Could Pluto Regain the Title of 'Planet'?

Experts have recently decided to revisit the question "what is a planet?" citing the fact that it remains unclear if many of the hundreds of exo-planets observed in far-off solar systems are actually true planets, or just various "planetoids" or dwarf planets like Pluto was first demoted to back in 2006.

The current definition of a "planet," according to the International Astronomical Union (IAU), only truly describes the eight planets that orbit our Sun:

A planet is a celestial body that is in orbit around the Sun, is round or nearly round, and has "cleared the neighborhood" around its orbit. That last bit could be a little confusing, but it essentially means that it is the sole large celestial body stuck in its orbital track around a star.

However, what about all those exoplanets that we are constantly hearing about? They boast unusual orbits, sizes, and stars that may not always fit into the IAU's definition.

So eight years after the IAU definition was tentatively agreed upon, the Harvard-Smithsonian Center for Astrophysics decided to revisit the question in a publically held debate between three vetted experts. (You can watch the entire debate in the video below.)

According to Astrobiology Magazine, just to mix things up and ensure fairness, science historian Owen Gingerich, who chaired the 2006 IAU planet definition committee, was asked to defend the historical viewpoint that Pluto is indeed a planet. Gareth Williams, associate director of the Minor Planet Center, presented the IAU's viewpoint that Pluto no longer fits the definition; and Dimitar Sasselov, director of the Harvard Origins of Life Initiative, considered the scientific definition of "planet" while taking exoplanets into account.

Unsurprisingly, when presented with the whopping amount of new scientific data on exoplanets, an audience of public enthusiasts eagerly agreed with Sasselov that Pluto is a planet - fitting a new simplistic definition that a planet is "the smallest spherical lump of matter that formed around stars or stellar remnants."

Still, what a small public crowd and some experts think won't exactly change the opinion of the IAU. However, it does show that there is more to be considered, and there may be a real chance that Pluto could one day regain its place in the planetary echelon.

[Credit: CfA Observatory Nights]