PBL Science

By: Ayla Khan

Dwarf Planets

A dwarf planet is a celestial body representing a small planet, but lacks certain articles in order to be a planet. The IAU classified this definition as the official definition for a dwarf planet.

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Why Are They Responsible For The Classification Of Planetary Bodies?

The IAU is responsible for the naming and classification of planets and their satellites. They have had this responsibility since the early 1900's when the IAU had first been founded in 1919.

IAU Classifies :

* Planet- Celestial body moving in an elliptical orbit around a star.

*Dwarf Planets- A celestial body representing a small planet, but lacks certain things necessary to be a planet.

*A Small Solar System Body- All objects orbiting the Sun that are too small to be a planet or a dwarf planet.

The IAU's view of our solar system changed on August 30, 1992 with the discovery by David Jewitt and Jane Luu when they discovered the trans- Neptunian region. Anything beyond the planet Neptune was classified as a Trans- Neptunian Object.


The IAU, short for International Astronomical Union, is one of the world's largest astronomy families. Their mission is to promote and safeguard the science of astronomy in all its aspects through international cooperation. The IAU was founded in 1919 by Benjamin Baillaud, a French astronomer who became the founding president.

The International Astronomical Union Resolutuion

The IAU Resolution was the decision that the IAU made officially declaring that the solar system consists of eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Anything beyond Neptune was in the Kuiper Belt, which is why when scientists were looking through the belt, Pluto was the first major thing they found, so they classified it as a planet. But in 2006, when the IAU Resolution was established, they booted Pluto out.

The Kuiper Belt

It is a disc- shaped region of icy objects beyond the orbital path of Neptune. Pluto and Eris are the two dwarf planets that are the best known in this icy region of our solar planet.
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