When the International Astronomical Union got together in 2006 and updated the criteria for classification as a planet, thereby downgrading Pluto from "planet" to the informal title of "not a planet," many inside and outside the scientific community were upset. The California State Assembly actually half-seriously passed a resolution denouncing the IAU for "scientific heresy."

By the 2006 IAU standards, Pluto officially became a dwarf planet; its confidence was shot and the outer edge of our solar system became a much more solemn place. In the wake of the monumental decision, planetary models had to be torn from the ceilings of classrooms, and middle school science students across the country didn't know what they could believe in anymore.

Here's what the IAU claimed we should believe: in order to be a planet, a celestial body must meet three criteria. It must orbit around the Sun, be round or nearly round, and must have "cleared the neighborhood" around its orbit -- meaning it must have a field of gravity dominant enough to have absorbed other major objects in its orbital vicinity.

But in America, democracy reigns, and last week the Harvard-Smithsonian Center for Astrophysics re-addressed the debate, putting Pluto's planetary status to a vote once again. A debate preceded the vote, with three planetary experts offering differing points of view.

Science historian Dr. Owen Gingerich, who originally chaired the IAU planet definition committee, argued the term planet is a culturally defined term not a strictly scientific one, and that history had spoken -- Pluto is a planet. Dr. Gareth Williams, associate director of the Minor Planet Center, defended the IAU definition. Dr. Dimitar Sasselov, director of the Harvard Origins of Life Initiative, also argued that Pluto is a planet, presenting the so-called exoplanet scientist's viewpoint. He defined -- as the Smithsonian reported -- a planet as "the smallest spherical lump of matter that formed around stars or stellar remnants."

Once the debate ended, a public vote was recorded and Sasselov turned out to be the most convincing. Audience members decided that Pluto is indeed a planet. It's not yet clear whether the IAU will take the unofficial opinions of everyday science fans into consideration.