3. Units of Chapter 8 The Galilean Moons of Jupiter The Large Moons of Saturn and Neptune The Medium-Sized Jovian Moons Planetary Rings Pluto and Its Moon Is Pluto a Planet?
4. 8.1 The Galilean Moons of Jupiter All four jovian planets have extensive moon systems, and more are continually being discovered. The Galilean moons of Jupiter are those observed by Galileo: Io, Europa, Ganymede, and Callisto.
5. 8.1 The Galilean Moons of Jupiter This image shows Jupiter with two of its Galilean moons.
6. 8.1 The Galilean Moons of Jupiter The Galilean moons and their orbits:
9. 8.1 The Galilean Moons of Jupiter Io is very close to Jupiter, and also experiences gravitational forces from Europa. The tidal forces are huge, and provide the energy for the volcanoes. Cause of volcanism: Gravity !
10. 8.1 The Galilean Moons of Jupiter Europa has no craters; surface is water ice , possibly with liquid water below Tidal forces stress and crack ice; water flows, keeping surface relatively flat
11. 8.1 The Galilean Moons of Jupiter Ganymede is the largest moon in the solar system – larger than Pluto and Mercury History similar to Earth’s Moon, but water ice instead of lunar rock
12. 8.1 The Galilean Moons of Jupiter Callisto is similar to Ganymede; no evidence of plate activity
13. 8.2 The Large Moons of Saturn and Neptune Titan has been known for many years to have an atmosphere thicker and denser than Earth’s; mostly nitrogen and argon Makes surface impossible to see; the picture at right was taken from only 4000 km away:
14. 8.2 The Large Moons of Saturn and Neptune Infrared image of Titan, showing detail, and possible icy volcano Few craters, consistent with active surface Complex chemical interactions in atmosphere
15. 8.2 The Large Moons of Saturn and Neptune The Huygens lander (left) took these images of the surface of Titan.
16. 8.2 The Large Moons of Saturn and Neptune Trace chemicals in Titan’s atmosphere make it chemically complex
17. 8.2 The Large Moons of Saturn and Neptune Triton is in a retrograde orbit; its surface has few craters , indicating an active surface Nitrogen geysers have been observed on Triton, contributing to the surface features.
18. 8.3 The Medium-Sized Jovian Moons Densities of these moons suggest that they are rock and water ice
19. 8.3 The Medium-Sized Jovian Moons Moons of Saturn, in natural color. Note the similarities, as well as the large crater on Mimas.
21. 8.3 The Medium-Sized Jovian Moons Miranda shows evidence of a violent past, although the origin of the surface features is unknown.
22. 8.4 Planetary Rings The ring system of Saturn is large and complex, and easily seen from Earth. The other Jovian planets have ring systems as well.
23. 8.4 Planetary Rings The rings are not solid; they are composed of small rocky and icy particles.
24. 8.4 Planetary Rings Our view of Saturn’s rings changes as it moves in its orbit.
25. 8.4 Planetary Rings The Roche limit is where the tidal forces of the planet are too strong for a moon to survive; this is where rings are formed.
27. 8.4 Planetary Rings Voyager probes showed Saturn’s rings to be much more complex than originally thought Earth is shown on the same scale as the rings
33. 8.5 Pluto and Its Moon Pluto was discovered in 1930. It was thought to be needed to explain irregularities in the orbits of Uranus and Neptune, but it turned out that there were no such irregularities.
34. 8.5 Pluto and Its Moon Pluto’s moon, Charon , was discovered in 1978. It is orbitally locked to Pluto, and about a sixth as large. There may be two other moons as well.
35. 8.5 Pluto and Its Moon Its orbit is at a large angle to the plane of Pluto’s orbit:
36. 8.6 Is Pluto a Planet? The first Kuiper belt objects were observed in the 1990s, and more than 700 are now known. Some of them are comparable in size to Pluto. Is Pluto merely the closest Kuiper belt object? If so, should we continue calling it a planet?
37. 8.6 Is Pluto a Planet? If Pluto is a planet, why not 2003 UB313?
