Polaris/The North Star

Polaris : The North Star

To navigate on the surface of the earth men have traditionally turned to the stars for guidance . The titular North Star at this point in history is called Polaris but the north star is not static . It is called Polaris from its Latin name , Stella Polaris . In recorded history there have been other stars that have been navigational beacons in the northern hemisphere . To serve in that capacity a star must be visible obviously and it must be circumpolar to the North Pole . This means that it must

be near the North Pole and it must never dip below the horizon staying visible throughout the night . Certainly a star that sets at times and is no longer visible to the navigator would be of limited use Polaris can be found in the northern hemisphere by its position as the end of the handle of the Little Dipper , the constellation Ursa Minor . To readily locate Polaris a person can locate the Big Dipper , Ursa Major and follow the two stars at the end of the cup upward . That line will lead the eye directly to the North Star it is the last and brightest star in the tail of the Little Dipper (Pasachoff et al . 2000

13 Though Polaris is called the North Star and is used as a north star for the purpose of navigation , it does not actually hold a perfect polar position . It is off by two thirds of 1 degree (275 . Though Polaris is yielding scientific data that may prove of great import , it is Polaris role in man 's exploration of this planet that gives it the position of imminence that it holds . Polaris can only give the observer information concerning his position in regard to latitude , but this is still good enough for seamen to circumnavigate the globe

Polaris appears to be virtually motionless in the night sky because it lies on an almost direct line along the earth 's imaginary axis and all the other visible stars in the sky appear to rotate around it as the night passes . What , with the naked eye appears to be one star , is in fact a trinary system , which means it consists of not one but three separate stars in a tight orbit . The primary star is a large yellow Cepheid variable , orbited by a bright yellow dwarf , similar to the Sun at a distance of 360 billion kilometers and a third dwarf star companion , orbiting at only 2 .8 billion kilometers . The yellow dwarf in the further orbit is visible with a low power telescope and has been known for over two hundred years . The dwarf in tight orbit is so close to its much brighter giant companion star is not visible . It was detected in 1929 by spectrum analysis and then finally was photographed by the Hubble telescope in January of 2006 . Polaris is 431 light years from Earth , according to astrometric measurements of the Hipparcos satellite . It is classed...