Ursa Major Ursa Major, the Greater Bear, is a northern constellation that includes the Big Dipper asterism. Hold your mouse cursor over the image to see constellation figures, boundaries, and star identifications. Ursa Major has been associated with a bear by many different cultures and its mythology may date back as far as 13,000 years ago. The two end stars in the bowl of the Big Dipper, Dubhe and Merak, are the "Pointers". They can be used to find Polaris (Alpha Ursa Minoris), the North Star, by drawing a line from Merak to Dubhe and extending it to Polaris. Alpha Ursae Majoris is Dubhe. It is the second brightest star in the constellation. It is a spectral-class K-type orange giant star that shines at an apparent magnitude of 1.81. It is located 124 light-years away from the Earth. Beta Ursae Majoris is Merak. It is a spectral-class A-type blue-white star that shines at an apparent magnitude of 2.34. It is located 79 light-years away from the Earth. Epsilon Ursae Majoris is Alioth, the brightest star in the constellation. It is a spectral-class A-type blue-white star that shines at an apparent magnitude of 1.76. It is located 81 light-years away from the Earth.
The second star from the end of the handle of the Big Dipper, Zeta Ursae Majoris, is the double star Mizar and Alcor, a test of eyesight, although in reality visually splitting them with the unaided eye is not that difficult at all. These two stars, magnitude 2.2 and 4 respectively, are separated by 11.75 arcminutes and known as the "Horse and Rider". Alcor is also designated as 80 Ursae Majoris. Mizar itself is a double star. Mizar A shines at magnitude 2.27 and Mizar B shines at magnitude 3.95. Mizar A and B are separated by 14 arcseconds and easily resolved in a small telescope. Mizar was the first known double star, discovered in 1617 by Benedetto Castelli. Mizar A was the first spectroscopic binary to be discovered, by Pickering in 1889. Mizar B also is a spectroscopic binary. So the Mizar and Alcor system actually consists of 5 stars. All of the stars involved are members of the Ursa Major Moving Cluster and are located 83 light-years from Earth. The star Sidus Ludoviciana, halfway between Alcor and Mizar, is a field star that is not part of the Mizar and Alcor system. It shines at magnitude 8. It was discovered by Johann Georg Liebknecht in 1722. Liebknecht erroneously thought it was a planet and named it after Louis V, Landgrave of Hesse-Darmstadt. A Landgrave is a title similar to a Duke. The stars in the Big Dipper, except for Dubhe and Alkaid (Eta Ursae Majoris), are part of Collinder 285, the Ursa Major Moving Cluster. All of these stars probably formed at the same time 300 million years ago, and are now moving together through space in the same direction with similar velocities. Ursa Major lies far away from the Milky Way so it doesn't contain any emission nebulae, but it does have a number of spectacular galaxies, such as M81 and M82, M101, M108, and the Arp 214 galaxy group. It is also home to M97, the Owl planetary nebula and 8C 0958+561, the Twin Quasar. Ursa Major was cataloged by the Greek astronomer Ptolemy in the second century C.E. (Common Era). It is the third largest of today's 88 modern constellations, covering 1,280 square degrees of sky. Canes Venatici The constellation of Canes Venatici represents the Hunting Dogs of Boötes, the Herdsman, which lies to the southeast of Ursa Major. Alpha Canum Venaticorum is Cor Caroli. It is a spectral-class A dwarf star that is located 110 light-years away. It is a variable star whose magnitude ranges from 2.84 to 2.98. It is also a double star. The secondary is a 5.6 spectral-class F dwarf that is 19 arcseconds distant. Cor Caroli was originally named Cor Caroli Regis Martyris, the "Heart of Charles the Martyred King", named after King Charles I of England who was executed after the English Civil War. Beta Canum Venaticorum is Chara, a spectral-class G star that shines at magnitude 4.24 and is located 27 light-years away. Y Canum Venaticorum is La Superba, a spectral-class C carbon star that is very red in color. Its magnitude varies from 4.8 to 6.3 over a 160-day period. It is located 711 light-years from Earth. Canes Venatici contains globular cluster Messier 3, Messier 51, the Whirlpool Galaxy, Messier 63, the Sunflower Galaxy, spiral galaxy Messier 94, and NGC 4631 and NGC 4656, the Whale Galaxy and the Golf Club galaxies. Canes Venatici was introduced by Polish astronomer Johannes Hevelius in 1687. It is the 38th largest of today's 88 modern constellations, covering 465 square degrees of sky. Leo Minor Leo Minor, the Lesser Lion, is a northern constellation that does not have any ancient myths associated with it. Leo Minor lies between the constellations of Leo, the "Larger Lion", and Ursa Major, the "Great Bear." The brightest star is 46 Leonis Minoris, known as Praecipua. It does not have a Bayer designation. It is a spectral-class K orange star on its way to becoming a giant. It shines at magnitude 3.83 and is located 98 light-years away from Earth. Its name in Latin means the "Chief" star of Leo Minor. Beta Leonis Minoris is the second brightest star in the constellation at magnitude 4.21. It is a binary star comprised of spectral-type G and F stars whose magnitudes are 4.40 and 6.12 that is located 146 light-years distant. The pair is separated by 0.25 arcseconds at maximum separation, and 0.1 arcseconds at minimum separation with a 38.62-year period. Leo Minor does not contain any Messier objects although it does contain some NGC galaxies. It also is home to Hanny's Voorwerp, a relatively bright blob of matter that is associated with galaxy IC 2497. The object may be the size of the Milky Way Galaxy. It is located 650 million light-years distant. Leo Minor was introduced by Polish astronomer Johannes Hevelius in 1687. It is the 64th largest of today's 88 modern constellations, covering 232 square degrees of sky. North is to the lower left in the above image.
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