The North Star, also known as Polaris, is famous for holding nearly still in our sky while the entire northern sky revolves around it. Because it is located nearly at the north celestial pole, it has been an invaluable tool for navigation in the Northern Hemisphere for centuries.

Location and Constellation

Polaris is the brightest star in the constellation Ursa Minor, often called the Little Dipper. It sits at the very end of the 'handle' of the Little Dipper.

Finding Polaris

You can easily locate Polaris by first finding the Big Dipper (part of the Ursa Major constellation). The two stars at the end of the Big Dipper's 'bowl' (Dubhe and Merak) are known as the "Pointers." Drawing an imaginary line through these two stars and extending it will lead you directly to Polaris.

The method for finding the star can be seen in this diagram.

Importance for Navigation

Because Polaris is situated almost directly above the Earth's North Pole, it appears stationary in the sky. All other stars appear to rotate counter-clockwise around it over the course of a night. This makes its altitude (angle above the horizon) a close approximation of the observer's latitude.

Historical Context

Historically, sailors and explorers would determine their latitude by measuring the angle between Polaris and the horizon using an instrument called a sextant. The constancy of the North Star has made it a reliable celestial compass for navigating the northern seas and continents for millennia.

Physical Characteristics

While Polaris appears as a single bright star to the naked eye, it is actually a multiple-star system. The main star, Polaris A, is a massive supergiant star.

Although Polaris is the current North Star, the Earth's axis slowly precesses (wobbles) over a 26,000-year cycle. In about 12,000 years, the star Vega will be the North Star.