Chilean telescopes reveal mysteries of distant dwarf planet

The new images provide unprecedented data about Pluto’s twin, Eris, which was first identified in 2005.


Amateur and professional astronomers in Chile’s northern Atacama Desert have captured unmatched images of Eris, a dwarf planet that is remarkably similar to Pluto.

The Chilean scientists, based at the European Southern Observatory’s La Silla Observatory and two amateur observatories in San Pedro de Atacama, obtained the data by tracking Eris as it passed in front of a faint star in a process known as occultation.

It is the first time that astronomers have managed to gather accurate information about the distant body, which was originally discovered in 2005.

Scientists attempted to observe the occultation process from 26 locations around the world by tracking the predicted path of the dwarf planet’s shadow, but the Chilean sites were the only ones able to provide clear images.

The observations reveal that Eris is almost exactly the same size as Pluto and has a highly reflective surface, suggesting that the dwarf planet is covered by a thin ice cap and enveloped by a frozen atmosphere.

When combined, the images recorded from Chile also demonstrate that Eris has a near perfect spherical form.

The project that was set up to capture the occultation of Eris was painstakingly planned by a team of astronomers from several universities in a number of countries including France, Belgium, Spain and Brazil.

“Observing the occultations of small bodies beyond Neptune in the Solar System requires great precision and very careful planning,” study author, Bruno Sicardy, said in a statement. “This is the best way of measuring the size of Eris without actually going there.”

The discovery of Eris six years ago was one of the key factors that led to the creation of dwarf planets as a new class of space bodies. It also prompted the reclassification of Pluto, from a planet to a dwarf planet, in 2006.

Eris is located about three times farther away from the sun than Pluto and its next occultation is due to occur in 2013.