Makemake. Eris. Ceres. Pluto. Dwarf planet. Pluto in approximate true colour based on Hubble Space Telescope albedo data A dwarf planet is an object the size of a planet (a planetary-mass object) but that is neither a planet nor a moon or other natural satellite.
More explicitly, the International Astronomical Union (IAU) defines a dwarf planet as a celestial body in direct orbit of the Sun[1] that is massive enough for its shape to be controlled by gravity, but that unlike a planet has not cleared its orbit of other objects.[2][3] Dwarf Planets. Dwarf Planets: List of Dwarf Planets. Planets: The planet count in our solar system has gone as high as 15 before new discoveries prompted a fine tuning of the definition of a planet.
The most recent change was in 2006 when scientists reclassified Pluto as a new kind of object - a dwarf planet.