Solution: Planetary Atmospheres. (a) The temperature near

Chapter 18, Problem 18.74

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Planetary Atmospheres. (a) The temperature near the top of Jupiters multicolored cloud layer is about 140 K. The temperature at the top of the earths troposphere, at an altitude of about 20 km, is about 220 K. Calculate the rms speed of hydrogen molecules in both these environments. Give your answers in m>s and as a fraction of the escape speed from the respective planet (see 18.72). (b) Hydrogen gas 1H22 is a rare element in the earths atmosphere. In the atmosphere of Jupiter, by contrast, 89% of all molecules are H2. Explain why, using your results from part (a). (c) Suppose an astronomer claims to have discovered an oxygen 1O22 atmosphere on the asteroid Ceres. How likely is this? Ceres has a mass equal to 0.014 times the mass of the moon, a density of 2400 kg>m3 , and a surface temperature of about 200 K.