Other Objects in the Solar System
Dwarf Planets
The dwarf planets are celestial objects that do not quite fit in the category of planet or moon. The term dwarf planet was adopted by the International Astronomical Union (IAU) in 2006 to describe objects such as Pluto and Eris. Currently there are only five recognized dwarf planets that are all smaller than Mercury. It is estimated that hundreds or even thousands of potential dwarf planets exist in the solar system, though they have yet to be named. In this interactivity, learn what sets each dwarf planet apart by clicking on each of the tabs. Click the player button to begin.
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In order to be classified as a dwarf planet, the celestial object must include ALL of the following characteristics:
- It must orbit the Sun.
- It must be nearly spherical in shape as a result of its own gravity.
- It does not act as a satellite or moon.
- It does not have a strong enough gravitational force to clear its area of other celestial objects.
Other Members of the Solar System
Have you ever heard that an asteroid came close to colliding with Earth or another planet? While these events are very rare, the occasional collision does take place. Comets, meteors, and asteroids are all celestial bodies that are found in the inner solar system. Trans-Neptunian objects are found much further away past the orbit of the planet Neptune. In the interactivity below, read a short introduction and click on each of the tabs to examine each of the other objects in the solar system.
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Other Members of the Solar System Review
Now that you have learned about the other members of the Solar System, check your knowledge in this non-graded activity. Read each question and select the appropriate answer. Then, click SUBMIT to check your response. Click the player button to get started.