It’s official. Pluto has resigned from the solar system. Citing the recent vote by the International Astronomical Union to change its status from planet to dwarf planet, the former ninth rock from the sun has responded with a firm “Thanks, but no thanks.” First, a committee of astronomers came up with a new definition that would have seen Pluto demoted from full planetary status to a subcategory called “plutons.” Then the full membership rejected that compromise and made it clear that Pluto wasn’t a real planet. “Nice try,” said the fiery ice ball. “But it’s rather condescending, don’t you think?…