<P> 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 there are thus effectively no circumpolar stars at all . </P> <P> As one travels south of the Equator, the opposite happens . The south celestial pole appears increasingly high in the sky, and all the stars lying within an increasingly large circle centered on that pole become circumpolar about it . This continues until one reaches the Earth's South Pole where, once again, all visible stars are circumpolar . </P> <P> The north celestial pole is located very close to the pole star (Polaris or North Star), so from the Northern Hemisphere, all circumpolar stars appear to move around Polaris . Polaris itself remains almost stationary, always at the north (i.e. azimuth of 0 °), and always at the same altitude (angle from the horizon), equal to the observer's latitude . These are then classified into quadrants . </P> <P> Whether a star is circumpolar depends upon the observer's latitude . Since the altitude of the north or south celestial pole (whichever is visible) equals the absolute value of the observer's latitude, any star whose angular distance from the visible celestial pole is less than the absolute latitude will be circumpolar . For example, if the observer's latitude is 50 ° N, any star will be circumpolar if it is less than 50 ° from the north celestial pole . If the observer's latitude is 35 ° S, then all stars within 35 ° of the south celestial pole are circumpolar . Stars on the celestial equator are not circumpolar when observed from any latitude in either hemisphere of the Earth . "A star with its polar distance approximately equal to or less than the latitude of the observer". </P>

8. explain how it is that some stars never rise in our sky and others never set