This is a drawing showing the orbit of Pluto and the outer planets. It shows the planets on June 1, 1997. In the larger version at least, you can see dots next to the names indicating planet position. In 1997, Pluto was closer to the Sun than Neptune.
Click on image for full size
Pluto has the most eccentric orbit of all the planets in the solar system. Its orbit takes it to 49.5 AU (7.4 billion kilometers) at its farthest point from the Sun. And its orbit takes it as close as 29 AU (4.34 billion kilometers) to the Sun.
That means that Pluto's orbit draws within the orbit of Neptune, as can be seen in this drawing, making Pluto the 8th planet rather than the 9th planet for roughly 20 years at a time. Pluto was the 8th planet from January 1979 to February 1999. Neptune is now the 9th planet for over 200 years!
It takes 248 years for Pluto to complete its orbit. This means that a single Pluto year is 248 earth years long.
In addition to its peculiar orbit, Pluto and its moon Charon are locked together as they orbit each other, so that the same side of each body always faces the other.
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