Polaris

-Recall the declination of Polaris (+90 degrees) and explain why Polaris appears fixed in the night sky
-Demonstrate an understanding that the elevation of Polaris above the northern horizon is equal to the latitude of the observer

Polaris is located at very close to 90 degrees 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.

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 degrees 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 degrees north)?

Animation
Mythbuster

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

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