Polaris designated α Ursae Minoris, commonly the North Star or Pole Star, is the brightest star in the constellation of Ursa Minor. It is very close to the north celestial pole, making it the current northern pole star. The revised Hipparcos parallax gives a distance to Polaris of about 433 light-years (133 parsecs). Polaris is a triple star system, composed of the primary star, Polaris Aa (a yellow supergiant), in orbit with a smaller companion (Polaris Ab); the pair in orbit with Polaris B (discovered in August 1779 by William Herschel). The reason Polaris is so important is because the axis of Earth is pointed almost directly at it. During the course of the night, Polaris does not rise or set, but remains in very nearly the same spot above the northern horizon year-round while the other stars circle around it. So at any hour of the night, at any time of the year in the Northern Hemisphere, you can readily find Polaris and it is always found in a due northerly direction. If you were at the North Pole, the North Star would be directly overhead.