Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earths?
Mars lost most of its atmosphere long ago to the solar wind due to a lack of a meaningful electromagnetic field. Saturn’s Titan has an atmosphere denser than Earth’s, yet Titan is a smaller body than Mars. Why hasn’t the solar wind carried Titan’s atmosphere away? Roughly speaking, at the distance of Saturn, the solar electromagnetic power per unit area and solar wind flux are sufficiently low that elements and compounds that are volatile on the terrestrial planets tend to accumulate in all three phases. Titans surface temperature is also quite low, about 90 K. Therefore, the mass fractions of substances that can become atmospheric constituents are much larger on Titan than on Earth. In fact, current interpretations suggest that only about 70% of Titans mass is silicates, with the rest consisting primarily of various H2O ices and NH3-H2O (ammonia hydrates). NH3, which may be the original source of Titans atmospheric N2, may constitute as much as 8% of the NH3-H2O mass. Much of the orig
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- Why does Titan, in spite of being smaller than Mars, have an atmosphere more dense than Earths?