In 2005 Brown discovered such an object, now called Eris, which is slightly larger than Pluto. This was an occasion for celebration, of course, but it also heralded a period of intense controvery and rivalry, which culminated in the demotion of Pluto to become one of a number of "dwarf planets". Brown tells this story in an engaging style. The science is interspersed with autobiographical information concerning his marrriage and the birth of his daughter, with whom he is clearly besotted and whose exploits occupy rather more space than perhaps they should.
This was not the first such discovery that Brown and his team had made. Earlier they had found two other, smaller, objects, one of which Brown had nicknamed Santa because it was found just before Christmas. He didn't announce the existence of either object because he wanted to have more details to publish, But before he could do so the discovery of Santa was announced by a Spanish astronomer, Jose Ortiz. Although naturally chagrined, Brown congratulated Ortiz. But later evidence emerged that strongly suggested Ortiz had obtained the coordinates of Santa from the database of the observatory where Brown's work had been done. Brown therefore had to make an immediate announcement of his own, since it would be easy for Ortiz to use the same data to "discover" Eris.
Since Eris is larger than Pluto it would logically be necessary to call it a planet. But Brown insisted, against his own interest, that there was no good scientific reason to regard either object, or any others of the kind that may be discovered in the future, as planets. The demotion of Pluto was finally decided by a committee of the International Astronomical Union in a contentious meeting.
Both Brown and the Spanish astronomers submitted names for the dwarf planet which Brown had provisionally called Santa. The IAU accepted Brown's proposal of Haumea. This implicitly meant that they endorsed Brown's claim of "unseemly behaviour" on the part of the Spanish group, but that was as far as they were prepared to go. They list Haumea but its discover's name is left blank.