60-Second Science

Pluto Was Never As Planetary As Eris

New studies show that the dwarf planet Eris is actually bigger than Pluto, which was recently demoted from full planet down to dwarf planet status. David Biello reports.

It’s been a tough year for Pluto. Last summer, astronomers demoted the icy sphere to dwarf planet status. Now the dwarf planet formerly known as Xena has displaced Pluto as the largest such object known.  That’s according to a report in the journal Science. Named after Eris, the goddess of strife, the icy usurper proved to be 27 percent more massive than Pluto when examined by astronomer Mike Brown of the California Institute of Technology, who also discovered Eris. He used the Hubble Space Telescope and Keck Observatory as well as the orbital period of Eris's moon Dysnomia to determine the density of what is now the queen of the dwarf planets. She weighs in at 16.6 billion trillion kilograms and has a girth of 2,400 kilometers--making her the pudgier of the two dwarves. Pluto doesn't even have the most eccentric orbit in the Kuiper Belt anymore. But at least Pluto will always have the 76 glorious years it was officially classified as the ninth planet.  With Pluto out, the planetary mnemonic I learned as a child has been changed to: My Very Excellent Mother Just Sent Us…Nothing. 

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