Pluto

Pluto is the most famous dwarf planet and was considered the ninth planet in our solar system for 76 years! From 1930 to 2006, kids everywhere learned that Pluto was the smallest and most distant planet. But in 2006, scientists decided to create a new category called "dwarf planets" because Pluto is quite different from the eight main planets. Even though it's no longer called a planet, Pluto is still an incredibly fascinating and special world!

Pluto lives way out in a region called the Kuiper Belt, which is like a doughnut-shaped ring of icy objects beyond Neptune. What makes Pluto really interesting is that it has five moons, including Charon, which is so big that some scientists think of Pluto and Charon as a "double planet" system. They're so close in size that they actually orbit around each other! Pluto is a cold, rocky world covered in nitrogen, methane, and carbon monoxide ice.

For decades, Pluto remained a mysterious world at the edge of our solar system, too far away and too small for even our best telescopes to see clearly. That all changed in 2006 when NASA launched the New Horizons spacecraft on an incredible 9.5-year journey to visit Pluto. This amazing mission was like sending a robot detective to solve the mysteries of the most distant world we'd ever explored!

New Horizons made history in July 2015 when it flew by Pluto and sent back the first close-up pictures of this distant world. Scientists were amazed to discover that Pluto is much more interesting and active than anyone expected! The spacecraft found evidence of geological activity, a thin atmosphere, possible underground ocean, and that famous heart-shaped feature that captured the world's imagination. New Horizons is still traveling through the Kuiper Belt, studying other mysterious objects in the outer solar system!