WHO DEMOTED PLUTO?

Mike Brown, professor of planetary astronomy at Caltech in Pasadena, Calif., gets the credit for demoting the poor little planet. Brown’s team discovered a dwarf planet, Eris, in January 2005. At the time, it appeared to be larger than Pluto. If Pluto hadn’t been demoted, Brown says, hundreds of celestial objects would have to be considered planets. So Brown led the charge to reclassify Pluto — despite the fact that it cost him the chance to go down in history as a planet discoverer himself. Brown’s Twitter feed is @plutokiller. He titled his autobiography “How I Killed Pluto and Why It Had It Coming.” “I thought it was funny to talk about ‘killing Pluto’ because Pluto was god of the underworld,” Brown says. “But no one really picked up on that.”