Triton, the largest moon of Neptune

Triton, the largest moon of Neptune

Fig. 11.14 . A mosaic of the south polar cap of Triton, the largest satellite of Neptune, taken in August 1989 from the Voyager 2 spacecraft. At the time of this flyby, Triton was the coldest measured object in the solar system with a surface temperate of 38 kelvin. It is so cold that most of Tritonís thin nitrogen atmosphere is condensed as frost, making it the only satellite in the solar system known to have a surface coated with deposits of solid nitrogen ice. Small admixtures of highly reflective methane ice are also present on the surface; they have been reddened and darkened by the action of energetic radiation. Dark plumes and streaks probably mark vents of ice volcanoes, where nitrogen gas has been driven outward in geyser-like eruptions from beneath the surface and carried by the winds into elongated streaks. (Courtesy of NASA/JPL.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University