From http://galileo.jpl.nasa.gov/images/iotrajectory.html

                            Image Title: Io Trajectory of
                                         Galileo Spacecraft


                               Released: October 7, 1999
                                Mission: Galileo


                          Click on image to see a larger version.

Original Caption Released with Image:
NASA's Galileo spacecraft will encounter Jupiter's volcanic
moon Io on its 24th and 25th orbits. The ground tracks for
these flybys of Io are labeled I24 and I25 in this color image
of Io, taken in 1996 by Galileo.

The Io flybys are scheduled for October 10, 1999 and November
25, 1999. Each large "X" marks the position of closest approach
for a flyby, and the tic marks along each groundtrack show the
position of the spacecraft in two-minute intervals before and
after closest approach. The arrow next to the closest approach,
labeled I25, indicates that this encounter occurs behind the
limb of Io as it is seen in this image. The image shows
approximately the hemisphere of Io that will be illuminated
during the flybys (although the volcano Pele, shown here on the
left limb, will actually be on the night side). Several of the
active volcanic centers to be observed at close range are
labeled. The blue background is Jupiter's atmosphere as seen
through violet, green, and near-infrared filters.

North is to the top of the picture and the Sun illuminates the
surface from almost directly behind the spacecraft. The image
is centered at 0 degrees north latitude and 175 degrees west
longitude. The resolution is 5 kilometers (3.1 miles) per
picture element. The image was taken on September 7, 1996 at a
range of about 487,000 kilometers (about 302,000 miles) by the
camera onboard Galileo.