English: Each time NASA's Galileo spacecraft orbits the planet Jupiter, it encounters one of the four Galilean satellites. From left to right in this mosaic, the moons shown are Io, Europa, Ganymede, and Callisto. Throughout the eleven orbits in Galileo's nominal mission the Solid State Imaging (CCD) system builds up views of the satellite surfaces in different colors and at varying spatial resolutions.

The top row displays the correct relative sizes of the satellites in global views. In these relatively low resolution images the smallest features that can be seen are about 20 kilometers in size. These views show how the surfaces have been affected on the largest scales by either tectonic or volcanic changes in the interiors of the moons or by deposition from the exterior environment. In the middle row the picture resolutions are up to ten times higher and are suitable for investigations of the dominant regional features that are seen, such as fields of volcanic caulderas on Io (the black spots), tidally induced cracks thousands of kilometers long on Europa, bright grooved regions on Ganymede's extended surface, and enormous impact basins on Callisto due to hypervelocity impacts with primitive comets or asteroids. The bottom row displays views typical of the highest resolutions that have been achieved (up to about 20 meters) and which are used to study the nature and physical origins of individual structures on the surface, such as the individual vents from which volcanic plumes originate on Io, the ridges that are everywhere on Europa, the fractured and pulled apart grooved terrain on Ganymede, or the heavily eroded and mantled craters on Callisto.

Captions translated in French.