Discovered by William Lassell in 1846, Triton is one of the most
interesting moons in the Solar System, and one which has increasingly been studied by scientists.
Triton a pretty large moon, having a diameter of 2,700 km and is Neptune's
seventh satellite. It has only been visited by one space probe, the
Voyager 2, and as such we dont have too much information about it yet, although a
mission to Triton sometime in the future is expected.
Triton is unusual as a moon in quite a number of ways. Firstly it is
tilted 157 degrees to Neptune's axis, and even more towards the Sun, so
it is prone to large seasonal changes in temperature.
These changes in temperature are believed to be the cause of Triton's
strange volcanoes discovered by Voyager which, instead of erupting
rocks like conventional volcanoes here on Earth or on Venus, spurts
out what is believed to be liquid nitrogen or methane compounds.
Triton is fairly crater-free, implying a young surface. It is also
incidentaly a very cold surfce, with temperatures dropping to just 34.5
K (-235 C). Like Mars' moon Phobos, Triton is expected to, sometime in
the distant future, crash into Neptune, due to a combination of
Triton's (unusual) retrograde orbit and tidal interactions with Neptune.
The high density of Triton (denser even than Saturn's ice moons), along
with its exceptional retrograde orbit has led many scientists to
believe that it is a celestial object captured by Neptune some time ago.