19 October 1990
Vol 250, Issue 4979

About The Cover

Montage of Voyager 2 images showing surface activity on Triton, Neptune's large satellite. Upper left: Triton's south polar region with dark streaks from extinct geysers. Upper right: Enhanced image of the remainder of the polar region. Lower left: Image of “east” plume, which was erupting from Triton's surface at the time of the Voyager 2 encounter, with both the plume (dark blue streak in left of center) and fine particles (probably nitrogen ice crystals) suspended in the atmosphere above the limb shown in deep blue. Lower right: Two different Voyager 2 images of the active “west” plume, projected to a common viewpoint and composited in red and blue. Parallax between the two images causes the plume and its cloud trail to appear as a horizontal red-blue streak. See page 410 to 443. [Photographs courtesy of National Aeronautics and Space Administration and the U.S. Geological Survey]