Taken in 1989 by Voyager 2 during its flyby of the Neptune system, this is a global colour mosaic of Triton. With a radius about 22 percent smaller than Earth's moon, Triton is the largest satellite of Neptune and is one of the few bodies in the solar system known to have a nitrogen-dominated atmosphere. The others are Earth and Saturn's giant moon, Titan. Triton is so cold that most of its nitrogen is condensed as frost, making it the only satellite in the solar system known to have a surface made mainly of nitrogen ice. Image Credit: NASA/JPL/USGS. Choose to buy this photograph as an unframed print, a mounted box canvas print, or a framed print.