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Large changes in Pluto's atmosphere as revealed by recent stellar occultations


Pluto's tenuous nitrogen atmosphere was first detected by the imprint left on the light curve of a star that was occulted by the planet in 1985 (ref. 1), and studied more extensively during a second occultation event in 1988 (refs 2–6). These events are, however, quite rare and Pluto's atmosphere remains poorly understood, as in particular the planet has not yet been visited by a spacecraft. Here we report data from the first occultations by Pluto since 1988. We find that, during the intervening 14 years, there seems to have been a doubling of the atmospheric pressure, a probable seasonal effect on Pluto.

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Figure 1: Dimming of the stars P126 (20 July 2002) and P131.1 (21 August 2002) during their occultations by Pluto's atmosphere.
Figure 2: Temperature and pressure profiles of Pluto's atmosphere derived from the inversion of the P131.1 light curve.

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We thank the Conseil Scientifique of Paris Observatory and the Programme National de Planétologie for supporting part of the observations of the P126 event in South America. We are grateful to C. Angeli, A. Bruch and D. Lazzaro, who made possible the observational campaign in Brazil, and to W. B. Hubbard for constructive comments.

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Correspondence to B. Sicardy.

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Sicardy, B., Widemann, T., Lellouch, E. et al. Large changes in Pluto's atmosphere as revealed by recent stellar occultations. Nature 424, 168–170 (2003).

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