Astronomers Michael Brown, Chad Trujillo, and David Rabinowitz working from the Palomar Observatory discovered the dwarf planet Eris on 5th January 2005. The discovery was made on the basis of photos taken in 2003. At a later date, observations from the W. M. Keck Observatory found that the planet has a moon (Dysnomia).
The discovery of Eris was announced on 29th June 2005. It is now the second largest known dwarf planet.
