By now you should be able to find and recognize Orion, the most easily identifiable winter constellation, almost instinctively.  After you have located it in the south southwest, locate the star Rigel.  From here move your gaze far to the left and slightly down until you encounter an extremely bright star; indeed, this star will be the brightest one in the entire sky!  It is Sirius, The Dog Star in the constellation Canis Major, The Greater Dog.  Canis Major is the larger of Orionís hunting dogs.  Sirius is the dogís left eye.  Sirius is not only the brightest star in the winter night sky, it is the brightest star visible for observers at northern latitudes of 32 degrees and higher.  It is one of the closest stars to Earth at a distance of 8Ĺ light-years (Consult the glossary at the end of this section for a definition of a light-year).  Alpha Centauri is closer at 4.3 light-years and appears brighter, but it is only visible in northern latitudes below 30 degrees and south of the equator. 

Having located Canis Major, use Figure 17 to find the fainter stars within that constellation. 

Letís go back to Orion.  Specifically, locate the middle star in Orionís belt and make an imaginary line between this star and Betelgeuse.   Continue the line to the northeast for approximately three times the distance between the belt star and Betelgeuse.  At this distance you will see a star which is about the same brightness as the stars in Orionís belt.  If you have stopped at the correct star, you will see a brighter star to its left and downward at about a 45 degree angle as shown in Figure 17.  In fact, the distance between the brighter and the fainter star will be about the same as the length of Orionís belt.  The fainter star is called Castor while the brighter star is called Pollux.  They are the most famous stars in the constellation of Gemini, The Twins.  Further examine Figure 17 so that you can pick out the rest of primary stars in the constellation. 

Itís time to use Orion again!  Make an imaginary line between Rigel and the leftmost star in Orionís belt.  Extend the line about four times that distance to the eastward where you should run upon a star that is about as bright as Rigel.  It is the star Procyon (pronounced pro sie on) in the constellation Canis Minor, The Lesser Dog.  The constellation is very small with only a few other visible stars. 

As indicated by Figure 17, in between Procyon and Sirius are the faint stars of the constellation Monoceros, The Unicorn. 

The zero magnitude stars Capella, Aldebaran, and Rigel (which we learned how to locate last month) along with the other bright stars Sirius, Procyon, and Pollux form an enormous six sided shape in the heavens formally known as The Winter Hexagon.  It is a structure that is so easily recognizable after youíve seen it once, that it will become your primary navigation aid in the winter sky.  It will be especially useful when we delve into the sky of March.


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