Hemispherical color differences on Pluto and Charon

by: Binzel, R. P.

ABSTRACT

Time-resolved multicolor photometric observations of Pluto-Charon mutual
events have been used to derive individual colors for these two bodies
and to investigate the degree of color differences between their synchro-
nous facing and opposite hemispheres. Pluto is significantly redder than
Charon, where direct measurements of the anti-Charon hemisphere of Pluto
and the Pluto-facing hemisphere of Charon yield B-V magnitudes of 0.867
or - 0.008 and 0.700 or - 0.010, respectively. Both Pluto and Charon are
found to have relatively uniform longitudinal color distributions with
1-sigma upper limits of 2 percent and 5 percent, respectively, for any
large-scale hemispherical color asymmetries. Thus, a previous suspicion
of a significant color asymmetry on Charon is not confirmed. Instead the
data may be attributed to a direct detection of polar caps on Pluto.

Science, ISSN 0036-8075, vol. 241, Aug. 26, 1988, p. 1070-1072.