PLUTO
(a closer look)
Little is known about Pluto's atmosphere, but it probably
consists primarily of nitrogen with some carbon monoxide and
methane. It is extremely tenuous the surface pressure being only a few microbars. Pluto's
atmosphere may exist as a gas only
when Pluto is near its perihelion; for the majority of Pluto's long year, the atmospheric
gases are frozen into ice. Near perihelion,
it is likely that some of the atmosphere escapes to space perhaps even interacting with
Charon. The Pluto Express mission
planners want to arrive at Pluto while the atmosphere is unfrozen.
The unusual nature of the orbits of Pluto and of Triton and the similarity of bulk
properties between Pluto and Triton suggest
some historical connection between them. It was once thought that Pluto may have once been
a satellite of Neptune's, but this
now seems unlikely. A more popular idea is that Triton, like Pluto, once moved in an
independent orbit around the Sun and was
later captured by Neptune. Perhaps Triton, Pluto and Charon are the only remaining members
of a large class of similar objects
the rest of which were ejected into the Oort cloud. Like the Earth's Moon, Charon may be
the result of a collision between
Pluto and another body.
Pluto can be seen with an amateur telescope but it is not easy. There are several Web
sites that show the current position of
Pluto (and the other planets) in the sky, but much more detailed charts and careful
observations over several months will be
required to actually find it. Suitable charts can be created with many planetarium
programs such as Starry Night.