In Class:
Question to Ponder
How long does it take radio signals to travel from the Galileo
satellite orbiting Jupiter to reach us here on Earth?
- a) 1.3 seconds
- b) 15 seconds
- c) 53 minutes
- d) 5 hours
Jupiter has a little miniature Solar System
- Large number of moons orbit Jupiter (somewhere around 30,
depending on who you ask, and what minimum size you think qualifies as a moon).
- Four major moons are called the "Galilean Moons," because they
were discovered by Galileo.
- In order from inside out, they are: Io, Europa, Ganymede, and
Callisto
Jovian exploration
- Voyagers 1 and 2 were launched in 1977 and arrived near Jupiter
in 1980.
- Both were flyby missions.
- Galileo mission launched in 1989, and arrived near Jupiter in
1995.
- Dropped a parachuting probe into the jovian atmosphere.
- Satellite continues to orbit among Jupiter's moons.
Callisto
- Mainly dirty ice
- density (= 1800 kg/m3) suggests a roughly equal
composition of ice and rock
- Surface has lots of both, so this moon is undifferentiated,
and therefore probably hasn't been hot.
- Major feature: Valhalla basin -- like maria on our Moon, it probably
resulted from some large impactor. However, on Callisto, there
was no molten material underneath, so no mare formed.
Ganymede
- Similar density, and therefore presumably similar composition.
- However, the surface looks much more icy.
- Craters seem to be partially filled by slow-flowing ice.
- That means the rock must be inside, and this moon is at least
partially differentiated.
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