This color picture of Ganymede, Jupiter's largest satellite, was taken on the afternoon of March 2, 1979, by Voyager 1 from a distance of about 3.4 million kilometers (2.1 million miles).  This photograph was assembled from three black-and-white pictures in the Image Processing Laboratory at JPL.  This face of Ganymede is centered on the 260 deg.  meridian.  Ganymede is slightly larger than the planet Mercury but has a density alm deg.st three times less than Mercury.  Theref deg.re, Ganymede pr deg.bably c deg.nsists in large part  deg.f ice.  At this res deg.luti deg.n the surface sh deg.ws light and dark markings interspersed with bright sp deg.ts.  The large darkish area near the center  deg.f the satellite is cr deg.ssed by irregular light streaks s deg.mewhat similar t deg. rays seen  deg.n the M deg. deg.n.  The bright patch in the s deg.uthern hemisphere is reminiscent  deg.f s deg.me  deg.f the larger rayed craters  deg.n the M deg. deg.n caused by mete deg.rite impacts.   JPL manages and c deg.ntr deg.ls the V deg.yager pr deg.ject f deg.r NASA's  deg.ffice  deg.f Space Science.