Eye on Ganymede

Photojournal: PIA02837

December 16, 2004

Jupiter casts a baleful eye toward the moon Ganymede in this
enhanced-contrast image from NASA's Cassini spacecraft.

Jupiter's 'eye', the Great Red Spot, was captured just before disappearing
around the eastern edge of the planet. The furrowed eyebrow above and to
the left of the spot is a turbulent wake region caused by westward flow
that has been deflected to the north and around the Red Spot. The smallest
features visible are about 240 kilometers (150 miles) across.

Within the band south of the Red Spot are a trio of white ovals, high
pressure counterclockwise-rotating regions that are dynamically similar to
the Red Spot. The dark filamentary features interspersed between white
ovals are probably cyclonic circulations and, unlike the ovals, are
rotating clockwise.

Jupiter's equatorial zone stretching across the planet north of the Spot
appears bright white, with gigantic plume clouds spreading out from the
equator both to the northeast and to the southeast in a chevron pattern.
This zone looks distinctly different than it did during the Voyager flyby
21 years ago. Then, its color was predominantly brown and the only white
plumes conspicuous against the darker material beneath them were oriented

Ganymede is Jupiter's largest moon, about 50 percent larger than our own
Moon and larger than the planet Mercury. The visible details in this image
are different geological terrains. Dark areas tend to be older and heavily
cratered; brighter areas are younger and less cratered. Cassini images of
Ganymede and Jupiter's other large moons taken near closest approach on
Dec. 30 will have resolutions about four times better than that seen here.

This image is a color composite of ones taken with different filters by
Cassini's narrow-angle camera on Nov. 18, 2000, processed to enhance
contrast. Cassini is a cooperative project of NASA, the European Space
Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a
division of the California Institute of Technology in Pasadena, manages
the Cassini mission for NASA's Office of Space Science, Washington, D.C.

Credit: NASA/JPL/University of Arizona


For higher resolution, click here.