FOR RELEASE:  October 4, 1996

RELEASE NO.:  STScI-PRC96-30



              RARE HUBBLE PORTRAIT OF IO AND JUPITER

This image, shows Jupiter's volcanic moon Io passing above the
turbulent clouds of the giant planet, on July 24, 1996.  The
conspicuous black spot on Jupiter is Io's shadow.  The shadow is
about the size of Io (3,640 kilometers or 2,262 miles across) and
sweeps across the face of Jupiter at 17 kilometers per second
(38,000 miles per hour).

The smallest details visible on Io and Jupiter are about 100
miles across.  Bright patches visible on Io are regions of sulfur
dioxide frost.  Io is roughly the size of Earth's moon, but 2,000
times farther away.

This is one of a series of images of Io taken by Hubble to
complement the close-up images currently being taken by the
Galileo spacecraft now orbiting Jupiter.  Though the Galileo
images show much finer detail, Hubble provides complementary
information because it can observe Io at ultraviolet wavelengths
not seen by Galileo, can observe Io at different times than
Galileo, and can view Io under more consistent viewing
conditions.

The image was taken at violet wavelengths, with the Wide Field
Planetary Camera 2, in PC mode. 

CREDIT: J. Spencer (Lowell Observatory), and NASA

Image files in GIF and JPEG format and captions may be accessed
on Internet via anonymous ftp from oposite.stsci.edu in
/pubinfo:
                         GIF            JPEG
PRC96-30  Jupiter and Io      gif/iotrans.gif         
jpeg/iotrans.jpg

A higher resolution digital version (300 dpi JPEG) of the release
photograph is available in /pubinfo/hrtemp: 96-30.jpg.

GIF and JPEG images, captions and press release text are
available via World Wide Web at
http://www.stsci.edu/pubinfo/PR/96/30.html and via links in:
http://www.stsci.edu/pubinfo/Latest.html or 
http://www.stsci.edu/pubinfo/Pictures.html.