Jan. 5 () –
This January 5 marks the 18th anniversary of the confirmation in 2005 of the discovery of Eris, observed two years earlier for the first time, and that it was presented as a possible tenth planet of the Solar System.
In principle, Eris seemed to be bigger than Plutoa discovery that sparked debate in the scientific community and ultimately led to the International Astronomical Union’s decision in 2006 to clarify the definition of a planet.
Recent observations indicate that Eris may actually be slightly smaller than Pluto. Pluto, Eris, and other similar objects are now classified as dwarf planets. They are also called plutoids in recognition of Pluto’s special place in our history.
Eris was first seen in 2003. during a Palomar Observatory survey of the outer solar system. Its discoverers were Mike Brown, professor of planetary astronomy at the California Institute of Technology; Chad Trujillo of the Gemini Observatory; and David Rabinowitz of Yale University.
The icy dwarf planet Eris takes 557 Earth years to complete a single orbit around our sun. The plane of Eris’s orbit is well outside the plane of the planets in the solar system and extends well beyond the Kuiper Belt, a zone of icy debris beyond the orbit of Neptune.
This dwarf planet is often so far from the Sun that its atmosphere collapses and freezes to the surface as an icy glaze. This coating shines brightly and reflects as much sunlight as freshly fallen snow. Scientists believe that surface temperatures vary between -217 to -243 degrees Celsius. The thin atmosphere will melt in a few hundred years as Eris gets closer to the Sun, exposing a rocky surface, which scientists believe is similar to Pluto.
Because Eris is too small to be seen clearly, scientists used its tiny moon Dysnomia to measure it. Dysnomia has a nearly circular orbit that lasts about 16 days. All the asteroids in the asteroid belt would easily fit inside Eris. However, Eris, like Pluto, is still smaller than Earth’s Moon.
Originally designated 2003 UB313 (and dubbed TV Warrior Xena by her discovery team), Eris is named after the ancient Greek goddess of discord and strife. The name is explained as Eris remains at the center of a scientific debate about the definition of a planet.
