12 October 1984
Vol 226, Issue 4671

About The Cover

Io, one of Jupiter's moons. Color, shown in mosaic of images acquired by Voyager 1 in 1979, is not the natural sulfurous yellow of Io but has been computer-enhanced to show the wide range of colored units on the satellite's surface. The region shown is one of the most active volcanic regions on Io. The dark semicircular feature with a bright region within it is the Loki Patera, believed to be a lava lake more than 200 kilometers in diameter and possibly filled with molten sulfur. See page 134. [Computer processing and color enhancement by A. McEwen and L. A. Soderblom, Astrogeology Branch, U.S. Geological Survey, Flagstaff, Arizona; photo courtesy of Jet Propulsion Laboratory/NASA and U.S. Geological Survey]