English, Van H. Department of Geography, Dartmouth College, Hanover, New Hampshire.
Last reviewed:December 2019
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That end of the Earth's axis which points toward the North Star, Polaris (Alpha Ursae Minoris). It is the geographical pole located at 90° N latitude where all meridians converge and should not be confused with the north magnetic pole, which is in the Canadian Archipelago. The North Pole's location falls near the center of the Arctic Sea. Being at the end of the Earth's axis, which is inclined 23 1/2° (23°.45) from a line perpendicular to the plane of the ecliptic, the North Pole has phenomena unlike any other place except the South Pole. For 6 months the Sun does not appear above the horizon and for 6 months it does not go below the horizon. During this latter period, March 21–September 23, the Sun makes a very gradual spiral around the horizon, gaining altitude until June 21; then it starts to lose altitude until it disappears below the horizon after September 23. The Sun's highest altitude is 23 1/2°. As there is a long period (about 7 weeks) of continuous twilight before March 21 and after September 23, the period of light is considerably longer than the period of darkness.
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