AS101 Lecture Notes - Lecture 18: The Moons, Hershel Greene, Unsolved Mysteries
Document Summary
Voyager 1 and 2 explored the outer planets in the 70"s and 80"s. The galileo spacecraft circled jupiter dozens of times in the 1990"s. The cassini huygens orbiter and probe arrived at saturn in 2004. Planet origins: low density because they formed in the outer solar nebula where water vapour could freeze to form ice particles, ice accumulated in proto-planets with density lower than rocky terrestrial and asteroids. Compared to terrestrials: much larger and more massive, composed mostly of hydrogen, helium. Inside jovian planets: all cores appear to be similar. Made of rock, metal, and hydrogen compounds. 10x the mass of earth: uranus and neptune captured less gas from the solar nebula. Not much time for gas captures before nebula was cleared out by solar wind: only jupiter and saturn have high enough pressure for h & he to exist in liquid and metallic states. Jupiter and other jovian planets are all slightly flattened.
