POLARIS, ACTUAL POLE STAR

Polaris is the actual pole star , indeed it wasn't always this star that indicated the north. Before it was Kochab which belong to the small bear too. Polaris is a double star with a variable magnitude. It weight is 8 times that of the sun. The visual magnitude of alpha Polaris is approximately 2,0 whereas the one of the sun is -26,7. But that's from the earth because in the space the polar shines 1600 times more than the sun (absolute magnitude). It surface temperature is 6300 K. It is almost on the earth axis of rotation : at less than 1. This one approach the pole more each year. It will pass at less than 1/2 from the north pole in 2105.

photography realised by Cémilia Deschamps, Anne Girard et Sonia Germain.

How to locate Polaris...

We know that the earth realize one round on itself in 24 hours and we know too that this same movement is observed in one year for a same hour. We can observe this movement on the photography, the pole star is the bright star near the rotation axis of others stars.

We can locate the Pole Star with the Big Bear : on this constellation, we take the distance between beta and tau Ursa Majoris ( blue line ) since we prolong five times.

At last, we arrive at Pole Star.

 

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