What Is a Dwarf Planet?

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Our solar system is made up of the sun and the eight planets that revolve around it, but it has a lot more going on. Moons, asteroids and other astronomical objects also orbit the sun — and they’re just as exciting as planets and stars.

You may remember learning that the solar system has nine planets, not eight. Scientists used to consider Pluto a planet, but its planetary status changed in 2006. That’s when NASA announced it was reclassifying some large bodies in space; some planets, planetoids and other astronomical objects became newly designated dwarf planets. This affected more would-be planets than Pluto, but this smaller planetary mass got quite a bit of attention when the renaming process happened.


Although it can sound like Pluto was “downgraded,” taking on the new status of “dwarf planet” doesn’t make Pluto and similar masses any less interesting or important for our solar system. Dwarf planets — much like moons, asteroids and other physical masses in space — are like windows that can tell us more about the universe and its many mysteries. Read on to learn more about what defines a dwarf planet, including its size, features and some notable examples, to see how these planetary bodies have furthered our understanding of outer space.