HIGH-TEMPERATURE HOT SPOTS ON IO AS SEEN BY THE GALILOE SOLID-STATE IMAGING (SSI) EXPERIMENT

High-temperature hot spots on Io have been imaged at similar to 50 km spatial resolution by Garileo's CCD imaging system (SSI). Images were acquired during eclipses (Io in Jupiter's shadow) via the SSI clear fi lter (similar to 0.4-1.0 mu m), detecting emissions from both small in tense hot spots and diffuse extended glows associated with Io's atmosp here and plumes. A total of 13 hot spots have been detected over simil ar to 70% of Io's surface. Each hot spot falls precisely on a low-albe do feature corresponding to a caldera floor and/or lava flow. The hot- spot temperatures must exceed similar to 700 K for detection by SSI. O bservations at wavelengths longer than those available to SSI require that most of these hot spots actually have significantly higher temper atures (similar to 1000 K or higher) and cover small areas. The high-t emperature hot spots probably mark the locations of active silicate vo lcanism, supporting suggestions that the eruption and near-surface mov ement of silicate magma drives the heat flow and volcanic activity of Io.