In August 2006, Pluto lost its planetary status when the International Astronomical Union officially declared Pluto a dwarf planet. For those who grew up with nine planets, not eight, the news came as a surprise.
The definition from the IAU excluded Pluto because it did not move through its orbit alone, which is a requirement of the IAU guidelines.
Kirby Runyon, a scientist from John Hopkins University, believes that Pluto should be classified as a planet and is making the case for Pluto, alongside several researchers.
According to Runyon, Pluto “has everything going on on its surface that you associate with a planet. … There’s nothing non-planet about it.”
Runyon led a group of six authors to draft a new definition of the word planet. The group consisted of Runyon, S. Alan Stern and Kelsi Singer, from Southern Research Institute in Colorado, Tod Lauer, from the National Optical Astronomy Observatory in Arizona, Will Grundy, from the Lowell Observatory in Arizona and Michael Summers from George Mason University in Virginia.
The new definition would give Pluto planetary status, since the definition will center on the qualities of the planet itself, instead of including external influences on the planet, as the IAU dictates.
Stern previously pointed out that other planets, including Earth, share their orbit with an asteroid, which should technically exclude them from being a planet under IAU guidelines.
The team’s new definition does not require approval from any specific group. In fact, the new definition has already been accepted by Planet Science Research Discoveries, an educational website created by scientists from the University of Hawaii.
The new definition will take the number of defined planets from eight to over 100.
Runyon hopes that the new definition, and inclusion of more planets, will garner interest in the subject from the public.
“I want the public to fall in love with planetary exploration as I have,” Runyon said. “It drives home the point of continued exploration.”