Dwarf planets get names and numbers
The trouble-making object that forced astronomers to reconsider Pluto's planetary status has finally received its official name - Eris.

The name, taken from a Greek goddess of discord and strife, was "too perfect to resist," says Eris discoverer Michael Brown of Caltech. It was the January 2005 discovery of Eris - better known by its TV-inspired nickname, Xena - that put Pluto's demotion on a fast track. Eris is about 5-percent bigger than Pluto.

More, from Astronomy.com: Dwarf planets get new names
Astronomers give "Xena" a permanent name and add Pluto to a catalog of small bodies.
Francis Reddy/for Astronomy.com.

[The International Astronomical Union (IAU) put a hold on naming Eris until scientists could define what a planet is — and determine whether both objects or neither qualified. Following contentious discussions, the world's astronomers voted August 24 to classify both objects as "dwarf planets."]