Orion Orion, the Hunter, is one of the most famous and distinctive constellations in the night sky. Its mythology dates to the late bronze age, thousands of years ago. Hold your mouse cursor over the image to see constellation figures, boundaries, and star identifications. The Sumerians associated Orion with the myth of Gilgamesh, a hero who fought the bull of Heaven, represented by the constellation of Taurus. Red-giant star Betelgeuse is at the top-center of the photo, and blue-white Rigel is at bottom center. Between Betelgeuse and Rigel are the three distinctive, bright, second-magnitude stars in a row, Alnitak, Alnilam and Mintaka, that make up the belt of Orion. Alpha Orionis is Betelgeuse, the ninth brightest star in the night sky. It is a spectral-type M red supergiant semi-regular variable star that varies in magnitude from 0.42 to 1.3. It is located 427 light-years away from Earth. Beta Orionis is Rigel, the seventh brightest star in the night sky. Rigel is a spectral-type B blue supergiant that sines at magnitude 0.12 and is located 860 light-years away. Rigel is a double star with its companion, Rigel B, located 9 arcseconds away. Although it is not particularly close, it can sometimes be difficult to spot Rigel B, which shines at magnitude 6.7, because of the dazzling brightness of Rigel A. Rigel B itself is a spectroscopic binary, making Rigel a triple-star system. Delta Orionis is Mintaka, the westernmost star in the belt of Orion. It is a spectral-type O blue giant that sines at magnitude 2.14 and is located 916 light-years away. Epsilon Orionis is Alnilam, the middle star in the belt of Orion. It is a spectral-type B blue supergiant that varies in magnitude from 1.64 to 1.74 and is located 1,300 light-years away. Zeta Orionis is Alnitak, the easternmost star in the belt of Orion. It is a spectral-type O blue supergiant that sines at magnitude 2.04 and is located 736 light-years away. This area of the sky is filled with enormous red emission nebulae, part of the Orion Molecular Cloud, and is the birthplace of stars. Most of the nebulae shine in the light of ionized hydrogen, powered by hot young stars that have formed out of the gas clouds. Just below the belt next to Alnitak is the nebulous complex containing B33 and NGC 2024, the Horsehead Nebula and Flame Nebulae. Below that lies M42, the Great Nebula in Orion. The largest emission nebula in the photo is Sh2-276, Barnard's loop, seen as a semi-circle around the belt and sword of Orion. The next largest nebula is Sh2-264, the Angelfish Nebula, which surrounds Meissa (Lambda Orionis). The small bright red emission nebula at the upper left of the photo is NGC 2237, the Rosette Nebula, and above it, the faint complex of nebulosity containing NGC 2264, the Cone Nebula. To the left in Monoceros is IC 2177, the Seagull Nebula. A large but extremely faint blue reflection nebula, IC 2118, the Witch Head, is located just to the right (west) of Rigel. From our vantage point on Earth, as we look at the Milky Way in the winter night sky, we are looking in the opposite direction from the center of our galaxy. Because the direction of the center of our galaxy contains so much more dust, star clouds and dust lanes appear more red in color in the summer Milky Way in Sagittarius than in the winter Milky Way near Orion. Orion was cataloged by the Greek astronomer Ptolemy in the second century C.E. (Common Era). It is the 26th largest of today's 88 modern constellations, covering 594 square degrees of sky. Monoceros Monoceros, the Unicorn, follows Orion in the night sky. It is located between Canis Minor to the northeast, Canis Major to the south, Gemini to the north and Hydra to the east. The figure of Monoceros can be difficult to distinguish as it contains only a few fourth magnitude stars, none of which have proper names, but it is home to some wonderful deep-sky objects. Alpha Monocerotis, the brightest star in the constellation, is a spectral-type K orange giant that shines with an apparent magnitude of 3.94. It is located at a distance of 144 light-years from Earth. Beta Monocerotis is a beautiful triple-star whose members form a fixed triangle. They are designated as Beta Monocerotis A, B and C. All three are spectral-type B hot blue-white stars located 690 light-years away. Beta Monocerotis A has an apparent magnitude of 4.6. Beta Monocerotis B has an apparent magnitude of 5.4. Beta Monocerotis C has an apparent magnitude of 5.6. Stars B and C are separated by 2.8 arcseconds. Star A is separated from that pair by 7.4 arcseconds. William Herschel, who discovered Beta Monocerotis in 1781, called it "one of the most beautiful sights in the heavens." Monoceros is also home to the large, bright and beautiful NGC 2237 (Rosette Nebula) , the fascinating NGC 2264 (Cone Nebula), IC 2177 (the Seagull Nebula), NGC 2261 (Hubble's Variable Nebula), and the very faint complex of nebulae which includes NGC 2170 (the Angel Nebula). Monoceros was introduced by Petrus Plancius, a Dutch astronomer and cartographer, in 1612. It is the 35th largest of today's 88 modern constellations, covering 482 square degrees of sky. Canis Minor Canis Minor, the Lesser Dog, is one of Orion's hunting dogs. Along with Canis Major, it follows faithfully behind Orion in the sky. Alpha Canis Minoris is Procyon, the brightest star in Canis Minor. Its name means "before the dog" in Greek because it rises before Sirius, the Dog Star. It shines at an apparent magnitude of 0.40 and has a spectral-class of type F. It is located 11.4 light-years away, which is why it is so bright, being the eighth brightest star in the night sky. Beta Canis Minoris is Gomeisa, which means "the little bleary-eyed one" in Arabic. Gomeisa is a Gamma Cassiopeiae-type variable star that ranges in apparent magnitude from 2.84 to 2.92. It is a blue-white spectral-class B type main sequence star located 162 light-years away. Canis Minor does not contain any Messier objects. Canis Minor was cataloged by the Greek astronomer Ptolemy in the second century C.E. (Common Era). It is the 71st largest of today's 88 modern constellations, covering 183 square degrees of sky. North is to the top in the above image.
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