There’s a Bear Up There!

The other night we decided to do a little late spring stargazing. The sky was fairly dark and clear, and the stars were bright.  We went out on the deck and looked up. There, almost directly overhead was the Big Dipper.

Back when I used to give star lectures in the planetarium, I’d always start the audience out at the Big Dipper and work my way around the sky from there. For northern hemisphere stargazers, it’s one of the most recognizable star patterns.

The Big Dipper is really an asterism — that’s because it’s part of a larger constellation called Ursa Major, the Greater Bear. The figure here sort of looks like a bear striding across the sky and the dipper is on his back. In other parts of the world, people call the Dipper by the name of “the Plough. Other cultures throughout time have assigned meaning to the stars, from the Greeks to various Asian cultures and even throughout the native groups living in North America.

There are a couple of useful things you can do with the Dipper — well, three actually. The first thing you can do is admire it. It’s a pretty striking shape that our human brains have assigned to it.  The second thing you can do with it is test your eyesight. After you’ve gotten good and dark-adapted to the night sky (which takes around 10-2o minutes, look up at the bend in the handle of the Dipper. There are two stars there, and if your eyesight is good, you should be able to make them out. They’re called Alcor and Mizar.  There are actually six stars in that little region of space, but they’re too faint to make out with the naked eye.  Try checking out this pair with binoculars or a telescope.

The third thing you can do is find north. The way to do this is to locate the end stars in the cup. These are called Mirak and Dubhe.  If you start at Merak and trace a line through Dubhe and continue it on out, you will eventually run into the North Star, also known as Polaris.  That’s the star that our north pole appears to point to and indicates true north.

The Big Dipper is often the first star pattern that people learn (at least in the Northern Hemisphere) when they begin stargazing. It’s not a bad start. Once you learn it, you can branch your way out to other constellations pretty easily.  Over the next few entries, I’ll share a few more with you! In the meantime, point your browser here if you want to know more about Ursa Major and the Big Dipper.