Boötes Boötes is a spring constellation that is located between Draco and Ursa Major to the north, Virgo to the south, Coma Berenices and Canes Venatici to the west and Corona Borealis, Serpens Caput and Hercules to the east. Hold your mouse cursor over the image to see constellation figures, boundaries, and star identifications. The name Boötes is derived from Greek meaning "Herdsman" or "Plowman." It is an ancient constellation that goes back to Babylonian times. One version of the Greek myth associated with Boötes is that he was the son of Demeter and drove the plough of Ursa Major with oxen. Alpha Boötis is Arcturus, a brilliant magnitude -0.04 spectral-type K orange-giant star. Arcturus' name in ancient Greek means "Guardian of the Bear", meaning Ursa Major. Arcturus is the fourth brightest star in the night sky, and the brightest in the northern hemisphere. Located at a distance of 36.7 light-years from Earth, it is one of the most luminous stars in the Sun's nearby vicinity along with Vega and Sirius. Scientists believe that Arcturus may have exhausted its hydrogen fuel and started fusing helium. It will continue to expand before expelling its outer atmosphere and eventually ending its life as a white dwarf. Epsilon Boötis is Izar, the second brightest star in Boötes. It is a beautiful double star that its discoverer, German astronomer Friedrich Georg Wilhelm von Struve called Pulcherrima, which means the "Loveliest." Izar is comprised of a magnitude 2.70 spectral-class K orange-giant primary star and a magnitude 5.12 secondary that is a spectral-class A white star located 3 arcseconds away from the primary. Their combined brightness is magnitude 2.37. There is a striking color contrast effect of visual perception that makes the pair very colorful. The Izar system is located 210 light-years away. Eta Coronae Borealis is the very tight visual binary star HD 137107. It is comprised of components with magnitude of 5.6 and 5.9 that are separated by just 0.67 arcseconds. With stars of similar brightness involved, this is an excellent challenge object for scopes six inches and larger. Good seeing and good optics are required to split this double star. Boötis does not contain any Messier objects. It lies far from the plane of the Milky Way Galaxy, so it does not contain any star clusters or nebulae, but it does contain some galaxies. Boötes was cataloged by the Greek astronomer Ptolemy in the second century C.E. (Common Era). It is the 13th largest of today's 88 modern constellations, covering 907 square degrees of sky. Corona Borealis Corona Borealis is the Northern Crown. It is a small but distinctive constellation located between Hercules and Boötes. Alpha Coronae Borealis is Alphecca, a spectral-class A type variable star that ranges magnitude 2.21 and 2.32 and is located 74 light-years away. Beta Coronae Borealis is Nusakan, a spectral-class A type variable star that ranges magnitude 3.65 and 3.72 and is located 114 light-years away. Eta Coronae Borealis is a challenging double star for observers. It is comprised of two spectral-type G class dwarfs of similar magnitudes. Eta Coronae Borealis A is magnitude 5.64, and Eta Coronae Borealis B is magnitude 5.95. They are separated by 0.67 arcseconds with a period of 41.63 years. They are located 58 light-years from Earth. Excellent seeing is required to split this tight pair of stars, but their similar magnitudes make it easier than a close pair with more widely varying magnitudes. R Coronae Borealis is a yellow supergiant star that is an irregular eruptive variable whose magnitude ranges from 5.7 to 14.8 over irregular time periods. Corona Borealis was cataloged by the Greek astronomer Ptolemy in the second century C.E. (Common Era). It is the 73rd largest of today's 88 modern constellations, covering 179 square degrees of sky. North is to the top left in the above image.
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