Margaret (moon)
Template:Short description Template:Infobox planet
Margaret is the only known prograde irregular satellite of the moons of Uranus. It was discovered by Scott S. Sheppard, et al. in 2003 and given the provisional designation S/2003 U 3.<ref name="iauc8217" />
Confirmed as Uranus XXIII, it was named after the servant of Hero in William Shakespeare's play Much Ado About Nothing.<ref name="usgs" /> The name was also chosen to match the name of Sheppard's mother.<ref name=podcast>Template:Cite web</ref>
Orbit
Margaret stands out as the only known prograde irregular satellite of Uranus. The diagram illustrates the orbital parameters of Margaret, unique among the irregular satellites of Uranus, with inclination on the vertical axis and the eccentricity of the orbits represented by the segments extending from the pericentre to the apocentre.
Margaret's inclination of 57° is close to the limit of stability. The intermediate inclinations 60 < i < 140 are devoid of known moons due to the Kozai instability.Template:Sfn In this instability region, solar perturbations at apoapse cause the moons in this region to acquire large eccentricities that lead to collisions or ejection over 10 million to a billion years. Margaret's periapsis precession period (Pw) is almost 1.6 million years long.<ref name="JPL" /> Margaret itself may be ejected from the Uranian system in the far future.<ref name=Margaret>Template:Cite journal</ref>
Margaret's orbit is subject to solar and planetary perturbations; thus, its orbital elements are variable over short timescales. Over a timescale of 8,000 years, the average orbital eccentricity of Margaret is 0.68. In 2010, its eccentricity grew to 0.81,<ref name="IAU-MPC nses" /> temporarily giving Margaret the most eccentric orbit of any known moon in the Solar System, though Nereid's average eccentricity of 0.75 is greater.<ref name="JPL" /> Template:Clear left
See also
References
External links
- Margaret Profile by NASA's Solar System Exploration
- David Jewitt pages
- Uranus' Known Satellites (by Scott S. Sheppard)
- Ephemeris IAU-NSES
Template:Navbox Template:Uranus Template:Solar System moons (compact)