In 1930, Clyde Tombaugh over-estimated the size of Pluto and it was awarded planetary status. As more evidence was gathered it became clearer that perhaps it was an error.

In 2005 a new object larger than Pluto was identified (2003 UB313) and this caused increasing debate through the scientific community - if Pluto was a planet, then so should this new object.

In 2006, the International Astronomical Union met and agreed that there were three conditions that planets had to meet:

- it must orbit the Sun
- it must be large enough that its gravity makes it spherical
- it must clear its orbit of other objects

As Pluto has an orbit that overlaps with Neptune it can not be classified as a planet. Pluto is now classed as a dwarf planet, along with Pluto, and the asteroids 2003 UB313, Eris and Ceres. In 2008, it was discovered that Eris has a greater diameter, and Pluto can not even claim to be the largest dwarf planet.

Pluto is no longer a planet because it is on the outskirts of an asteroid belt that rings the outside of the solar system. I do not agree with this because schools have been teaching that it is a planet for years, but truth is truth and many people believe that Pluto is just another asteroid on that belt, even though it is a little farther away from the rest and Neptune crosses its path. Planet X was going to be the next planet but soon after that body was discovered the belt was seen and that put Pluto and Planet X out of the running for planets in our solar system.