Astronomy

Demoted from planet’s family to dwarf planet isn’t enough for Pluto. Last week astronomers announce new data showing that the dwarf planet Eris is 27 percent more massive than Pluto. According to Mike Brown, the discoverer of Eris, and his graduate student Emily Schaller, the data confirm that Eris weighs 16.6 billion trillion kilograms. They know this because of the time it takes Eris’ moon, Dysnomia, to complete an orbit.

This was Pluto’s last chance to be the biggest thing found so far in the Kuiper belt. There was a possibility that Pluto and Eris were roughly the same size, but these new results show that it’s second place at best for Pluto.

Eris was discovered in 2005 with Palomar Observatory’s 48-inch Samuel Oschin Telescope, an instrument specially adapted to do comprehensive searches for objects in the sky.

When it became apparent that Eris was similar in size if not larger than Pluto, Brown and others called for the International Astronomical Union to rule on its planetary status. The end result was demotion of Pluto and the redefinition of it and other Kuiper-belt objects as dwarf planets.

The new results, obtained with Hubble Space Telescope and Keck Observatory data, indicate that the density of the material making up Eris is about two grams per cubic centimeter. This means that Eris likely is made up of ice and rock, and thus is similar in composition to Pluto. Past results from the Hubble Space Telescope had already allowed planetary scientists to determine that its diameter is 2,400 kilometers, also larger than Pluto’s.

Of course, this result will disappoint people who had concern to Pluto’s planetary status. But that’s science. New discoveries comes time to time. As new discovery arrive, old concept will suddenly changed with the new one.

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