Dwarf planet to gradually become tidally locked, such that it always presents the same face to its companion. An extreme example of this is the Pluto–Charon system, where both bodies are tidally locked to each other. Earth's Moon is also tidally locked, as are many satellites of the gas giants. The upper and lower size and mass limits of dwarf planets have not been specified by the IAU. There is no defined upper limit, and an object larger or more massive than Mercury that has not "cleared the neighbourhood around its orbit" would be classified as a dwarf planet. The lower limit
IAU definition of planet Pluto would have been the prototype for this class. The term "dwarf planet" would have been available to describe all planets smaller than the eight "classical planets" in orbit around the Sun, though would not have been an official IAU classification. The IAU did not make recommendations in the draft resolution on what separated a planet from a brown dwarf. A vote on the proposal was scheduled for August 24, 2006. Such a definition of the term "planet" could also have led to changes in classification for the trans-Neptunian objects , , Sedna, Orcus, Quaoar, Varuna, , Ixion, and ,