Editing Celestial pole (section)

==Finding the north celestial pole==
{{See also|Pole star|Polar alignment}}

[[File:Star Trails Shoreline.jpg|left|thumb|Over the course of an evening in the [[Northern Hemisphere]], [[circumpolar star]]s appear to circle around the north celestial pole. [[Polaris]] (within 1° of the pole) is the nearly stationary bright star just to the right of center in this [[star trail]] photo.]]

The north celestial pole currently is within one degree of the bright star [[Polaris]] (named from the [[Latin]] ''stella polaris'', meaning "[[pole star]]"). This makes Polaris, colloquially known as the "North Star", useful for navigation in the [[Northern Hemisphere]]: not only is it always above the north point of the horizon, but its [[altitude|altitude angle]] is always (nearly) equal to the observer's geographic [[latitude]] (though it can, of course, only be seen from locations in the Northern Hemisphere).

Polaris is near the north celestial pole for only a small fraction of the 25,700-year precession cycle. It will remain a good approximation for about 1,000 years, by which time the pole will have moved closer to Alrai ([[Gamma Cephei]]). In about 5,500 years, the pole will have moved near the position of the star [[Alderamin]] (Alpha Cephei), and in 12,000 years, [[Vega]] (Alpha Lyrae) will become the "North Star", though it will be about six degrees from the true north celestial pole.

To find Polaris, from a point in the Northern Hemisphere, face north and locate the [[Big Dipper]] (Plough) and [[Little Dipper]] asterisms. Looking at the "cup" part of the Big Dipper, imagine that the two stars at the outside edge of the cup form a line pointing upward out of the cup. This line points directly at the star at the tip of the Little Dipper's handle. That star is Polaris, the North Star.<ref>{{cite web|author=Loyola University Chicago|title=Earth-Sky Relationships and the Celestial Sphere|url=http://www.luc.edu/faculty/dslavsk/courses/phys478/classnotes/celestial-sphere.pdf |archive-url=https://web.archive.org/web/20140110122603/http://www.luc.edu/faculty/dslavsk/courses/phys478/classnotes/celestial-sphere.pdf |archive-date=2014-01-10 |url-status=live|access-date= 10 March 2014}}</ref>