Pluto- Lydia Bagwell FA2011

Pluto was once thought to be the ninth planet in our solar system. Now it is not considered a planet but a Dwarf Planet found in the Kuiper Belt.

History of (Topic)

Pluto was discovered by America's very own Clyde W. Tombaugh from Arizona in 1930. However, Neil deGrasse Tyson, the Director of the Hayden Planetarium at the Rose Center for Earth and Space, built a planetarium and built models of every planet except Pluto. The only mention Tyson made to Pluto was the small section on a wall that states that Pluto is in the Kuiper Belt. This started a world-wide debate on why Pluto is even considered a planet. Astronomers at the XXV1th General Assembly of the International Astronomical Union, back in August of 2006, decided that a planet needs to be round and orbit the Sun, have enough gravity to pull itself into a spherical shape, and it needs to have cleared "the neighborhood" of its orbit. Pluto is round and orbits the Sun and even has enough gravity to pull itself into a spherical shape, but it has not cleared "the neighborhood" of its orbit. According to the IAU, this means that Pluto is not a planet. But because Pluto does follow two of the three requirements, it is considered to be a Dwarf Planet.

Application of (Topic)

The discovery of Pluto led to other interesting discoveries in our Solar System, such as Eris and Ceres. Eris and Ceres are both considered Dwarf Planets. Pluto isn't good for much, other than to tell us that there are smaller, planet-like objects that also orbit the sun. Pluto is even smaller than the earth's moon; however, it is still the biggest known object in the Kuiper Belt. (The Pluto Files)
external image Pluto%20size%20comparison.gif


  1. Beiser, A. (1988). Physical Science (2nd Edition). New York, NY: McGraw Hill
  3. The Pluto Files

This WikiPage developed by Lydia Bagwell- FA2011