Claim: Pluto has gravity.

A dwarf planet is a planetary-mass object that is neither a planet nor a natural satellite . That is , it is in direct orbit of the Sun , and is massive enough for its gravity to crush it into a hydrostatic equilibrium shape -LRB- usually a spheroid -RRB- , but has not cleared the neighborhood of other material around its orbit .   The term dwarf planet was adopted in 2006 as part of a three-way categorization of bodies orbiting the Sun , brought about by an increase in discoveries of objects farther away from the Sun than Neptune that rivaled Pluto in size , and finally precipitated by the discovery of an even more massive object , Eris . The exclusion of dwarf planets from the roster of planets by the IAU has been both praised and criticized ; it was said to be the `` right decision '' by astronomer Mike Brown , who discovered Eris and other new dwarf planets , but has been rejected by Alan Stern , who had coined the term dwarf planet in April 1991 .   The International Astronomical Union -LRB- IAU -RRB- currently recognizes five dwarf planets : ; Pluto ; ; ; and . Brown criticizes this official recognition : `` A reasonable person might think that this means that there are five known objects in the solar system which fit the IAU definition of dwarf planet , but this reasonable person would be nowhere close to correct . ''   Another hundred or so known objects in the Solar System are suspected to be dwarf planets . Estimates are that up to 200 dwarf planets will be identified when the entire region known as the Kuiper belt is explored , and that the number may exceed 10,000 when objects scattered outside the Kuiper belt are considered . Individual astronomers recognize several of these , and in August 2011 Mike Brown published a list of 390 candidate objects , ranging from `` nearly certain '' to `` possible '' dwarf planets . '' '' Brown currently identifies ten known trans-Neptunian objects -- the four accepted by the IAU plus , , , , and -- as `` virtually certain '' , with another twenty highly likely . Stern states that there are more than a dozen known dwarf planets .   Only two of these bodies , Ceres and Pluto , have been observed in enough detail to demonstrate that they actually fit the IAU 's definition . The IAU accepted Eris as a dwarf planet because it is more massive than Pluto . They subsequently decided that unnamed trans-Neptunian objects with an absolute magnitude brighter than +1 -LRB- and hence a diameter of ≥ 838 km assuming a geometric albedo of ≤ 1 -RRB- are to be named under the assumption that they are dwarf planets .   The classification of bodies in other planetary systems with the characteristics of dwarf planets has not been addressed .