Polaris

• Polaris, also known as the Pole Star and the North Star, is located at True North and is stationary throughout the Year.
• Its name in Latin was ‘Stella Maris’ (Sea Star) because of its importance to sailors in Celestial Navigation.

Finding the Pole Star

• The Pole Star is the brightest star in the Ursa Minor constellation.
• An axis line from the south pole to the north pole passes straight through the pole star to within one degree.
• Therefore the Pole Star appears never to move.
• In the Northern Hemisphere, the celestial sphere containing all the stars and planets appears to revolve anticlockwise around the pole star.

Celestial Navigation

• Polaris was known as ‘Stella Maris’ because of its importance to sailors:

• True North:
  • The Pole star is positioned within one degree of True North and is stationary, therefore it is easy to use for orientation in Celestial Navigation.

• Latitude:
  • Because the Pole Star can be seen in the night sky in the Northern Hemisphere at all times, it can be used to calculate Latitude.
  • If the angle between the observer and the Pole Star is 51 degrees above the Horizon, then the observer is at Latitude 51 degrees North.