31. By 1992, astronomers discovered more trans-Neptunian objects _ masses beyond Neptune that orbited the sun. 32. Under this new definition, Pluto and the other trans-Neptunian objects do not qualify as planets. 33. The discovery of several other trans-Neptunian objects approaching the size of Pluto, such as Eris. 34. As Neptune traveled outward, it scattered many trans-Neptunian objects into higher and more eccentric orbits. 35. Pluto was easiest to find because it has the highest apparent magnitude of all known trans-Neptunian objects. 36. Many thousands of objects of this size range have yet to be discovered in the Trans-Neptunian region. 37. Known trans-Neptunian objects are often divided into two subpopulations : the Kuiper belt and the scattered disc. 38. By 2005, three trans-Neptunian objects comparable in size to Pluto ( Eris ) had been reported. 39. "" " is a trans-Neptunian object orbiting the Sun in the scattered disc. 40. In 1900 and 1901, Harvard College Observatory director William Henry Pickering led two searches for trans-Neptunian planets.
