Many people have written to me wanting to know whether or not Pluto is classified as a planet. This post will answer that question and explain the reasons behind the classification.
Is Pluto a Planet?
Since 2006, Pluto is not longer classified as a planet. Before then, most people thought the Pluto was the outermost planet in our solar system. So why the change? Well the International Astronomical Union (IAU) got together in 2006 and decided to define what a ‘planet’ actually was. They came up with three conditions that had to be met before something is called a planet.
- The body must orbit the Sun.
- Due to the gravity of the object, it has a spherical (circular) shape.
- It should have the most dominant gravity of any object in its orbit.
While Pluto fits the first two criteria, it fails the third. Therefore, Pluto is not considered a planet.
So what is Pluto?
Pluto is called a ‘dwarf’ planet. There are many objects past Neptune now called ‘dwarf’ planets. Any body that fulfills the first two criteria for a planet listed above but fail the third are known as dwarf planets. Note that many people were unhappy with the reclassification and some still refer to Pluto as a planet.
Other Posts on the Solar System