1. The definition of a planet – A Debate

4. Background Information
The IAU’s definition of a planet:
Object must orbit a star
Object must have enough mass for its gravity to pull it into a spherical shape
Object’s orbit must be free of other objects like asteroids

5. Background information
Pluto resides in the Kuiper Belt, an asteroid belt beyond Neptune’s orbit
Part of Pluto’s orbit goes inside Neptune’s orbit
Pluto is not the largest object in the Kuiper Belt

6. Assignment In groups of 3: Choose a recorder and a speaker
Discuss amongst your group the IAU’s definition of a planet
Does your group agree with it?
Should Pluto be called a dwarf planet?
Come up with your own definition of a planet.
The recorder will take notes as the group discusses the above questions.
The speaker will present the information to the class