Brightly glowing lava from the volcano Pele is seen in this image taken by NASA's Galileo spacecraft as it receded from its close flyby of Jupiter's moon Io in October, 1999. The image at left shows Io's surface in approximately true color, centered on the large red ring of sulfur that was deposited by Pele's plume and reaches more than 1,300 kilometers (808 miles) in diameter. A false color infrared composite of the same region is shown on the right. The dark red dot at the center of the ring (seen in the false color picture) is the glow of hot lava at the heart of the volcano. Temperatures up to 1,027 degrees celsius (1,880 degrees fahrenheit) have been previously measured for Pele's lava. The glow is bright enough to be imaged in daylight, allowing scientists to precisely pinpoint the eruptive center.
The region imaged is centered on 18 degrees south, 255 degrees west, and is almost 2,000 kilometers (1,243 miles) across. North is toward the top right of the picture and the sun illuminates the surface from the west.