The planet Neptune as seen by Voyager 2 in August 1989. (Courtesy NASA/JPL).
Two 591-second long exposures were needed to capture this view of Neptune's rings. These pictures were taken by Voyager 2, the only spacecraft ever to visit this distant planet, on August 29, 1989. (Courtesy NASA/JPL)
About three days after its spectacular encounter with Neptune, Voyager 2 looked back and captured this parting shot of Neptune and its larger moon, Triton. (Courtesy NASA/JPL).
Color enhanced view of Triton's southern hemisphere. The bright region at the bottom is the South Polar Cap. The blue-ish region near the terminator (dark) is near the equator. Some of the dark streaks on the polar cap may be deposits of material erupted from geysers or volcanoes that were discovered on this strange moon. (Courtesy NASA/JPL).