The Dwarf Planets
Dwarf planets are celestial objects that do not belong into the category of planet or moon. The term "dwarf planet" was adopted by the International Astronomical Union (IAU) in 2006 to describe objects, like Pluto and Eris. Since that time, three other dwarf planets have been classified by the IAU. In this interactivity, learn what sets each dwarf planet apart by clicking on each tab to learn more. Click the player to begin.
Download a printable version of the interactivity above.
Dwarf Planet Guidelines
In order to become a dwarf planet, a celestial object must adhere to several guidelines. Currently, there are only five recognized dwarf planets, and they are all smaller than Mercury. It is estimated that well over another one hundred dwarf planets are ready and waiting for their discovery.
Dwarf planets must adhere to ALL of the following guidelines:
- It must orbit the Sun
- It must have enough mass to be nearly spherical in shape as a result of its own gravity
- It does not act as a satellite or moon
- It is unable to move smaller objects out of their way to clear a path around the Sun
Dwarf Planet Review
Now that you have examined the dwarf planets and their criteria, check your knowledge in this non-graded activity. Read the directions associated with each question and select the appropriate answer. Then, click SUBMIT to check your response. Click the player to get started.