Oct 11

Faraway Eris is Pluto's Twin — Dwarf planet sized up accurately as it blocks light of faint star

Source: ESO Science Release eso1142

Artist's impression of Eris and its moon Dysnomia.
Image credits: ESO/L. Calçada.

Astronomers have accurately measured the diameter of the faraway dwarf planet Eris for the first time by catching it as it passed in front of a faint star. This event was seen at the end of 2010 by telescopes in Chile, including the Belgian TRAPPIST telescope at ESO’s La Silla Observatory. The observations show that Eris is an almost perfect twin of Pluto in size. Eris appears to have a very reflective surface, suggesting that it is uniformly covered in a thin layer of ice, probably a frozen atmosphere. The results will be published in the 27 October 2011 issue of the journal Nature. (read more)

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