List of former planets

High school (ages 12+)
Space & Astronomy

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/list-of-former-planets

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the pluto's reclassification year?Pluto was reclassified as a dwarf planet by the IAU in 2006
2. What does it mean that some planets are no longer planets?When scientists learn more about a space object, they sometimes change its name. If it doesn't meet the new rules, it can be called something else, like a dwarf planet or an asteroid.
3. Why was Pluto called a planet and then changed to a dwarf planet?Pluto was once the ninth planet because people didn't know about many other similar objects. When scientists found Eris, they realized many more objects like Pluto exist, so they made new rules and moved Pluto to the dwarf planet group.

Heliocentric Model: A model of the solar system where the Sun is at the center, and planets orbit it.
Hydrostatic Equilibrium: The state where a celestial body's gravitational force pulling inward is balanced by its internal pressure pushing outward, resulting in a nearly round shape.
Exoplanetology: The scientific study of planets that orbit stars outside of our solar system.