Astronomy 1021 Lecture Notes - Lecture 8: Smog, Orbital Resonance, Tidal Heating
3 Apr 2016
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Document Summary
They difer primarily in their relaive proporions of hydrogen compounds. Jupiter and saturn are made almost enirely of hydrogen and helium. Jupiter has a star-like composiion but lacks the nuclear fusion needed to make it shine (because of its size) Uranus and neptune have are smaller and contain more hydrogen compounds than jupiter and. Diferences in composiion can be traced to their origins. They formed in the outer solar system where its cold enough for hydrogen compounds to condense into ices. Hydrogen was more abundant than rock so planet size grew. Once the planetessimals became massive enough, their gravity allowed them to draw in the hydrogen and helium gas that surrounded them. All 4 grew from ice-rich planetessimals of about the same mass (roughly 10x that of earth) but captured diferent amounts of gas. Jupiter is surprisingly dense because of how massive planets are afected by their own gravity. Jupiter"s extra mass compresses its interior to a much higher density.
