Following the discovery, it was recognized that Pluto was not massive enough to be the expected ninth planet, and some astronomers began to consider it the first of a new class of objects. Indeed, Tombaugh searched for additional trans-Neptunian objects for years. However, due to the lack of any further discoveries, he concluded that Pluto was indeed a planet. The idea that Pluto was not a true planet remained a minority position until the discovery of other Kuiper belt objects in the late 1990s, which showed that it did not orbit alone but was at best the largest of several icy bodies in its region of space. ⁠ ⁠ After it was shown that at least one such body, dubbed Eris, was more massive than Pluto, the International Astronomical Union (IAU) reclassified Pluto on August 24, 2006, as a dwarf planet, leaving eight planets in the Solar System.⁠ ⁠ Tombaugh's widow, Patricia, stated after the IAU's decision that while he might have been disappointed with the change since he had resisted a...