Make Pluto a planet again!
A scientific campaign has been launched to restore Pluto to planethood. Once the solar system’s ninth planet, tiny Pluto was demoted to “dwarf planet” status in 2006 after the International Astronomical Union redefined planets as round celestial bodies that circle the sun and have “cleared their neighborhoods”—that is, become the gravitationally dominant bodies in their orbit. Because Pluto is surrounded by icy debris, it lost its full planetary status. Now two scientists involved in NASA’s New Horizons mission to explore Pluto and the Kuiper Belt, Alan Stern and David Grinspoon, are pushing for Pluto to be let back into the club. The pair argues in a Washington Post op-ed that the IAU’s definition is deeply flawed. Earth could not have been classified as a planet for its first 500 million years, they note, because back then it, too, orbited among a field of debris. Stern and Grinspoon want the IAU to adopt a simpler definition of a planet: a round object in space that is smaller than a star. If they succeed, Pluto could once again be called a planet.