Pluto,
named after the Greek god of
the underworld, is an apt name for the farthest planet from the Sun.
With an average distance of 39 AU from the Sun, it is a cold, dark world.
Prior to Pluto's discovery by Percival Lowell in 1930, astronomers had
speculated that there was a ninth planet in our solar system or Planet
X. They believed this because the orbits of Neptune and Uranus were
slightly out of step with their predicted mathematical orbits.
In 1978, a scientist discovered
that Pluto has a moon that is almost as big as it is. The new discovery
was called Charon, after the mythological Greek ferryman that transported
the dead across the river Styx into the underworld, the realm of Pluto.
Pluto and Charon have a very
interesting orbital relationship as seen below:
Can you explain why this
happens?