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Faraway dwarf planet Eris is Pluto's twin in size

October 27, 2011 - London

Astronomers have found that the faraway dwarf planet Eris is an almost perfect twin of Pluto in size.

They came to the conclusion after they accurately measured the diameter of the faraway dwarf planet for the first time by catching it as it passed in front of a faint star- an event called an occultation.

This event was seen at the end of 2010 by telescopes in Chile, including the Belgian TRAPPIST telescope at ESO's La Silla Observatory.

Eris appears to have a very reflective surface, suggesting that it is uniformly covered in a thin layer of ice, probably a frozen atmosphere, according to the astronomers.

The observations were carefully planned and carried out by a team of astronomers from a number of (mainly French, Belgian, Spanish and Brazilian) universities.

While earlier observations using other methods suggested that Eris was probably about 25percent larger than Pluto with an estimated diameter of 3000 kilometres, the new study proves that the two objects are essentially the same size.

Eris's newly determined diameter stands at 2326 kilometres, with an accuracy of 12 kilometres.

This makes its size better known than that of its closer counterpart Pluto, which has a diameter estimated to be between 2300 and 2400 kilometres.

The results will be published in the latest issue of the journal Nature.


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