On March 24, 2016, NASA released an image captured by its New Horizons spacecraft of what it says appears to be a frozen, former lake of liquid nitrogen. The feature is located in a mountain range just north of Pluto’s informally named Sputnik Planum. (NASA/JHUAPL/SwRI)

On March 24, 2016, NASA released an image captured by its New Horizons spacecraft of what it says appears to be a frozen, former lake of liquid nitrogen. The feature is located in a mountain range just north of Pluto’s informally named Sputnik Planum. (NASA/JHUAPL/SwRI)

In 2006, members of the International Astronomical Union or the IAU, an organization recognized as the authority for naming celestial bodies, voted on a set of characteristics that define what makes a planet a planet.

One of those traits required a planet had to “clear” its orbit; meaning it had to provide the greatest gravitational force in its orbit.

Since the gravity of Neptune influences Pluto (and whose orbits intersect twice over one rotation of the Sun), the new IAU standards could no longer allow the Kuiper Belt object to be considered a full-fledged planet, so it was demoted to dwarf planet status.

There are some people who say that, under the new IAU definition, even our own planet, Earth, is a dwarf.

Investigators led by Philip Metzger, a planetary scientist with the Florida Space Institute at the University of Central Florida, in Orlando, Florida, claim that the reason for Pluto’s demotion was not valid.

So they went through and analyzed 200 years’ worth of scientific literature to prove their point.

After reviewing the various publications, they say only one publication, from 1802, used the “clear-orbit” requirement to classify planets and that was later found to be based on disproven reasoning.

Orbits of Saturn, Uranus, Neptune and Pluto. Notice that Pluto's orbit intersects twice with Neptune's. (Wikimedia Commons/CC BY-SA 2.5)

Orbits of Saturn, Uranus, Neptune, and Pluto. Notice that Pluto’s orbit intersects twice with Neptune’s. (Wikimedia Commons/CC BY-SA 2.5)

The researchers documented their findings in a new study that was recently published online in the journal Icarus.

“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,” says Metzger in a university press release.  “And it would leave out the second-most complex, interesting planet in our solar system,” he added.

The Florida researchers say what defines a planet should be based on its own fundamental properties, rather than variables such as the dynamics of its orbit.

What do you think?  Should Pluto be reclassified and regain its planet status?