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|Pluto: The First Dwarf Planet|
|Pluto is actually smaller than one of Neptune's moons, Triton.|
For many years, Pluto was thought of as the farthest known planet from the Sun. In 2006, astronomers re-classified Pluto as a dwarf planet. This change was made because Pluto is not like the other eight larger planets.
Pluto has a very unusual orbit. Once every 248 Earth years, Pluto swings inside the orbit of Neptune. It stays there for twenty years. During those twenty years, Pluto is closer to the Sun than Neptune. While it is closer to the Sun, Pluto has an atmosphere. This is the result of the methane and nitrogen normally frozen at the poles warming up and thawing out. Once thawed they rise and temporarily form an atmosphere. As it moves toward its farthest point from the Sun, Pluto's atmosphere once again freezes and falls back to the ground at the poles.
Pluto currently has three named moons. Pluto's largest moon, Charon, is half the size of Pluto. In 2005, astronomers observed two more moons of Pluto. The moons were named Nix and Hydra. Recently, two more possible moons have been seen orbiting Pluto. They have not yet been confirmed or named.
What are the names of Pluto's three moons?
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