encounter with a random star or a member of the Sun's birth cluster that passed near the Solar System. In fiction Pluto in fiction See also Dwarf planet Mesoplanet Nemesis (hypothetical star) Planet Nine Sednoid Small Solar System body Triton Tyche (hypothetical planet) Notes References External links Nine planets, University of Arizona David Jewitt's Kuiper Belt site Large KBO page A list of the estimates of the diameters from johnstonarchive with references to the original papers Distant minor planets Neptune