Circumpolar Stars
18 Dec 2008, 05:38 UTC
Circumpolar stars are those stars that are nearest the north star Polaris. These stars are in a special category because they are always visible every night and rather than rise in the east and set in the west like most of the stars in the sky (and the moon and planets), instead they circumscribe Polaris every 24 hours, hence the designation circumpolar.From our latitude in San Francisco, 38 degrees north of the equator, we see Polaris 38 degrees up above the horizon due north. Although it is a celebrated star because of its unique location, Polaris is not the brightest star in the sky - that honor goes to Sirius in Canis Major. However, being at the point in the sky where Earth's north pole projects into space means that Polaris does not move over the course of a day or even over the course of a year, a truly unique star!The "circumpolar region" of the sky is a circle that stretches from Polaris 38 degrees down to the horizon and 38 degrees in every other direction around it. Everything that you can see in this zone remain above the horizon every night. All the stars and constellations move in ...