Circumpolar stars

Explanation

The circumpolar stars appear to lie within a circle that is centered at the celestial pole and tangential to the horizon. At the Earth's North Pole, the north celestial pole is directly overhead, and all stars that are visible at all (that is, all stars in the Northern Celestial Hemisphere) are circumpolar. As one travels south, the north celestial pole moves towards the northern horizon. More and more stars that are at a distance from it begin to disappear below the horizon for some portion of their daily "orbit", and the circle containing the remaining circumpolar stars becomes increasingly small. At the Equator, this circle vanishes to a single point – the celestial pole itself – which lies on the horizon, and so all of the stars capable of being circumpolar are for half of every 24 hour period below the horizon. There, the pole star itself will only be made out from a place of sufficient height.