Polaris (α Ursae Minoris, α UMi, commonly North Star or Pole Star) is the brightest star in the constellation Ursa Minor, and the 45th brightest star in the night sky. It is very close to the north celestial pole, making it the current northern pole star.
It is a multiple star, comprising the main star, α UMi Aa, which is a supergiant; two smaller companions, α UMi B and α UMi Ab; and two distant components, α UMi C and α UMi D. α UMi B was discovered in 1780 by William Herschel.
The revised Hipparcos parallax calculates the distance to Polaris at about 434 light-years (133 parsecs). Many recent papers derive distances up to 30% closer, particularly if the fundamental pulsation mode is assumed