As of 2017, Pluto is the largest known trans-Neptunian object by volume in our solar system.
Pluto . Pluto is the largest and second-most-massive known dwarf planet in the Solar System and the ninth-largest and tenth-most-massive known object directly orbiting the Sun . It is the largest known trans-Neptunian object by volume but is less massive than Eris . Solar System . Identified dwarf planets include the asteroid Ceres and the trans-Neptunian objects Pluto and Eris .