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| image = | caption = ''Voyager 2'' image of Titania's southern hemisphere | discovery = yes | discoverer = William Herschel | discovered = January 11, 1787〔 | semimajor = 〔 | eccentricity = 〔 | period = 〔 | avg_speed = 3.64 km/s | inclination = (to Uranus's equator)〔 | satellite_of = Uranus | physical_characteristics = yes | mean_radius = ()〔 | surface_area = | volume = | mass = ()〔 | density = 〔 | surface_grav = m/s² | escape_velocity = km/s. }} | rotation = presumed synchronous〔 | albedo = | magnitude = 13.9〔 | temp_name1 = solstice〔 | mean_temp_1 = K | max_temp_1 = 89 K | min_temp_1 = 60 K | atmosphere = yes | atmosphere_composition = | surface_pressure = <10–20 nbar | note = no }} Titania is the largest of the moons of Uranus and the eighth largest moon in the Solar System at a diameter of . Discovered by William Herschel in 1787, Titania is named after the queen of the fairies in Shakespeare's ''A Midsummer Night's Dream''. Its orbit lies inside Uranus's magnetosphere. Titania consists of approximately equal amounts of ice and rock, and is probably differentiated into a rocky core and an icy mantle. A layer of liquid water may be present at the core–mantle boundary. The surface of Titania, which is relatively dark and slightly red in color, appears to have been shaped by both impacts and endogenic processes. It is covered with numerous impact craters reaching up to in diameter, but is less heavily cratered than the surface of Uranus's outermost moon, Oberon. Titania probably underwent an early endogenic resurfacing event which obliterated its older, heavily cratered surface. Titania's surface is cut by a system of enormous canyons and scarps, the result of the expansion of its interior during the later stages of its evolution. Like all major moons of Uranus, Titania probably formed from an accretion disk which surrounded the planet just after its formation. Infrared spectroscopy conducted from 2001 to 2005 revealed the presence of water ice as well as frozen carbon dioxide on the surface of Titania, which in turn suggested that the moon may have a tenuous carbon dioxide atmosphere with a surface pressure of about one 10 trillionth of a bar. Measurements during Titania's occultation of a star put an upper limit on the surface pressure of any possible atmosphere at 10–20 nbar. The Uranian system has been studied up close only once, by the spacecraft ''Voyager 2'' in January 1986. It took several images of Titania, which allowed mapping of about 40% of its surface. == History == Titania was discovered by William Herschel on January 11, 1787, the same day he discovered Uranus's second largest moon, Oberon.〔〔 He later reported the discoveries of four more satellites,〔 although they were subsequently revealed as spurious.〔 For nearly fifty years following their discovery, Titania and Oberon would not be observed by any instrument other than William Herschel's,〔 although the moon can be seen from Earth with a present-day high-end amateur telescope.〔 All of Uranus's moons are named after characters created by William Shakespeare or Alexander Pope. The name Titania was taken from the Queen of the Fairies in ''A Midsummer Night's Dream''.〔 The names of all four satellites of Uranus then known were suggested by Herschel's son John in 1852, at the request of William Lassell,〔 who had discovered the other two moons, Ariel and Umbriel, the year before.〔 Titania was initially referred to as "the first satellite of Uranus", and in 1848 was given the designation by William Lassell,〔 although he sometimes used William Herschel's numbering (where Titania and Oberon are II and IV).〔 In 1851 Lassell eventually numbered all four known satellites in order of their distance from the planet by Roman numerals, and since then Titania has been designated .〔 Shakespeare's character's name is pronounced , but the moon is often pronounced , by analogy with the familiar chemical element titanium.〔 The adjectival form, ''Titanian,'' is homonymous with that of Saturn's moon Titan. The name ''Titania'' is ancient Greek in origin, meaning "Daughter of the Titans." 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Titania (moon)」の詳細全文を読む スポンサード リンク
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