zooming by the earth at more than 51-thousand miles per hour. Cook says when it gets close enough to the sun tomorrow morning, stargazers may be rewarded looking eastward about 30 degrees above the horizon.

"You'll see sort of a fuzzy object, the center of which is an actual icy, rocky, core," says Cook.  "But there's a big gassy atmosphere around it, and a lot of that gassy atmosphere gets blown back creating a very long tail. And these things can be tens of degrees long in the sky."

Cook says visibility will depend on your proximity to bright city lights, and the light from tonight's full moon. He says it'll be tough to spot with the naked eye, so he recommends using binoculars or a telescope. But if you miss comet 45P Saturday morning, fret not. The “P” stands for periodic, and it'll return this way in about five years from now.