New Definition of a Planet

New Definition of a Planet

A new ruling by the International Astronomy Union changes the defintion of what a planet is and has implications for the sudy of astronomy. The new ruling is listed below. The GCSE Astronomy specification adapts well with this as the specification states:

 

Describe the main differences between Pluto and the other major planets, and the grounds for believing that Pluto could be classified as an example of a new type of object in the Solar System.

 

 

This resource now includes notes to the effect of the planet ruling.

 

The Edexcel astronomy website clarifies what it means for this course:

 

Pluto (11/09/2006)
Regarding the recent reclassification of Pluto as a dwarf planet Edexcel will be accepting definitions of Pluto as either:
a) a planet or
b) a dwarf planet
in examination answers. When the specification is redeveloped we will address this issue again

New Ruling

- Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune to remain as Planets

- Pluto to be known as a Dwarf planet.

- Others will be considered in the future. In the meantime they are to be known a Plutonion like objects

- All other bodies to be known as Small Solar System Bodies

 

More information can be found on the IAU website. See a summary on Wikipedia entry is more insightful