1. Jovian Planet Moons and Rings
Each planet has multiple moons and seem like “mini-solar systems”
Moons are mostly made of ice, so quite soft and can be more active than similar sized rocky planets/moons
Rings are made of individual small particles, orbiting like “micromoons”

2. A “Mini-Solar System”
Many moons, 4 big ones found by Galileo, another 12 over 350 years from the Earth
Dozens more by spacecraft imaging on fly-bys/orbits: most are captured asteroids
Jupiter also has a narrow, faint ring system

3. JUPITER: The Galilean Moons
Io and Europa -- smaller, rockier, differentiated
Ganymede and Callisto -- further, bigger and icier; Ganymede is the biggest Moon in SS

4. Jupiter: Surrounded by Moons
Named after lovers of Jupiter from mythology Galilean all have synchronous orbits
Almathea: inside them (181,000 km from center; 260 km diameter) -- discovered in 1892 by Barnard
4 even smaller moons found inside Galilean (found by Voyagers and early Galileo)
4 moons around 11,000,000 km out: e and i high: captured asteroid(s); known from Earth
4 more captured moons around 23,000,000 km out: these have retrograde orbits.
A total of 63 known in largest number of confirmed moons

5. IO: most active object in SS
a = 422,000 km; D = 3640 km; M = 1.22 MMoon
Multicolored surface: yellow, orange, red, brown, and white: sulfur & S compounds
Rocky mantle; Fe/FeS core:  = 3.5 g/cm3
Strong tidal flexures: P = 1.77d = 1/2 P(Europa) = 1/4 P(Ganymede)  forced heating from resonant orbit
Sulfur volcanoes blasting out particles Very smooth, young ( < 1 Myr) surface:flows Fills up Jupiter's plasma torus: ionized S atoms.

6. Io and its Volcanoes

7. EUROPA: Icy & Oceanic?
a = 671,000 km D = 3130 km M = 0.65 Mmoon  = 3.04 g/cm3
Icy crust kms thick, temporary cracks Colored areas mostly mineral rich ices Probable 100 km thick ocean -- LIFE EXISTS(ED) THERE ????
Surface < 100 Myr old: new ice replacing old
Less heating by tidal flexure than Io, but still a good bit warmed up from resonant orbits

8. Europa: cracked, oozy ice
Liquid water on surface?

9. GANYMEDE: King of the Moons
a = 1,070,000 km D = 5270 km
M = 2.02 MMoon
 = 1.93 g/cm3  very thick ice layer
Rocky mantle, Fe/FeS core Many craters, many old ones survive Grooved terrain  plate tectonics at 3 Gy in the past
Only satellite with a magnetic field

10. Ganymede

11. CALLISTO: Deadest of All Biggies
a = 1,880,000 km D = 4800 km M = 1.46 Mmoon  = 1.83 g/cm3  mixture of rock and ice
More craters, fewer faults, than Ganymede