GO IN DEPTH

Is Pluto a Planet?

Introduction

You may have heard about the International Astronomical Union's decision to redefine Pluto from a planet to a dwarf planet. But what exactly is a planet and what is a dwarf planet? Read on to find out more.


Exploration

Go through the slideshow at the top of this esheet. Use the information from the slideshow to help you answer these questions on your What Is a Planet? student sheet:

  • According to the International Astronomical Union (IAU), what are the characteristics of a planet?
  • What are some examples of planets?
  • According to the IAU, what are the characteristics of a dwarf planet?
  • What are some examples of dwarf planets?
  • Why might it be useful to define the characteristics of a planet or a dwarf planet?

To learn more about Pluto, you should go to Pluto and the Developing Landscape of Our Solar System, on the IAU site. Read just the first two sections: The Discovery of Pluto and The Changing Landscape of the Solar System.

Now click on the "Video" tab in the media player above to watch the Conversations with a Scientist: Michael Brown, in which Dr. Brown discusses the solar system's bodies and his role in the redefinition of Pluto from planet to dwarf planet.

Use the information from the reading and the video to help you answer these questions on the Is Pluto a Planet? student sheet:

  • When was Pluto discovered? Who made the discovery?
  • What are some characteristics of Pluto?
  • What happened on August 20, 1992, and how did it change our view of the solar system?
  • What did Mike Brown, Chad Trujillo, and David Rabinowitz discover on October 21, 2003? What is its significance?
  • What happened in August 2006?
  • According to Michael Brown, how did this decision affect our perception of the solar system?
  • Why do you think Dr. Brown says that our picture of the solar system was a “cartoon picture”?
  • Where is the Kuiper Belt located?
  • What three dwarf planets did Dr. Brown and his team discover?
  • According to Dr. Brown, what is the mission of a scientist?
  • What are some of the problems encountered by scientists involved in this kind of research?
  • What was Dr. Brown’s reaction to the demotion of Pluto and the “tenth” planet that he had found?
  • What is Dr. Brown’s hope for our view of the solar system?

This esheet is a part of the Is Pluto a Planet? lesson.

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Esheet Details

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AAAS