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High-resolution view of Io’s Pele volcano glowing in the dark

In a high-resolution view from NASA’s Galileo spacecraft, the Pele
hot spot on Jupiter’s moon Io shows a complex pattern of areas glowing in
the dark, including areas likely to be fresh overturning of a lava lake’s

Hundreds of hot spots have been observed on Io, the most volcanic world in
the solar system. Most previous observations have been at very low resolution. This false-color nighttime image of the Pele hot spot, acquired during
Galileo‘s close flyby of Io in October 2001, reveals details down to 60
meters (200 feet) in length. Red indicates the most intense combination of
temperature and area; blue indicates cooler materials or smaller patches of
hot materials.

Scientists believe the Pele hot spot has a lava lake inside a volcanic
crater or caldera. The series of bright spots seen here may correspond to
the edge of the caldera, where cooled crust of the lava lake is breaking up
against the wall and hotter lava appears from underneath. (That pattern is
seen in a lava lake in Hawaii). Alternatively, they could be fractures in
the lava lake’s crust. Galileo acquired similar observations in
October 1999 and February 2000, but the newest images are the
first to show the larger bright areas seen on the right side of the image.
These probably correspond to regions of vigorous overturning of the crust.

Galileo acquired several nighttime images of Pele in October 2001. These
may enable measurements of temperature and perhaps detection of short-term
changes in the exposures of hot lava. Preliminary calculations indicate the
lava temperature is about 1,400 Kelvins (2,060 degrees Fahrenheit) at one
location, which would be similar to the temperatures of lava erupted at
Kilauea in Hawaii.

North is the top of the picture. The image is centered at 18.7 degrees
south latitude and 255.5 degrees west longitude. Galileo‘s camera took it
from a distance of about 6,000 kilometers (3,700 miles) away.

Image produced by: Paul Geissler
Planetary Image Research Lab. (PIRL)
, Lunar and Planetary Lab. (LPL),
University of Arizona

The Jet Propulsion Laboratory, a division of the California Institute of
Technology in Pasadena, manages the Galileo mission for NASA’s
Office of Space Science, Washington, D.C. Additional information about
Galileo and its discoveries is available on the Galileo mission
home page at
Background information and educational context for the images can be found at

NASA’s Planetary Photojournal PIA-02596