You are here


December 8, 2010

Like all frontiers, the edge of our solar system has its fair share of discord, strife, and lawlessness. In fact, they're found in the most-distant objects yet discovered in the solar system: the dwarf planet Eris and its moon, Dysnomia.

Eris was discovered in early 2005, and it quickly caused a great discord among astronomers. That's because Eris is bigger than Pluto, which at the time was classified as the ninth planet. The new object was originally described as the tenth planet. But in 2006, astronomers drafted a new definition for "planet" that left out not only the new object, but Pluto, too.

Since the new object stirred up so much strife, the astronomers who discovered it thought it only fitting to name it for the Greek goddess of discord and strife: Eris. And when they found a moon, it was named for the daughter of Eris: Dysnomia, a spirit of lawlessness.

Despite its trouble-making discovery and namesake, Eris appears to have one of the brightest, cleanest surfaces in the solar system. It reflects more sunlight than any other known object except a moon of Saturn. And its white surface appears to have few dark markings.

That probably means that Eris once had a thin atmosphere of nitrogen and methane. But as Eris retreated from the Sun -- it's now at its farthest -- the atmosphere froze, coating the surface with fresh ice. The same thing is probably happening now on Pluto -- an orderly transition on the disorderly frontier.


Script by Damond Benningfield, Copyright 2010


Get Premium Audio

Listen to today's episode of StarDate on the web the same day it airs in high-quality streaming audio without any extra ads or announcements. Choose a $8 one-month pass, or listen every day for a year for just $30.