When astronomers stripped Pluto of its status as a planet in 2006, children and grown-ups raised a ruckus. Some kids even sent hate mail to the Hayden Planetarium complaining about Pluto's "demotion" to dwarf planet status.
"Why do you think Pluto is no longer a planet?" Emerson York, then a third-grader living in Mansfield, Pennsylvania, wrote in a letter to the Planetarium's director, Neil deGrasse Tyson. "Pluto is my faveret planet!!! PLUTO IS A PLANET!!!!!!!"
Now it seems some astronomers are having second thoughts. In a Sept. 18 debate hosted in Cambridge, Mass. at the Harvard-Smithsonian Center for Astrophysics, three experts in planetary science duked it out over whether Pluto should be considered a planet.
Dr. Gareth Williams, associate director of the Minor Planet Center in Cambridge, said the icy body does not qualify for planetary status. But Dr. Dimitar Sasselov, director of Harvard’s Origins of Life Initiative, argued otherwise. And Dr. Owen Gingerich, professor emeritus of astronomy at Harvard and a senior astronomer emeritus at the Smithsonian Astrophysical Observatory, argued that defining what a planet is shouldn't be up to scientists.
“What is a planet is a culturally defined word that has changed over the ages. The IAU was foolhardy to try and define the word planet," he said.
Bill Nye didn't participate in the debate, but the self-described "longtime fan of Pluto" told The Huffington Post in an email:
If astronomers want to call Pluto a “planet,” that’s fine with me. If that is the route they choose, I believe they will add the several other objects way out there that have enough gravity to be spherical. ... I love Pluto as much as the next guy, but it has a different origin from the traditional planets and orbits in a different plane. It might be exciting to have names for hundreds of new (very old) planets, but I would be fine with 8 "traditionals" and hundreds of "Plutoids." These objects are out there and have the characteristics they have regardless of what we call them. But I know, people get pretty passionate about it.
Just what is a planet? According to the definition established by the International Astronomical Union (IAU), a planet is a celestial object that meets three requirements: it is round, it orbits the sun, and it has exerted gravitational dominance in its surrounding area, "clearing the neighborhood" of other bodies around its orbit.
Pluto fails to meet the last criterion, as objects similar in size to Pluto are nearby.
What do you think? Should Pluto be reinstated as a planet? Watch the debate in the video below, and then decide which team you're on in the poll underneath.