Pole star

A pole star or polar star is a star, preferably bright, nearly aligned with the axis of a rotating astronomical body.

A 45-minute exposure photo of stars around Polaris, taken at Ehrenburg (Franconia, Germany), September 8, 2001

Currently, Earth's pole stars are Polaris (Alpha Ursae Minoris), a bright magnitude 2 star aligned approximately with its northern axis that serves as a pre-eminent star in celestial navigation, and a much dimmer magnitude 5.5 star on its southern axis, Polaris Australis (Sigma Octantis).

From around 1700 BC until just after 300 AD, Kochab (Beta Ursae Minoris) and Pherkad (Gamma Ursae Minoris) were twin northern pole stars, though neither was as close to the pole as Polaris is now.

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