Download this article
- PDF (369 KB)

Back to the Table of Contents

Explained in 60 Seconds: Why is Pluto not a Planet? (page 04)
Chris Marshall

On 24 August 2006 an International Astronomical Union (IAU) resolution changed the shape of the Solar System and redefined what it meant to be a planet. As a result, Pluto, the smallest and most recently discovered planet in the Solar System, became a dwarf planet.