Eris

[Christopher K.]

The frigid object (temperatures range from -217°C to 243°C) whose discovery prompted Pluto's "demotion" at the 2006 IAU meeting was measured in 2007. Using Hubble and Keck information, Mike Brown determined that Eris is over a quarter larger than Pluto.

Originally known as 2003 UB313, Eris was named after a Greek goddess (what a surprise). Eris' daughter Dysnomia has her name attached to Eris' tiny satellite. Dysnomia takes about sixteen Earth days to orbit Eris. The 2006 IAU meeting also placed Eris, Pluto and Ceres into the newly-created "dwarf planet" category.

Eris will be at opposition on 15 October of this year. It takes 557 Earth years to orbit the Sun, meaning that it will not return to the place in its orbit where Mike Brown, Chad Trujillo and David Rabinowitz found it until the year 2563.

More information at:
http://www.nasa.gov/mission_pages/hubble/news/eris.html
http://www.nasa.gov/vision/universe/sol ... 60914.html
http://solarsystem.nasa.gov/planets/pro ... t=Dwa_Eris

[Christopher K.]

Observations published in October 2011 suggest Eris (minor planet 136199) is actually the same size or smaller than Pluto. Eris is also classified as a Scattered Disk object. The Scattered Disk is populated by objects just beyond Neptune with highly eccentric orbits.

Eris in the constellation Cetus the Whale and will remain there until the first half of 2037 when it crosses into Pisces.

[Christopher K.]

In recent months a 3D model of Eris has been released by NASA VTAD. Other models are available are well. (Still no sign of the possible Neptune-sized object that may be in the Kuiper Belt with Eris.)

More information:
https://solarsystem.nasa.gov/resources/ ... -3d-model/