Overlapping the Kuiper belt but extending much further outwards is the scattered disc. Scattered disc objects are believed to have been originally native to the Kuiper belt, but were ejected into erratic orbits in the outer fringes by the gravitational influence of Neptune's outward migration (see Formation and evolution of the Solar System). Most scattered disc objects have perihelia within the Kuiper belt but aphelia as far as 150 AU from the Sun. Their orbits are also highly inclined to the ecliptic plane, and are often almost perpendicular to it. Some astronomers, such as Kuiper belt co-discoverer David Jewitt, consider the scattered disc to be merely another region of the Kuiper belt, and describe scattered disc objects as "scattered Kuiper belt objects."[36] Centaurs, which roughly extend from 9 to 30 AU, are icy comet-like bodies that orbit in the region between Jupiter and Neptune. The largest known Centaur, 10199 Chariklo, has a diameter of between 200 and 250 km.[37] The first centaur to be discovered, 2060 Chiron, has been called a comet since it has been shown to develop a coma just as comets do when they approach the sun.[38] Some asronomers class Centaurs as scattered Kuiper belt objects along with the residents of the scattered disc; merely Kuiper belt objects scattered inward, rather than outward.[39] Eris Eris and its moon DysnomiaEris (68 AU average) is the largest known scattered disc object and was the cause of the most recent debate about what constitutes a planet since it is at least 5% larger than Pluto with an estimated diameter of 2400 km (1500 mi). It is now the largest of the known dwarf planets.[40] It has one moon, Dysnomia. The object has many similarities with Pluto: its orbit is highly eccentric, with a perihelion of 38.2 AU (roughly Pluto's distance from the Sun) and an aphelion of 97.6 AU, and is steeply inclined to the ecliptic plane, at 44 degrees, more so than any known object in the solar system except the newly-discovered object 2004 XR190 (also known as "Buffy"[41]) and is believed to consist largely of rock and ice.[42]