The North Star: Polaris Facts

Find facts about Polaris such as where to locate it, what its nicknames are, and how its title as the North Star is only temporary.

The North Star, Polaris, gets its name from being the Pole Star. The North Pole of the Earth, about which the planet spins, points directly at this star. Therefore, while the Earth spins and the stars appear to circle about the Earth, Polaris remains in the same place. This constancy of the North Star was very important for early travelers, giving them a nighttime target to help guide themselves.

The Many Names for Polaris

Polaris goes by many names, including the Pole Star, the North Star, the Lodestar, and Alpha Ursae Minoris, among others. Polaris is the brightest star in the constellation of Ursa Minor, the Lesser Bear, also known as the Little Dipper.

The Little Dipper is best seen away from light-polluted skies. The common trick for finding Polaris and its constellation is to use the easily visible Big Dipper as guide stars. In the bowl of the Big Dipper, the last two stars farthest from the handle can be used to draw a line and point to Polaris. Polaris is easy to spot because it is the only star of moderate brightness in its area.

Polaris shines at magnitude 1.97 and lies 430 light-years away. Polaris is a multiple star system with one giant star, two smaller companions, and two distant companions. But for the most part, the main components are referred to as Polaris A and Polaris B and can be separated in a telescope.

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Polaris Won’t Always Be the Pole Star

As the Earth spins on its axis, it also wobbles a bit, just as a top does. This wobble is called precession, and precession causes the North and South Poles to change where they are pointing. Currently, the North Pole points at Polaris, but it didn’t always and it won’t in the future.

The precession of the equinoxes is the name given to the phenomenon of the North Pole cycling through this wobble once every 26,000 years. It is only by chance that the North Pole points to within one degree of Polaris at this moment. A few thousand years ago the “Pole Star” was Thuban in Draco. About 14,000 years from now, the “Pole Star” will be Vega in Lyra. For much of the time in between, the North Pole will point to no exact star at all, just a dark region of the sky.

Polaris in Astrophotography

Polaris is a very useful target for astrophotographers hoping to capture long-exposure star-trail photos. Astrophotographers aim their cameras at Polaris and leave the shutter open for varying lengths of time, from a few minutes to all night, as the stars slowly circle the center of their image, creating the well-known star trail photo like the one seen here.

Source: Celestron’s The Sky Software

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