Saturday, October 3, 2009

Is Pluto a planet?

Photo by Mathias Pedersen

Jenna Burleigh

I remember my science teacher once telling us an acronym to remember the names of the planets in the solar system: my very energetic mother just served us nine pizzas. The first letter of each word was meant to signify Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. However, she may end up serving us “nothing” because the fate of the “pizzas” doesn’t look so good.
Q: Is Pluto a planet?

A: Discovered in 1930 by Clyde W. Tombaugh, Pluto became the 9th planet in our solar system. However, a later discovery in 2005 came in the form of an object in the Kuiper belt, and it was even larger than Pluto. Discovery of this object and several others that rivaled the size of Pluto caused the International Astronomical Union (IAU) to determine what exactly a “planet” is.

Prior to these discoveries, no official definition for “planet” existed. In order to be considered a “planet,” the object in question must meet three criteria, as set by the IAU.

One: it must orbit the sun.
Two: it must have the gravity to be able to pull itself into a spherical shape
Three: it must be able to consume or clear other objects in its orbit

The third criterion is where Pluto falls short, since it is smaller than Eris (another object in what is called the Kuiper belt), and not massive enough to clear other objects in its orbit. According to this article, Pluto has been demoted to a “dwarf planet,” as if it were some kind of consolation prize.

It might take some time for those used to “Planet Pluto” to adjust to the fact that Pluto is no longer a planet, but at least there’s finally a clear definition of what a “planet” actually is. As for children, they are going to have to get used to the fact that their very energetic mothers are going to serve them nothing.

1 comment:

  1. Jenna, you did a fairly good job explaining why Pluto is not a planet. However, it would have been better if you had defined "Kuiper belt" and clarified what you mean by "clearing" other objects.