Pluto explained to kids

Pluto is a dwarf planet in our solar system. It's the second-largest known dwarf planet, after Eris. It was discovered in 1930 by Clyde Tombaugh. Pluto is very small. Its diameter is only about 2,370 km (1,473 miles). That's only about two-thirds the diameter of our moon! Pluto is so small and far away that it's often hard to see, even with a telescope. Pluto is very cold. Its average temperature is -229 °C (-380 °F). That's colder than any other planet in our solar system! Pluto is so cold because it's so far from the Sun. It's about 40 times farther from the Sun than Earth is. Pluto has five known moons: Charon, Styx, Nix, Kerberos, and Hydra. Charon is the largest of Pluto's moons. It's about half the size of Pluto! Pluto and Charon are sometimes called a "double planet" because they orbit each other. Pluto is named after the Roman god of the underworld. The underworld is the place where people go when they die, according to some ancient beliefs. Pluto used to be considered a planet. But in 2006, the International Astronomical Union decided that Pluto didn't fit the definition of a planet. They said that a "planet" must orbit the Sun, be round, and be the largest object in its orbit. Since Pluto doesn't orbit the Sun and isn't round, the IAU decided it wasn't a planet.