Definition of planet

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/definition-of-planet

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. Who discovered Definition of planet?The trans-Neptunian object Eris
2. What is the historical term origin?Greek 'asteres planetai' meaning 'wandering stars'
3. What is the modern geophysical criterion?Achieved hydrostatic equilibrium, resulting in a nearly spherical shape
4. What is a planet?A planet is a space object that orbits the Sun, is round because its gravity makes it spherical, and has cleared its orbit of other small objects.
5. Why does Pluto not count as a planet?Pluto is round and orbits the Sun, but it hasn't cleared its orbit of other objects, so it is not considered a planet.