Orion: The Hunter Becomes the Hunted

Of all the constellations visible in the night sky, Orion "The Hunter" is perhaps one of the most easily recognized.

Straddling the celestial equator, it is well placed for observations this time of year and, unlike many other constellations, it actually looks like its mythological symbol.

The stars outlining the shape of The Hunter are bright and easy to spot and can be used as signposts to other constellations -- but look within its boundaries to find some real treasures.

Perhaps the most famous star marking the north eastern shoulder -- or, more accurately, the armpit -- of the giant hunter is Betelgeuse, a red supergiant star. At magnitude 0.4 it's the second brightest star in Orion and to the naked eye looks distinctly red in color. As a red supergiant, it is nearing the end of its life and in the near future (possibly within the next 100,000 years) it will explode as a supernova, an explosion so great that it will be visible in the daytime sky.

To the opposite corner of Betelgeuse is the blue white star Rigel. To the naked eye this bright supergiant looks like a single star, but telescopic observations reveal a companion star 500 times fainter. Further studies of the light from Rigel's companion star have revealed that it too is a very special binary star called a "spectroscopic binary" meaning its companion is only visible when the spectrum of its light is studied.

Lying directly between the two stars is Orion's famous three star belt. The star at the eastern end of the belt is called Alnitak and is located 817 light-years away. This distance is comparable to the star at the western end called Mintaka, at 916 light-years. The central star, Alnilam, is a distant 1342 light-years away. It's interesting to note that the stars look as if they are at the same distance from Earth as their different brightness compensate for their variation I light-years.

Just to the south of the belt's central star is the jewel of Orion -- the stunning Great Orion Nebula. Looking at that region of the sky with the naked eye will reveal a number of faint stars depicting the hunter's sword and in the middle of them, a faint fuzzy blob. It's a rather mundane description of a beautiful object, but take a look at it through binoculars and you start to see some of the wispy nebulosity. The word nebula is Latin for "cloud" and that's exactly what it is; a vast cloud of gas and dust out of which a new generation of stars are forming.

Read more at Discovery News