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Updated: Mar 24, 2026

Scattering And Absorption of Light in Planetary Regoliths
Published on: July 1, 2019
The atmosphere of Pluto as observed by New Horizons
G Randall Gladstone1, S Alan Stern2, Kimberly Ennico3
1Southwest Research Institute, San Antonio, TX 78238, USA. University of Texas at San Antonio, San Antonio, TX 78249, USA. rgladstone@swri.edu.
Abstract:
Observations made during the New Horizons flyby provide a detailed snapshot of the current state of Pluto's atmosphere. Whereas the lower atmosphere (at altitudes of less than 200 kilometers) is consistent with ground-based stellar occultations, the upper atmosphere is much colder and more compact than indicated by pre-encounter models. Molecular nitrogen (N2) dominates the atmosphere (at altitudes of less than 1800 kilometers or so), whereas methane (CH4), acetylene (C2H2), ethylene (C2H4), and ethane (C2H6) are abundant minor species and likely feed the production of an extensive haze that encompasses Pluto. The cold upper atmosphere shuts off the anticipated enhanced-Jeans, hydrodynamic-like escape of Pluto's atmosphere to space. It is unclear whether the current state of Pluto's atmosphere is representative of its average state--over seasonal or geologic time scales.
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