Dwarf Planets and Pluto

Lab Brief #4

🎯 Your mission

Master the concept. Use it tomorrow.

⚡ The twist

The light you see now started its trip a long time ago.

What you'll learn

Pluto was reclassified as a dwarf planet in 2006 because it has not cleared other objects out of its orbit. Dwarf planets such as Pluto, Ceres, and Eris orbit the sun but are much smaller than the eight main planets.

Key words

dwarf planet
A body that orbits the Sun and is round under its own gravity but has not cleared other objects from its orbit.
orbital clearing
The third condition in the planet definition: a planet must have swept its orbital region free of comparable bodies.

Make a hypothesis first

Guess: how big does that look from here vs. from there?

Say your guess out loud — then find out if you were right.

Step 1 of 4 · Read

Think about what you just learned: say what "dwarf planet" and "orbital clearing" mean in your own words before you start.

Step 2 of 4 · Do

Write the three conditions of the 2006 planet definition as a decision flowchart, then run Earth, Pluto, Ceres, Eris and the Moon through it. Record which condition each body fails, if any, and where the classification actually turns.

Step 3 of 4 · Observe

Record what actually happened, including anything that did not match what you expected.

Step 4 of 4 · Record

Write a conclusion that answers the question this lesson opened with, and state your uncertainty.

Question 1 of 3

Pluto was reclassified because it has not:

How sure are you?😐 maybe

Question 2 of 3

Which condition do both Pluto and Earth satisfy?

How sure are you?😐 maybe

Question 3 of 3

Ceres, Pluto and Eris are all classified as:

How sure are you?😐 maybe

Mind = blown

🌌 If you could drive a car straight up at highway speed, you'd reach space in under an hour.

Nice work!

You got 0 of 3 right.

Next: Black Holes All lessons

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✨ More to explore

🌍 Where you see this in real life: GPS, weather forecasts, and the seasons all rely on this.

🏆 Stretch challenge (try it this week): Find a constellation in the sky. Look it up. Tell someone its story.

👨‍👩‍👧 For the dinner table: “If you could visit any planet, which would you pick and why?”

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