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Bear Watcher

August 27, 2012

This is one of the best times of year to watch the Big Dipper. It’s in the northwest at nightfall, with its bowl a little below the handle. It looks as though it’s about to scoop up a big bowlful of stars.

Using the bowl’s handle, you can use one of skywatching’s most famous directions to find one of the sky’s brightest stars: Arc to Arcturus. In other words, follow the curve of the handle until you come to the brilliant yellow-orange star Arcturus, which is well up in the west as night falls. It’s the brightest true star in the sky on summer evenings, and there are no other bright stars around it, so it’s hard to miss.

In skylore, there’s a connection between Arcturus and the dipper. The dipper’s stars are the brightest members of Ursa Major, the great bear. And the name “Arcturus” means “the bear watcher.” As the stars rotate across the night sky, Arcturus always follows Ursa Major, so skywatchers imagined that the star was keeping an eye on the bear.

There’s no real association between Arcturus and the bear, though. Arcturus is only 37 light-years away, while the seven bright stars that outline the Dipper are all at least twice that far.

And for skywatchers, there’s one other important difference. Arcturus will set not long after midnight tonight. But for much of the northern hemisphere, the dipper never sets. So for awhile, the bear can roam freely — without the watchful eye of the bear watcher.

More about Arcturus tomorrow.

Script by Damond Benningfield, Copyright 2012


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