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These two pictures show the South Pole of Triton. The polar ice cap is the light pink area along the bottom of the lower picture.
Click on image for full size
Images courtesy of NASA/JPL/USGS.

The Poles of Triton

Triton is the largest moon of Neptune. It is a very unusual moon. The poles of Triton are especially interesting.

Triton has a polar ice cap at the South Pole. Earth, of course, has ice caps at its poles too. On Earth the ice caps are frozen water. On Triton, the ice caps are made of frozen nitrogen (and maybe some methane). Nitrogen is the main gas in Earth's atmosphere, but on Triton it is so cold that nitrogen freezes. The temperature on Triton is around -235° C (-391° F)! Scientists think Triton has an ice cap at its North Pole, too. However, we don't have any pictures of its North Pole yet.

Scientists have spotted ice volcanoes near the South Pole of Triton. There are only three other places in the Solar System that have volcanoes or geysers. Earth is one, Jupiter's moon Io is the second, and Saturn's moon Enceladus is the third.

Triton has a strange orbit around Neptune. Because of that, most of the time one of Triton's poles is tilted towards the Sun. Neptune takes more than 160 years to orbit the Sun once. That means that Triton's poles spend about 80 years in darkness followed by 80 years of sunlight. The seasons at Triton's poles last for decades!

Last modified April 21, 2009 by Randy Russell.

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