Polaris

6.18 - Be able to find the latitude of an observer using Polaris

Polaris is located at very close to 90° in the sky. This is the Northern Celestial Pole. If you stood at the North Pole and looked up, it would be directly above your head. Because of this we can find our latitude in the Northern Hemisphere by measuring the angle of Polaris in the sky.

Polaris is doubly useful as it appears fixed in the sky and other stars seem to rotate aound it. It always points north.

It lies less than 1° to the North Celestial Pole. This is often abbreviated to NCP. An easy way to find an observers latitude is to measure the angle of Polaris.

Altitude of NCP = Latitude of Observer

If you were slightly north of the Equator you may be able to see Polaris on the horizon looking north.

From London you can see Polaris at approx 51° north.

There is no bright star that represents the Southern Celestial Pole.

In Time...

Polaris is the North Star - at the moment! It is a coincidence that we have a fairly bright star above one of our poles. In time the point of north will drift away from where Polaris will be. This is due to precession which happens because Earth has a slight wobble.

 

Questions

At what angle in the sky would polaris be from London (51° north)?

Animation
Did you know?

Some people think Polaris is the brightest star in the sky. This is incorrect, the brightest star is Sirius.

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