Astronomy 1021 Chapter Notes - Chapter 8: Orbital Resonance, Galilean Moons, Oort Cloud
11 May 2016
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Saturn: ~85 mearth: its density is less than of water. Gas giants- mostly h and he gas o. Ice giants- mostly hydrogen compounds; water h2o, methane ch4, ammonia nh3; some h, he, and rock o. Beyond the frost line, planetesimals could accumulate ice. Hydrogen compounds are more abundant than rock/metal so jovian planets got bigger and acquired h/he atmospheres. The jovian cores are very similar: ~mass of 10 earths. The jovian planets differ in the amount of h/he gas accumulated. Timing: the planet that forms earliest captures the most hydrogen and helium gas o. Capture ceases after the first solar wind blows the leftover gas away. Location: the planet that forms in a dense part of the nebula forms its core first. Uranus and neptune are dense than saturn because they have less h/he, proportionately, but this explanation doesn"t work for jupiter. High pressure inside of jupiter causes the phase of hydrogen to change with depth.
