Little Dipper

StarDate: April 4, 2010

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If you take your camera outside on any clear night of the year, put it on a tripod, and snap a long-exposure image of the northern sky, you'll get a picture of lots of colorful arcs -- trails of starlight. But one star won't leave a trail -- it sits still while all the other stars wheel around it. That's Polaris, the North Star. It marks the north celestial pole -- the point in the sky that Earth's axis aims at.

Polaris anchors the entire northern sky. And it also anchors a famous but faint star pattern: the Little Dipper. At nightfall tonight, the dipper stretches roughly parallel to the northern horizon, with Polaris at the tip of the handle and the bowl to its right.

Polaris is hundreds of light-years away. The fact that it looks so bright means that it really is a bright star -- it's far brighter and bigger than the Sun.

The stars at the other end of the dipper -- at the outer edge of its bowl -- are also impressive.

The brighter of the two, Kochab, is at the top of the bowl. It's an orange giant -- a star that's puffed up as it nears the end of its life. The Sun will go through this same process in several billion years.

And below Kochab is Pherkad, a blue-white giant that's almost 500 light-years away. So the light you see from Pherkad tonight has been traveling toward Earth since the early 16th century.

Look for these stars spinning around Polaris throughout the night. The best view comes under a dark country sky.

Script by Damond Benningfield, Copyright 2010

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