Measuring the Size of a Small, Frost World
Observing a very rare occultation of a star by Pluto's satellite Charon from
three different sites, including Paranal, home of the VLT, astronomers were able
to determine with great accuracy the radius and density of the satellite to the
farthest planet. The density, 1.71 that of water, is indicative of an icy body
with about slightly more than half of rocks. The observations also put strong
constraints on the existence of an atmosphere around Charon. Read all the
details and see the images in ESO 02/06 at
http://www.eso.org/outreach/press-rel/pr-2006/pr-02-06.html