Principle of operation of an equatorial mount to keep a telescope pointing in the same direction. The black spots denote rotation axes seen end-on. The green telescope is rotated at the same rate as the earth but in the opposite direction, while the red telescope is not driven.
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<ul><li><a href="//commons.wikimedia.org/wiki/File:North_pole_february_ice-pack_1978-2002.png" title="File:North pole february ice-pack 1978-2002.png">North_pole_february_ice-pack_1978-2002.png</a></li></ul>