Eight years after it was kicked out of the planetary big boys' club, Pluto is still going through an identity crisis, as the scientific community is still in a heated debate over its status as a dwarf planet.
But Pluto could possibly be re-classified with a planetary status once again, if the folks over at the International Astronomical Union (IAU), which is in charge of classifying the heavenly bodies, heed the results of a vote by the general public that says Pluto is a planet. The vote was held at Harvard-Smithsonian Center for Astrophysics, where three planetary scientists held a discussion on the classification of Pluto.
Owen Gingerich, a former chair of the IAU planet definition committee, takes the historical viewpoint and says that "a planet is a culturally defined word that changes over time." His view is countered by Gareth Williams, associate director at the Minor Planet Center, who defended the IAU's decision to reclassify Pluto as a dwarf planet based on three criteria.
For a celestial body to be considered a planet, it should orbit around the sun, should be round or near-round in shape, and should be the largest object within its neighborhood and must not be anywhere near another body of similar size and shape. Pluto meets the first two qualifications but fails to satisfy the third as several other dwarf planets lurk just an astronomical stone's throw away.
Pluto was first classified as a planet in 1930, but skeptics surfaced in the 1970s pointing out to the existence of bigger planets in Pluto's surroundings. Eris, the biggest dwarf planet in our solar system, is 27 percent larger than Pluto, which has a radius of only 750 miles, or just one-fifth of the radius of the Earth.
Dimitar Sasselov, director of the Harvard Origins of Live Initiative, defines a planet as "the smallest, spherical lump of matter that formed around stars or stellar remnants." By this definition, Pluto is definitely a planet.
After the discussion, the audience weighed in with their opinions and agreed with Sasselov's definition. Of course, the public vote does not officially count for the IAU to initiate a reclassification of Pluto, and only planetary scientists can call upon the international body to revisit Pluto's status.
"There are currently no requests from any astronomers to put this issue on the agenda at the General Assembly," says IAU press officer Lars Lindberg Christensen in a statement emailed to USA Today.