Monday, July 27, 2009

Dysnomia:Moon of Eris


 Eris I Dysnomia, is the only known moon of the dwarf planet Eris. It was discovered in 2005 by Mike Brown and the laser guide star adaptive optics team at the W. M. Keck Observatory, and carried the provisional designation of S/2005 (2003 UB313) 1 until officially named Dysnomia (from the Ancient Greek word Δυσνομία meaning "lawlessness") after the daughter of the Greek goddess Eris.
Dysnomia is about 500 times fainter than Eris, and its diameter is estimated to be 100 to 250 km. The moon is likely too small to be spherical due to self gravity. Combining Keck and Hubble observations, the satellite was used to constrain the mass of Eris, and orbital parameters were estimated. Its orbital period is calculated to be 15.774±0.002 d.These observations indicate that Dysnomia orbits Eris at a distance of 37 370 ± 150 km. This suggests that the mass of the system is approximately 1.27 times that of Pluto.

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