Eris, the 'planet of discord' that demoted Pluto is smaller than thought

An international team of astronomers has studied the dwarf planet Eris step ahead of a star and its size has been measured more accurately than ever , with measurements greatly reduce their volume and become, if not an object smaller than Pluto, If one of equal size. Eris was discovered in 2005 and the first calculations indicated that exceeded the size of Pluto , which contributed to the International Astronomical Union ceased to consider the latter as a planet . Although initially there was talk of tenth planet, finally won a redefinition of the concept that did not include Pluto and Eris as Astronomical Union decided that both will become part of a new category of objects, dwarf planets , reducing the number of planets in the solar system to eight.


In this new work, published in Nature , involved researchers from different Spanish hospitals, including the National Research Council (CSIC). Jose Luis Ortiz, CSIC researcher at the Institute of Astrophysics of Andalusia, has detailed the new data represent a "surprise" to reduce the estimated radius about 1163 kilometers Eris. This figure is well below previous estimates as ranged from 1,200 to 1,400 miles and made ​​it the largest object in the trans-Neptunian objects Belt, a region beyond Neptune populated rocky and icy bodies. It now appears that Pluto, with a radius of between 1,150 and 1,200 kilometers, could recover the position as the largest object in this region , according to a note of the CSIC. "However, this is difficult to pin down, since Pluto has an atmosphere that interferes with the diameter measurements," he pointed Ortiz. The study also determined that Eris albedo (the fraction of reflected light with respect to the incident ) is at least 90%, making it one of the most intrinsically bright object in the solar system (only some of Saturn's moons reflect more light percentage of Eris). Its mass and density, larger than Pluto, suggest that a body is mostly little rocky and covered with a layer of ice, the researchers of this study. The essential job results have been obtained from two telescopes the Observatory of San Pedro de Atacama in Chile, and from Trappist, the La Silla Observatory, also in Chile. At present there are five dwarf planets accepted as such , but there are several whose classification is being proposed, and also expected In the future many more will be discovered, the figure could reach hundreds and even has detailed Ortiz. Eris was allegedly the largest dwarf planet, that is, "was the king of the dwarf planets, but Pluto with our results could be a little bigger," said Ortiz.