Study Guide - Uranus  
                   and its Moons and Rings
 

Mythology of Uranus (more)

Discovered in 1781 by Sir William Herschel (telescope)
         (more) (more) (more) (more) (Museum)
    Uranus originally named "Georgium Sidus" by Herschel after
          King George III of England. Others called it "Herschel"!
    Name Uranus proposed by Johannn E. Bode later accepted by
          the world around 1850

Basic Properties:

    Distance from Sun = 19.2 AU
    Prev = 84.1 yrs.
    Prot = 17h 14min.
    Radius = 4.1 Earths
    Mass = 14.54 Earths
    Density = 1.3 g/cm3
    Gravity = 0.8 Earth
    Axial tilt = 98 degrees

Rotation considered retrograde
Uranian rotational axis roughly in the ecliptic plane

Atmosphere (pic) (pic)

    High level photochemical haze/no detail in visible
        surface features
    Dark polar cap; mid-latitude brightening
    Clouds/methane ice crystals/ east-west circulation
    Seasons on Uranus (pic)

Interior

    Infrared emission temperature of 58 K
    No evidence of large internal heat source but
        atmospheric movements indicate something is
        happening inside planet
   Interior rotates more slowly than the atmosphere
        (from radio bursts/magnetic field rotation studies)

Magnetosphere (more) (more) (pic) 

   Magnetic field = 0.74 Earth
    Tilt of magnetic axis = -59 degrees
    Center of the field is offset from the planet's center
    Aurora is present (anim.) 
    Electroglow (UV) - indicates presence
        of a magnetic field

Uranian Satellites     

    Five large moons (memory device: MAUTO)
    Sizes ranging from 235 to 760 km in radius and have
        an average albedo of 30 percent (lower than the
        Saturnian moons)
    Mixtures of ice and rock, all cratered
    Names are from William Shakespeare's "A Midsummer's
        Night Dream" (Titania, Oberon , Miranda) and
        Alexander Pope's "Rape of the Lock" (Ariel, Umbriel)

    Ariel: youngest surface/tectonic activity/few large craters,
        global fractures/fault valleys
    Umbriel: darker, uniform surface covered with craters,
        unexplained bright ring feature
    Titania: few large craters, many young scarps, some
        fresh material, trenches
    Oberon: many large craters (e.g., Hamlet), high mountain,
        scarps, dark patches in crater floors
    Miranda: part of surface has undulating cratered plains,
        part with regions of scarps that show as dark bands,
        global faults; chevron feature; racetrack features.

   Other small moons
        Albedos: 5-7 percent for smallest 10 moons/ largest one,
           Puck (more), is only 75km in radius

Uranian Rings   (more) (pic) (pic) (pics) (stats)

    Discovered in 1977 during a stellar occultation
        by James Elliot and colleagues from the KAO (more)
    Nine rings known now from ground based observations
    Epsilon ring the widest and easiest seen and bracketed
        by "shepherd" moons
    Very narrow (few kms)
    Little dust in rings
    Rings consist of dark particles several cm across
    Rings 1986 U1R (lambda) and 1986 U2R discovered
        by Voyager 2 (pics)

Mission to Uranus

    Voyager 2 encounter (1986)

Other Interesting Sites

    Folger Shakespeare Library - First Folio Online (and more) 
    Exploring the Planets - Air & Space Museum
    Welcome to the Planets site - Uranus
   The Jet Propulsion Laboratory (JPL)
        JPL Solar System Site - Uranus
    Voyager -Uranus info
    Solar System Exploration Site (SSE)
    Stories of Our Solar System site - Uranus
    Britannica (via space.com) - Uranus

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Last Updated:  Nov.18, 2007 by Dr. S. J. Daunt

Department of Physics & Astronomy