Pluto's Atmosphere

Explanation: Study of Pluto's atmosphere by the occultation of a star on June 9, 1988. If Pluto had no atmosphere, the light curve would have vertical sides, but instead, it has sloped sides, whose exact shape can be used to determine the density profile of the atmosphere. Based on the density profile and the low gravity of the planet, the average molecular weight can be determined, and is about 28, which suggests that nitrogen molecules are the primary component of the atmosphere.

Pluto

Image credit: J.L. Elliot, E.W. Dunham, A.S. Bosh, S.M. Slivan, L.A. Young, L.H. Wasserman, R.L. Millis.