what is eris
Eris (minor-planet designation 136199 Eris) is the most-massive and second-largest dwarf planet known in the Solar System.t was measured to be 2,326 Â± 12 kilometers (1,445.3 Â± 7.5 mi) in diameter. Eris is 27% more massive than dwarf planet Pluto, though Pluto is slightly larger by volume. Eris's mass is about 0.27% of the Earth 's mass.