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Western Slope Skies 10/25/13

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Did you know that the Big Dipper is NOT a constellation?  It’s actually an asterism - a pattern of stars in the sky, much like a pattern of clouds.  

While there are many asterisms that are commonly known, none of them are constellations.  Other fall and winter asterisms include the Little Dipper, the Winter Hexagon, and the Great Square of Pegasus.

The Big Dipper is part of the constellation, Ursa Major, the Great Bear.  What most people see as the handle of the Big Dipper is the tail of the bear, while the bowl of the dipper is part of the body of the bear. 

Constellations are regions of the sky with defined borders and are a map of the sky.  There are 88 official constellations, as defined by the International Astronomical Union in 1930.

Colorado consists of 64 counties.  A map of these counties completely defines the state of Colorado.  In a similar fashion, the 88 constellations completely define the sky.  With the exception of the Sun, every star in the sky is in one and only one constellation, just as every city and town in Colorado is in one and only one county.

Because the Earth orbits the Sun during a year, the Sun appears to us to move through different constellations. 

Constellations and asterisms are important, because they help us navigate around the night sky.  We often use pointer stars to find our way to other objects.  For example, we use the two end stars on the Big Dipper to find our way to Polaris, the North Star. 

If you would like to learn more about the constellations, just visit this link from the International Astronomical Union.

Since there are no official asterisms, YOU can define one.  If you see a pattern of stars in the sky that looks like an object, that's an asterism.  Give it a name…maybe it will catch on.