Two additional Pluto related facts are these:
- Due to the mass and proximity of Pluto's moon, Charon, the centre of mass for the pair is located between them and not inside either body.
- Pluto only has an atmosphere for 20 to 30 years out of each 248 year orbit of the Sun. During the rest of that time the planet is further away from the Sun, making it colder, so the atmosphere freezes.