ASTR 1101 Chapter : Mar16 Rocky Planets Properties
Document Summary
Very cold: ices can condense! only in outer solar system! Very hot: only (cid:1)dense(cid:2) ! minerals (iron-rich) can ! condense at these temperatures! Hot: less dense minerals (e. g. , silicates)! can condense in middle solar system! R = 3m/(4 d)! d = density of body! R = radius of body! g = gm/r2! g = acceleration of gravity at surface! Force = mass * acceleration [newton(cid:2)s 3rd law]! Heating volume r3 [how much radioactive elements are in planet]! Cooling surface area r2 [recall boltzmann(cid:2)s law]! !==> only (cid:1)very big(cid:2) [rocky] planets have tectonics! !==> middle sized planets will have volcanoes but no tectonics! !==> small-sized planets have neither volcanoes nor tectonics! T4 = (1/d2) * (16 lsun / ) # Planets with too small an escape velocity ! Vthermal = typical velocity gas molecule! k = boltzmann(cid:2)s constant = 1. 4x10-23 j/k ! = mass of atom or molecule (kg)! G = gravity constant = 6. 7x10-11 n m2/kg2#
