A Death in the Solar System

摘要

It's official. Pluto is not a red-blooded planet. As decreed in August by a vote of the General Assembly of the International Astronomical Union, Pluto is now a dwarf. At first, the IAU seemed ready to defend Pluto. On August 16, the union's seven-member Planet Definition Committee released a draft Planet Definition Resolution, which stated that round objects in orbit around the sun are planets. Pluto is a round object in orbit around the sun. Therefore, Pluto is a planet. This definition would have given everyone the right to utter "Pluto" and "Jupiter" in the same breath, even though Jupiter is 250,000 times larger. The draft resolution would also have opened the door to granting planet status to at least three objects that had, until recently, been considered unworthy.