A new study by a University of Central Florida researcher has become the latest to argue that Pluto should be reclassified as a planet, and that the reasons for its demotion to dwarf planet status in 2006 do not hold much weight.
The debate over whether Pluto is a planet or not had begun to warm up in the early years of the 21st century. After a few years in New York’s Hayden Planetarium presented an exhibition with only eight planets. After years of debates, the International Astronomical Union decided in 2006 that Pluto should no longer be classified as a planet, as it was found unable to “clear” its orbit, or to be the greatest force of gravity inside this orbit. Meanwhile, American scientists Mike Brown and Neil deGrasse Tyson, who pushed for its declassification, respectively became known as “the man who killed Pluto” and the “escape driver” after Pluto has been demoted.
According to the IAU’s criteria, for a celestial body to be called a planet it must:
- be orbiting a star, without being one.
- be massive enough for the effect of its own gravity to give it a spherical envelope.
- dominate its environment, and have cleared the neighborhood around its orbit.
While Pluto responds to the first two elements of this resolution (named 5A), it does not answer the last point. It must be understood here that its gravitational force is not sufficient to attract or repel the bodies around it. That’s why Pluto is no longer a full-fledged planet and was downgraded to a dwarf planet. A decision that did not delight Americans countless astronomers around the world and in America in particular, since it was the only discovery by one of their compatriot, Clyde Tombaugh, in 1930.
Nonetheless, nothing about Pluto is simple. Discussions about the reintegration of Pluto into the planetary club are frequent and heated.
Philip Metzger, planetary scientist from the University of Central Florida, argues that “the IAU definition would say that the fundamental object of planetary science, the planet, is supposed to be a defined on the basis of a concept that nobody uses in their research.”
Metzger also qualifies the definition of a planet adopted by the IAU as sloppy as “the organization did not have to give a straight definition of orbit of compensation. He added that the IAU criteria, if followed to the letter, would disqualify all of the planets in our universe as such, since none of them are really close to clearing their orbit.
Speaking about criteria that could be used instead for the planet classification, Metzger insisted that people should look at “the intrinsic properties of the planet. For example, if a planet is large enough to become spherical. He concluded by saying that Pluto should be classified as a planet as its subterranean ocean and evidence of ancient lakes are among the many features that make the planet dwarf “more vibrant and alive” than Mars, for example.