Io with Loki Plume on Bright Limb

NASA's Voyager 1 image of Io showing active plume of Loki on limb. Heart-shaped feature southeast of Loki consists of fallout deposits from active plume Pele. The images that make up this mosaic were taken from an average distance of approximately 490,000 kilometers (340,000 miles).

http://photojournal.jpl.nasa.gov/catalog/PIA00010