16 Encyclopedia of the Solar System
FIGURE 7 A sampling of satellites in the solar system:
the dusty surface of the Earth’s Moon, still the only
other celestial body visited by humans (top row, left);
Phobos, the larger of Mars’ two moons showing the
large crater Stickney at left (top row, right); the
innermost Galilean satellite, Io, displays active
vulcanism on its sulfur-rich surface (second row, left);
the outermost Galilean satellite, Callisto, displays a
heavily cratered surface, likely dating back to the origin
of the solar system (second row, right); one of Saturn’s
smaller satellites, Hyperion, is irregularly shaped, in
chaotic rotation, and displays a very unusual surface
morphology (third row, left); Saturn’s satellite
Enceladus is one of several in the solar system that has
active geysers on its surface (third row, right); another
small Saturnian satellite, Mimas, displays an immense
impact crater on one hemisphere (fourth row, left);
Saturn’s satellite Iapetus is black on one hemisphere
and white on the other, and has a high ridge circling it
at the equator (fourth row, right); Uranus’ outermost
major satellite, Miranda, has a complex surface
morphology suggesting that the satellite was disrupted
and reaccreted (bottom row, left); Neptune’s one large
satellite, Triton, displays a mix of icy terrains and ice
vulcanism (bottom, right).
