Classical planet

High school (ages 12+)
Space & Astronomy

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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/classical-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. What is the observational criteria for classical planets?Visible to the naked eye and exhibiting apparent motion against fixed stars
2. What is the greek etymology?The term 'planet' originates from the Greek 'planētēs', meaning 'wanderer'
3. Why were the Sun and Moon called planets?In ancient times the Sun and Moon were called planets because they were the brightest wandering objects and moved against the fixed stars, just like the other planets.
4. How did ancient astronomers use classical planets?They tracked the planets' paths to make calendars, tell time, and help sailors navigate, and they also believed each planet had special powers that could affect people.

Ecliptic: The apparent path of the Sun across the celestial sphere over the course of a year.
Retrograde motion: The apparent backward movement of a celestial body in the sky relative to the background stars.
Hydrostatic equilibrium: The state where a celestial body's shape is determined by the balance between its gravity and internal pressure, resulting in a spherical form.
Clearing the neighborhood: A criterion for a planet meaning it is gravitationally dominant in its orbital region, having removed or accreted most other objects.