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Home/Questions/Why is Pluto not a planet anymore?

🪐 Why is Pluto not a planet anymore?

🍭
0-5
🦸
6-10
😎
11-15
SpaceScience
🍭

Answer for children of age 0-5

Pluto used to be called a planet, but scientists decided it was too small and didn't act like other planets. 🌟 Now, it's called a "dwarf planet"—a tiny planet that lives far away in space!

Pluto is so small that it's even tinier than our Moon! 🚀 But it's still special because it has a big heart-shaped spot on it. ❤️

🌟 Fun fact!

Pluto has five moons! The biggest one is named Charon, and it's almost as big as Pluto itself!

💡Advice for parents

Focus on the idea that Pluto is still special, just in a different way. Use simple comparisons (e.g., Pluto is smaller than Earth’s Moon) and mention its unique features (like its heart-shaped spot) to make it fun.
🦸

Answer for children of age 6-10

In 2006, scientists made new rules about what makes a planet. To be a planet, an object must:

  • Orbit the Sun 🌞
  • Be round like a ball ⚽
  • Have "cleared its neighborhood" (meaning it's the biggest thing in its area of space).

Pluto orbits the Sun and is round, but it shares its space with other icy objects in the Kuiper Belt. That's why it's now a dwarf planet—a small planet-like object!

Fun fact: Pluto sometimes comes closer to the Sun than Neptune! But don't worry, they never crash. 🚀

🌟 Fun fact!

Pluto's surface is so cold (-375°F!) that gases like nitrogen freeze solid and form glaciers!

💡Advice for parents

Explain the three rules simply. Use analogies like "clearing the neighborhood" = being the boss of your space. Mention the Kuiper Belt to show Pluto isn't alone out there.
😎

Answer for children of age 11-15

In 2006, the International Astronomical Union (IAU) redefined what a planet is. Pluto didn't meet all three criteria:

  1. Orbit the Sun: Pluto does this.
  2. Be spherical: Pluto is round due to gravity.
  3. Clear its orbit: Pluto shares its orbit with other objects in the Kuiper Belt (a region beyond Neptune filled with icy bodies).

Because Pluto hasn't "cleared" its neighborhood, it was reclassified as a dwarf planet. There are now five official dwarf planets, including Pluto and Eris (which is actually more massive than Pluto!).

Fun fact: Pluto has a thin atmosphere that freezes and falls as snow when it moves farther from the Sun! ❄️

🌟 Fun fact!

Pluto's orbit is so tilted and elliptical that it takes 248 Earth years to go around the Sun—and for 20 of those years, it's closer to the Sun than Neptune!

💡Advice for parents

Focus on the IAU's scientific process. Discuss how definitions in science can change with new discoveries. Compare Pluto to other dwarf planets to show it's part of a bigger group.