Formation of the Post-lunar Atmosphere

Abstract

The early Earth’s atmosphere was much more massive than today. Before the condensation of water and the subsequent dissolution of CO ₂ that precipitated into carbonates, the partial pressures of H ₂ O and CO ₂ were about 270 bars and 60 bars, respectively. Today, planetary exploration has revealed that the atmospheres of 8 planets and 3 of their approximately 120 satellites have a structure rather similar to that deduced from the vertical temperature profile of the contemporary Earth’s atmosphere, which shows that the temperature alternately decreases and increases with height (troposphere, stratosphere, mesosphere, and thermosphere). In particular, because the giant planets and Venus are all topped by a high-temperature low-density thermosphere (Dowling, 1999), we can safely assume that the early Earth had also a thermosphere.