OUR SOLAR SYSTEM turns out to be a whole lot messier than we once thought.
For generations, schoolchildren were taught that the sun had precisely nine planets revolving around it. Anyone who could memorize the phrase “My Very Educated Mother Just Showed Us Nine Planets ” could (maybe) remember their names.
But reality is more complex. And this week, a committee of the International Astronomical Union defined “planet” in a way that would take in three more heavenly bodies. Earthlings, meet Ceres, Charon, and Xena.
According to the panel, a planet is any spherical object that orbits the sun and has a diameter of roughly 250 to 500 miles or larger. If the astronomical union adopts that proposal, it’s bound to cause a stir in the general public. Being told that there are 12 planets in the solar system rather than nine is like finding out that your own home has a few more rooms that you’d somehow overlooked. Once you get past the cognitive dissonance, it’s interesting to contemplate what you might do with all the extra space. … in the last several years, astronomers have discovered plenty of new real estate in the outskirts of the solar system.
One such object is Xena, first observed in 2003 and named unofficially for the television character played by Lucy Lawless. (Let’s hope that the name sticks.) Under the committee’s new definition, it supplants Pluto as the most distant planet in the solar system. – boston