Is Pluto a Planet?
Learning Objective
I can argue whether Pluto should be classified as a planet using evidence and reasoning.
Key Concepts
The ancient Greeks called objects that moved against the background of stars 'planetes', meaning wanderer.
According to the IAU, a planet must orbit the sun, have sufficient mass to be nearly round, and clear its neighborhood of other objects.
Pluto is considered a dwarf planet because it has not cleared its neighborhood and resides in the Kuiper Belt.
Practice Questions
This lesson includes 12 practice questions to reinforce learning.
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1. Before the 20th century, what was the primary method for distinguishing planets from stars?
2. Why did the discovery of objects like Ceres, Pallas, Juno, and Vesta lead to a reclassification of celestial bodies in the 19th century?
3. What event in 2005 reignited the debate about the definition of a planet?
...and 9 more questions
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What Is A Planet?
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