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August 27, 1999: Jupiter's exotic moon Io is often likened
to a pepperoni pizza. Its mozzarella-colored surface is pockmarked
by ruddy volcanic plumes that evoke images of sliced Italian
sausage among imaginative scientists. The strange appearance
of Io's surface is constantly changing as it is formed and reformed
by lava flows of molten silicate rock. What drives this volcanic
powerhouse? The most likely energy source is changing gravitational
tides caused by nearby Jupiter. Above: This false color image shows
small-scale features which were not recognized previously and
which suggest that the lava and sulfurous deposits on Io are
composed of complex mixtures (close-up A). Some of the bright,
whitish, high-latitude (near the top and bottom) deposits have
an ethereal quality like a transparent covering of frost (close-up
B). Bright red areas were seen in previous images only as diffuse
deposits. However, they now appear as both diffuse deposits and
sharp linear features like fissures (close-up C). Some volcanic
centers have bright and colorful flows, perhaps due to flows
of sulfur (rather than silicate) lava (close-up D). In this region
of Io, bright, white material can also be seen to emanate from
linear rifts and cliffs. |
Web Links | |
Ice, Water and Fire the Galileo Europa Mission Galileo home page at JPL, with the latest on Europa, Callisto and Io Jet Propulsion Laboratory home page Io from the SEDS Nine Planets web site Callisto from the SEDS Nine Planets web site Jupiter from the SEDS Nine Planets web site Io: The Prometheus Plume Aug. 18, 1997 Astronomy Picture of the Day Close-up of an Io volcano Aug. 4, 1995 Astronomy Picture of the Day Sizzling Io July 6, 1998 Astronomy Picture of the Day Related Stories: |
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