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Such a definition implies that different stars can be defined as circumpolar at different Earth latitudes. For example, to an observer place right at the Earth's North or South Pole, virtually all the stars are circumpolars. For an observer exactly on the equator, no star can be defined circumpolar, as the pole itself is on the horizon. At different latitudes, an intermediate situation makes some stars circumpolars and others not.
On the northern hemisphere all circumpolar stars rotate around the North Star Polaris, which iself it almost stationary, always at the north (i.e., the azimuth is 0°), and always at the same altitude (angle from the horizon), equal to the latitudeLatitude denoted φ, gives the location of a place on Earth north or south of the Equator. Latitude is an angular measurement ranging from 0° at the Equator to 90° at the poles. Usually, the difference in latitude largely affects the climate and/or wea of the point of observation on Earth.