Get Ready to Welcome Pluto Back as a Planet

Vanderbilt astronomer David Weintraub thinks Pluto was wrongly kicked out of the planet club in 2006. But he's confident that this is going to be a very big year for Pluto and for another so-called "dwarf planet" named Ceres, he writes in the Conversation. NASA spacecraft will visit Ceres in March and Pluto in July, and Weintraub thinks two promotions will follow. "I expect 2015 will be the year when general consensus, built upon our new knowledge of these two objects, will return Pluto and add Ceres to our family of solar system planets."

Both are "spheroidal objects" and both orbit the sun, two key parts of the definition of a planet, he writes. The International Astronomical Union demoted Pluto because it has not "cleared its neighborhood," or become the dominant object in its orbit, and Weintraub finds the notion poorly defined and understood. He also notes that the IAU vote against Pluto was 237-157, with about 9,500 members not present at the assembly. All that will be ancient history when Pluto and Ceres begin revealing their secrets and proving their rightful status. "Get ready to party," he concludes. "Ceres and Pluto are coming home." Click for the full post. (More Pluto stories.)