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Polaris
Polaris or North Star, star nearest the north celestial pole (see equatorial coordinate system ). It is in the constellation Ursa Minor (see Ursa Major and Ursa Minor ; Bayer designation Alpha Ursae Minoris) and marks the end of the handle of the Little Dipper. Polaris's location less than 1° from the pole (1992 position R.A. 2 h 23.3 m , Dec. +89°14′) makes it a very important navigational star even though it is only of second magnitude; it always marks due north from an observer. Polaris can be located by following the line upward from the two stars (the Pointers) at the right end of the bowl of the Big Dipper or, if the Big Dipper is not visible, by following the line through the left side of the square in Pegasus through the end star in Cassiopeia. The star is a Cepheid variable and oscillates in brightness roughly every four days. Because of the precession of the equinoxes , Polaris will not remain the polestar indefinitely; in 2300 BC the polestar was in the constellation Draco , and by AD 12,000 the star Vega in the constellation Lyra will be the polestar. |
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"Polaris." The Columbia Encyclopedia, 6th ed.. 2008. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. "Polaris." The Columbia Encyclopedia, 6th ed.. 2008. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1E1-Polaris.html "Polaris." The Columbia Encyclopedia, 6th ed.. 2008. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-Polaris.html |
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Polaris
Polaris The north pole star, Alpha Ursae Minoris, magnitude 2.0. It is an F-type supergiant, 431 l.y. away. Polaris is currently less than 1° from the north celestial pole, and the distance is gradually decreasing due to precession; it will be closest to the pole, just under ½°, around the year 2100. Polaris is a Cepheid variable with a period of 4 days and a small range, originally about 0.1 mag. but which decreased during the 20th century to only a few hundredths of a magnitude now. Polaris is also a spectroscopic binary with a period of 30 years. From observations with the Hubble Space Telescope this companion appears to be a dwarf F star. There is a more distant companion of magnitude 8.2 which can be seen with a small telescope.
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"Polaris." A Dictionary of Astronomy. 1997. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. "Polaris." A Dictionary of Astronomy. 1997. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1O80-Polaris.html "Polaris." A Dictionary of Astronomy. 1997. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O80-Polaris.html |
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Polaris
Polaris, the Pole Star, a second-magnitude star in the constellation Ursa Minor that describes a circle of about 2° 25′ daily about the North Pole. It is thus of service to navigators as it points within a degree or two of true north. Corrected by Pole Star tables that are printed in most nautical almanacs the altitude of Polaris can be used to determine latitude. During the 15th century, when celestial navigation was in its infancy, a correction to the observed altitude of Polaris (known in the Mediterranean as Stella Maris, star of the sea) would be made according to the position of the two Guard stars as they encircle the pole of the sky.
See also navigation. |
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"Polaris." The Oxford Companion to Ships and the Sea. 2006. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. "Polaris." The Oxford Companion to Ships and the Sea. 2006. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1O225-Polaris.html "Polaris." The Oxford Companion to Ships and the Sea. 2006. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O225-Polaris.html |
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Polaris
Polaris pəˈlerəs; -ˈlärəs UGM-27 a surface-to-surface solid-propellant ballistic missile that can be launched either from the surface or under water. Like the Poseidon, it is equipped with inertial guidance and nuclear warheads. The three versions produced have ranges, in nautical miles, from 1,200 to 2,500.
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"Polaris." The Oxford Essential Dictionary of the U.S. Military. 2001. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. "Polaris." The Oxford Essential Dictionary of the U.S. Military. 2001. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1O63-Polaris.html "Polaris." The Oxford Essential Dictionary of the U.S. Military. 2001. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O63-Polaris.html |
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Polaris
Polaris the Pole Star; the name comes (in the mid 19th century) from medieval Latin polaris ‘heavenly’, from Latin polus ‘end of an axis’.
Polaris was also the name of a type of submarine-launched ballistic missile designed to carry nuclear warheads, formerly in service with the US and British navies. |
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ELIZABETH KNOWLES. "Polaris." The Oxford Dictionary of Phrase and Fable. 2006. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. ELIZABETH KNOWLES. "Polaris." The Oxford Dictionary of Phrase and Fable. 2006. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1O214-Polaris.html ELIZABETH KNOWLES. "Polaris." The Oxford Dictionary of Phrase and Fable. 2006. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O214-Polaris.html |
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Polaris
Polaris See Pole Star
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"Polaris." World Encyclopedia. 2005. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. "Polaris." World Encyclopedia. 2005. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1O142-Polaris.html "Polaris." World Encyclopedia. 2005. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-Polaris.html |
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Polaris
Polaris •arris, Clarice, Harries, Harris, Paris
•mattress • actress • benefactress
•Polaris • enchantress
•derris, Nerys, terrace
•Emrys • empress
•directress, Electress
•temptress • sempstress
•Apollinaris, heiress
•waitress • seamstress • ex libris
•headmistress, mistress
•housemistress • toastmistress
•schoolmistress • ancestress
•dentifrice
•iris, Osiris
•tigress, Tigris
•cypress
•Boris, doch-an-dorris, Doris, Horace, Maurice, Norris, orris
•cantoris, Dolores, loris
•laundress • fortress • jointress
•hubris • buttress
•conductress, instructress, seductress
•huntress • peeress • Beatrice
•arbitress • berberis • anchoress
•ephemeris • ambassadress
•adventuress • clitoris • authoress
•avarice
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"Polaris." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. "Polaris." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1O233-Polaris.html "Polaris." Oxford Dictionary of Rhymes. 2007. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O233-Polaris.html |
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