PROFILEDwarf planet
A question of classification
In 2006 the International Astronomical Union defined criteria for planets and a category of dwarf planets, which includes Eris, Pluto, Ceres, Haumea and Makemake.
A moon called Dysnomia
Eris has a moon, Dysnomia. Studying its orbit helps astronomers determine the dwarf planet’s mass.
FACTS TO EXPLORE
ORBITAL PERIODabout 557 Earth years
LOCATIONTrans-Neptunian region
Values are rounded. AU means astronomical unit. NASA source ↗