The detection of Eris dwarf planet detection provoked debate about Pluto’s classification as a planet. Eris is slightly larger than Pluto.
So if Pluto qualified as a full-fledged planet, then Eris certainly should too. Astronomers attending the International Astronomical Union meeting in 2006 worked to settle this dilemma. In the end, we lost a planet rather than gaining one. Pluto was demoted and reclassified as a dwarf planet along with Eris and the asteroid Ceres, the most massive member of the asteroid belt.
Eris is the biggest dwarf planet and Eris is the furthest planet from the sun.
Eris has only one moon called Dysnomia that has been discovered by scientists. Mike Brown discovered Dysnomia on September 15th 2005. Dysnomia is about 100km - 250km in diameter. Its orbit period around Eris is 14 days.
Image shown above is an artist's concept of Kuiper Belt object Eris and its tiny satellite Dysnomia. Eris is the large object at the bottom of the illustration. A portion of its surface is lit by the Sun, located in the upper left corner of the image. Eris's moon, Dysnomia, is located just above and to the left of Eris. The Hubble Space Telescope and Keck Observatory took images of Dysnomia's movement from which astronomer Mike Brown (Caltech) precisely calculated Eris to be 27 percent more massive than Pluto. Artwork Credit: NASA, ESA, Adolph Schaller (for STScI)
Source: NASA
