Triton, Pluto and Charon

by: Cruikshank, D. P.

ABSTRACT

On the eve of the Voyager encounter with Neptune and Triton, the knowledge
of the surface and atmosphere of the satellite has made some progress.
Methane, and perhaps molecular nitrogen, appears to dominate the surface
and atmospheric chemistry. Sketchy evidence suggests changes in the dispo-
sition and state of the volatile materials on this body in the past few
years, perhaps in response to the extreme seasons. Pluto and its satellite
Charon are at last revealed in some detail, chiefly resulting from observa-
tions of the mutual transits and occultations of 1985-1990. A stellar oc-
cultation by Pluto in 1988 has given the first detailed information on the
planet's atmosphere. The density of the Pluto-Charon system indicates a
bulk composition consisting of silicates and water ice, suggesting forma-
tion directly from the solar nebula.

Advances in Space Research, ISSN 0273-1177, vol. 10, no. 1, 1990, p. 199-
207.