Ursa Minor

Ursa Minor (Latin: "Smaller Bear", contrasting with Ursa Major), also known as the Little Bear, is a constellation in the northern sky. Like the Great Bear, the tail of the Little Bear may also be seen as the handle of a ladle, hence the name Little Dipper. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations. Ursa Minor is notable as the location of the north celestial pole, although this will change after some centuries due to the precession of the equinoxes. Polaris, the brightest star in the constellation, is a yellow-white supergiant and brightest Cepheid variable star, ranging from apparent magnitude 1.97 to 2.00. Beta Ursae Minoris is only slightly fainter, with its apparent magnitude of 2.08. Also known as Kochab, it is an orange giant star, 16 degrees from Polaris. It and magnitude 3 Gamma Ursae Minoris have been called the 'guardians of the pole star'. Three stellar systems have been discovered to contain planets. ... Ursa Minor is notable as the location of the north celestial pole, although this will change after some centuries due to the precession of the equinoxes. It is bordered by Camelopardalis to the west, Draco to the west, and Cepheus to the east. Covering 256 square degrees, it ranks 56th of the 88 constellations in size. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is 'UMi'. ... Stars. Ursa Minor is colloquially known as the Little Dipper because its seven brightest stars seem to form the shape of a dipper (ladle or scoop). The star at the end of the dipper handle is Polaris, the North Star. Polaris can also be found by following a line through the two stars that form the end of the "bowl" of the Big Dipper, a nearby asterism found in the constellation Ursa Major. The four stars constituting the "bowl" of the little dipper are unusual in that they are of second, third, fourth, and fifth magnitudes. Hence, they provide an easy guide to determining what magnitude stars are visible, useful for city dwellers or testing one's eyesight. ... Marking the Little Bear's tail, Polaris, or Alpha Ursae Minoris, the brightest star in the constellation, is a 'yellow-white' supergiant that varies between spectral types F7Ib and F8Ib, and located around 430 light-years away from Earth. Varying between apparent magnitude 1.97 and 2.00 over a period of 3.97 days, it is the closest Cepheid variable star to Earth. Beta Ursae Minoris, traditionally called Kochab, is only slightly less bright than Polaris. It is an orange giant—a evolved star that has used up the hydrogen in its core and moved off the main sequence—of spectral type K4III. ... Gamma Ursae Minoris, traditionally known as Pherkad, has an apparent magnitude that varies between 3.04 and 3.09 roughly every 3.4 hours. ... Delta Ursae Minoris is a white main sequence star of spectral type A1V with an apparent magnitude of 4.35 located around 176 light-years from Earth. ... A triple star system, Epsilon Ursae Minoris shines with a combined average light of magnitude 4.22. A yellow giant of spectral type G5III, the primary is an RS Canum Venaticorum variable star. ... Deep-sky objects. Ursa Minor is rather devoid of many deep-sky objects. A notable object is the Ursa Minor Dwarf, a dwarf galaxy, located in the area of the constellation. Meteor showers. The Ursids are Ursa Minor's prominent meteor shower and peak between December 18 and 25. Its parent body is the comet 8P/Tuttle. [Ursa Minor. Wikipedia]