Pluto Demoted – Now There Are Eight

Pluto was demoted to a non-planet — or more accurately, a dwarf-planet — on August 24th, 2006. Many people are on each side of the fence on this issue, but I, for one, agree that Pluto was mis-classified as a planet due to lack of information at the time of its discovery and was rightly demoted to a non-planet

When Clyde Tombaugh discovered Pluto in 1930, there was little known about the vast region of similarly-sized bodies now known as the Kuiper Belt. The Kuiper Belt is the spherical region of space encircling our solar system outside the orbit of Neptune. This region of space is littered with icy bodies that orbit our sun in various orbits. Most are smaller than Pluto, but at least one (admiringly named Xena by its discoverer) is larger than Pluto. This discovery rekindled the debate over what constitutes a planet that has long simmered in smoky, dimly-lit back rooms of observatories for years.

There was fear among astronomers for years leading up to the final (for now) decision about what constitutes a planet that a precise definition could either abolish Pluto or could expand the number of planets to hundreds as new discoveries are made. Since the discovery of Ceres in 1801 by Guiseppi Piazzi, some wondered what objects should be considered “A Planet” and what objects should not be given that prestigous title. When Clyde discovered an object orbiting the Sun in the far reaches of our system, the object was estimated to be much larger than it turned out to be. A combination of mistaken size and an overzealous lot at the Astronomical Society led to the naming of Pluto as the ninth planet. A mistake that has taken 76 years to correct

Many argued that Pluto had been a planet for too long to now say that it wasn’t a planet. I understand some of the sentimental feelings, but science should not be about sentimentalism. The Earth was believed to be flat for centuries, but we now say that is not correct; that it is a spherical shape. They also said for centuries that the Earth was the center of the Universe and everything orbited around us; but not now. Pluto was a planet for a mere 76 years. Why should it be different?

Sure, books will need to be reprinted, solar system models will have to be redesigned, and school children will have one less thing to remember, but we can all take comfort in the fact that Pluto will retain its name and will continue to orbit the Sun as it has for millenia.

Too much time has been spent on trying to find a way to keep Pluto in the family, but, hopefully, the astronomical community can get back to other serious work — like figuring out where all the little green men on Mars went to. They were plentiful in the 50’s and 60′; where’d they go to?

–Mark