1. Moons of the Giant Planets
Europa

2. Callisto is the outermost of Galilean moons at a distance of 1
Callisto is the outermost of Galilean moons at a distance of 1.2 million miles.
It is in synchronous revolution around Jupiter every 17 days.
The moon has a heavily cratered surface that has seen little change over the last 4.4 billion years.
CALLISTO

3. Callisto froze solid before the process of differentiation occurred
Callisto froze solid before the process of differentiation occurred. It is a geologically dead world.
CALLISTO

4. Closeup
of Callisto

5. GANYMEDE Ganymede is the largest moon in the Solar System.
Parts of its surface are very old like Callisto but others are relatively young, perhaps a billion years old.
Ganymede may have a rocky, metallic core.
Tidal forces may occasionally heat the interior and cause water to erupt and resurface portions of the moon.
GANYMEDE

6. Closeup of Ganymede

7. Europa is predominantly a rocky world with an ice-covered surface that is crisscrossed with cracks and low ridges.
Few craters are evident.
The ice appears to be the frozen surface of a great water ocean that has broken up and refrozen many times.
EUROPA

8. Tidal forces may generate enough heat to keep water in the liquid state not too far beneath the surface layer of ice.
EUROPA

9. Closeup of Europa

10. IO is a close twin our Moon with about the same size and density.
Io has active volcanoes on its surface. Volcanoes emit hot rocky lava, sulfur and sulfur dioxide.
The sulfur and sulfur dioxide recondense in the cold and snow down upon Io’s surface. IO

11. Io is constantly resurfacing itself.

12. Closeup of Io

13. Moons of Saturn
19 Moons and Massive Ring System
Titan is most significant satellite and the only moon with a significant atmosphere
Ring material size of ping-pong, tennis and basketballs.

14. Saturn’s Titan is about the size of Jupiter’s Ganymede and is about half ice and half rock.
It is the only moon to have a substantial atmosphere.
The atmospheric surface pressure is 1.6 times that of Earth. Io

15. Titan’s atmosphere is composed mostly of methane
Titan’s atmosphere is composed mostly of methane. Nitrogen and hydrocarbon compounds are also present.
Methane clouds composed of shroud the surface. The surface is probably covered with methane ice and perhaps methane oceans. Io

16. Tethys
Tethys's icy surface is heavily cratered and contains cracks caused by faults in the ice. There is one enormous trench on Tethys about 65 kilometers wide and extending from above the center to the extreme left. It covers three-fourths of Tethys' circumference. The fissure is about the size scientists would predict if Tethys were once fluid and its crust hardened before the interior. The canyon has been named Ithaca Chasma.

17. Enceladus:
Enceladus is one of the innermost moons of Saturn. Enceladus reflects
almost 100 percent of the sunlight that strikes it.
The uncratered regions are geologically
young and suggest that Enceladus
has experienced a period of relatively
recent internal melting.
The rims of several craters
near the lower center of the
picture have been flooded
by the smooth terrain.

18. Dione
Dione was discovered in It is an icy body with a density of
1.43 gm/cm3, which makes it the densest moon of Saturn other than Titan.
Dione is probably composed of a rocky core making up one-third of the
moon's mass, with the rest water-ice. Dione's icy surface includes heavily
cratered terrain, moderately cratered plains, lightly cratered plains, and
wispy material.

19. Mimas
One of the craters, named Herschel, is surprisingly large in comparison
to the size of the moon. The crater is 130 kilometers wide, one-third the
diameter of Mimas. Herschel is 10 kilometers deep, with a central mountain
almost as high as Mount Everest on Earth. This central mountain rises
6 kilometers above the crater floor. This impact probably came close to
disintegrating the moon.

20. Moons of Uranus
18 Moons and 11 Dark Rings
Miranda – A Moon that may have broken up and then reassembled.
Moons of Neptune
8 Moons
Triton – A large satellite in retrograde orbit

21. Miranda
Its surface is unlike anything in the Solar System with features that are
jumbled together in a haphazard fashion.
Miranda consists of huge fault canyons as deep as 20 kilometers
terraced layers and a mixture of old and young surfaces.

22. It is believed that Miranda may have been shattered as many as five times
during its evolution.
After each shattering the moon would have reassembled from the remains
of its former self with portions of the core exposed and portions of the
surface buried.

23. Cutting across the ridges and valleys are many faults
Cutting across the ridges and valleys are many faults. The largest fault
scarp, or cliff, is seen below and right of center. The fault may be 5 km (3 mi)
high, or higher than the walls of the Grand Canyon on Earth.

24. Miranda

25. Io Triton is the largest moon of Neptune.
It has the coldest temperature of any object unmanned spacecraft have visited – degrees above Absolute Zero.
Triton is so cold that N and CH4 are frozen on its surface.
The moon is 75% rock and 25% water ice. Io