Blog 5: The Controversy Behind Pluto’s Planethood

Pluto orbits our Sun far out past Neptune, and has been the source of controversy as we have learned more about it. The argument centers around whether this celestial object should be defined as a planet or a dwarf planet. This leads to an even bigger question: what separates a dwarf planet from a planet?

Simply put, a celestial object must meet three requirements in order to be considered a planet: it must orbit a star, be massive enough to force itself into a sphere, and must have enough mass to clear out a path on its orbit because of its gravitational pull. Under this definition, Pluto seems to meet the requirements for planet-hood, and from 1930 to 2006, it was acknowledged as the ninth planet in the Solar System. As telescoping technology improved, however, the Kuiper Belt, a collection of smaller objects orbiting past the path of Neptune, was discovered. Along with it, Eris was discovered, and some argued that it met the requirements to be a planet. This sparked debate about the nature of planets, and both Eris and Pluto were put into a new category, the dwarf planet.

The debate still rages as to whether Pluto should be included as a planet. Because the old definition, one that at times included the Sun and Moon, was so broad an unscientific, many thought that any major restriction on planethood based on an attempt to artificially restrict the amount of planets in our Solar System was arbitrary at best. Because Pluto exists in the region of the Kuiper belt, it does not fit the criterion that a planet must clear out objects in its orbit. This does not stop many from believing, however, that Pluto deserves all the recognition given any other planet in our Solar System. What do you think?

Pluto

Sources:

Space

NASA