Big Dipper Constellation

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The Big Dipper constellation is one of the best known and easiest star asterisms in the night sky to find with the unaided eye. In some countries the asterism is also known as the Plough. It is actually a grouping of the seven brightest stars in the Ursa Major constellation. Five of those stars make up the bulk of the Ursa Major Moving Group. Since two of the stars are moving in the opposite direction of the other five, the look of the Big Dipper constellation will reverse in about 50,000 years.

The Big Dipper constellation is made up of seven stars. Alkaid, Mizar, Alioth, and Megrez make up the handle while Dubhe, Merak, and Phecda round out the bowl of the dipper. Mizar is actually a binary star. It is a 2nd magnitude star coupled with a 4th magnitude named Alcor. The two are often referred to as the Horse and Rider and are separated by a mere 12 minutes of arc. Mizar, at a distance of 78 light years from the Sun, and Alcor at 81 light years, are members of the nearest star cluster to the Sun, the Ursa Major moving cluster (Collinder 285).

Not only do the stars within the Big Dipper constellation have some interesting stories of their own; they also can help you to find other stars and deep space elements. Polaris is found by imagining a line from Merak to Dubhe and then extending it for five times the distance between the two Pointers. Extending a line from Megrez to Phecda, on the inside of the bowl, will lead you to Regulus and Alphard. If you pull out your telescope and follow a line from Phecda to Megrez and continuing on for the same distance again, you will find the Hubble Deep Field.

The constellation that contains the Big Dipper constellation, Ursa Major, was described by ancient astronomers like Ptolemy and is one of the 88 officially recognized constellations in the night sky. According to an ancient Greek myth Zeus fell in love with a mortal woman named Callisto, who was a far-traveler and a huntress. His wife Hera became jealous, and changed Callisto into a large bear. When Callisto failed to return after a long journey, her son Arcas set out to find her, and in a forest one day met a huge bear. To his horror, the bear started to run toward him. Not knowing that it was his mother, Arcas fit an arrow to his bow and was about to slay the bear, when Zeus, to avert the impending tragedy, changed Arcas into a smaller bear. Then Zeus grabbed both bears by the tails, swung them around, and hurled them into the sky where they would be safe and immortal. Hera had the last word, though. She moved them to the portion of the sky that never sets, so that until the end of the world Callisto and Arcas must endure weariness without rest.

Try the links here and here to get some more information about the Big Dipper constellation. Here on Universe Today we have a great article about the top five celestial objects that anyone can see with a small telescope. Astronomy Cast offers a good episode about which star might be the Christmas star.

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