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Solar System Exploration
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Margaret: Overview
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Margaret is considered an irregular moon of Uranus because of the eccentricity and inclination of its orbit, but it is the only such moon that travels in a prograde direction -- that is, in the same direction as the regular moons and the planet's rotation about its axis. Only about 20 km in diameter and very dark, it is likely an object that was captured by Uranus' gravity.

Discovery:
Margaret was discovered on 29 August 2003 by Scott S. Sheppard and David C. Jewitt with the Subaru 8.2-m reflector at the Mauna Kea Observatory on the island of Hawaii.

How Margaret Got its Name:
Originally called S/2003 U3, Margaret was named after a woman who serves Hero in William Shakespeare's play, "Much Ado About Nothing." Margaret is the lady-in-waiting for Hero and is mistaken for Hero when she entertains Borachio at Hero's window, something that causes Hero much embarrassment at her wedding to Claudio.

Moons of Uranus are named for characters in Shakespeare's plays and from Alexander Pope's "Rape of the Lock."

Just the Facts
Orbit Size (semi-major axis):  14,146,700 km
Mean Radius:  10.0 (assuming an albedo of 0.04) km
Volume:  4,189 km3
Mass:  6,294,407,419,008,210 kg
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Last Updated: 7 Mar 2011