The thermal structure of the upper atmosphere of Mars has been theoretically investigated. The exospheric temperature, for a pure CO(2) model atmosphere, lies between 400 degrees and 700 degrees K. The origin of the Martian atmosphere is discussed in the light of these results.

Observations of the 2007 March 18 occultation of the star P445.3 (2UCAC 25823784; R = 15.3) by Pluto were obtained at high time resolution at five sites across the western United States and reduced to produce light curves for each station using standard aperture photometry. Global models of Pluto’s upper atmosphere are fitted simultaneously to all resulting light curves. The results of these mo...