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Facts on a Beautiful, Yet Unknown Uranian Moon

written by: Aggeliki K.•edited by: RC Davison•updated: 8/14/2011

Titania is one of the largest and most distant moons of our Solar System. Its existence arouses mystery and wonder since no specific mission has ever studied this beautiful and largest moon of Uranus and very little is known about it.

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    Titania Facts and Information

    Titania, the Largest Moon of Uranus Discovery:

    Titania of Uranus was discovered in 1787 by William Herschel, a British astronomer who also discovered the second largest moon of Uranus, Oberon. Due to the distance of the objects, his discovery was only confirmed almost fifty years later. At that time, he also claimed to have discovered other Uranian moons as well. His claims however were never confirmed at all, so he didn't get credit for discovering them.


    The moon was named after the Queen of the Fairies, a character of the famous play: "A Midsummer Night's Dream", written by William Shakespeare. The rest of Uranus' moons also took their names from characters of Shakespeare and Alexander Pope plays.

    For more information on their naming visit this article: "The Literary Moons of Uranus"


    Titania is the eighth largest moon in the Solar System. It is believed that it was formed from a gas and dust nebula that surrounded Uranus during the early stages of its life. The accretion of matter probably lasted thousands of years and the extreme impacts and stresses led to the fractured moon surface and the deep canyons. This shaping may have lasted millions of years, although little is known regarding the formation and evolution of the moon.

    Physical characteristics:

    Mass: 3.527 ± 0.09 × 1021 kg (5.908 × 10−4 Earths)

    Volume: 2,056,622,001 km3

    Mean radius: 788.9 km

    Mean density: 1.7 g/cm3

    Mean distance from Uranus: 435.84 km

    Magnitude: +13.73

    Maximum temperature: 89°K (during summer solstice)

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    Composition, Surface and Atmosphere

    Comparison Among the Five Largest Uranian Moons 

    Titania mainly consists of water ice (50%), rock (30%) and smaller amounts of methane and other heavy organic compounds (20%) This composition is quite unusual since most of the moons that belong to the outer planets are made up of ice. The interior is thought to consist of a rocky core surrounded by a water layer, like an underground sea or ocean. Its composition is similar to other Uranian moons such as Ariel, although much larger.
    Regarding its surface, the main features are the numerous small craters, long rifts and deep valleys. Some of these valleys are up to 1,500 long and their walls seem to reflect sunlight to a large degree thus contributing to Titania's brightness. Another factor that may affect its brightness is the possibility of frost deposits existing on the surface.
    Since carbon dioxide is present on the surface, there is a chance that a seasonal carbon dioxide atmosphere occurs due to temperature and pressure fluctuations. Other gases such as nitrogen and methane are less likely to exist due to the moon's low gravity.

    General Size Comparison Among the Most Important Moons of Our Solar System 

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    Orbiting Around Uranus

    Titania is the second farthest moon from Uranus with its orbit lying almost above the Uranus equator and within the planet's magnetosphere. Another important fact is that its orbital period is equal to its rotational period. This means that it always shows the same side to Uranus, similarly to the case of the Earth and the Moon. The phenomenon is called 'tidal locking' and it is common among the moons of our solar system.

    Titania experiences an extreme seasonal cycle. The poles of the moon remain for 42 years under continuous darkness and another 42 years under sunlight, and the Sun reaches the zenith over each of the poles when it is summer solstice accordingly. What's more, mutual occultations among the moons are possible to observe when the equatorial plane of Uranus intersects the Earth. The phenomenon repeats itself every 42 years.

    Orbital Characteristics:

    Orbital period: ~8.7 days

    Rotational period: ~8.7 days

    Mean orbital velocity: 3.65 km/s

    Escape velocity: 0.773 km/s

    Eccentricity: 0.0011

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    Exploration and Future Mission Potential

    Very little is known about Uranus and its moons compared to Jupiter or Saturn, since it lies so far in the outer solar system. Voyager 2 was the only mission ever to visit the Uranian system. The spacecraft passed close to Titania at a distance of 365,200 km (approximately the distance between the Earth and the Moon) in 1986 and took pictures of Uranus and the moon. During this passing, the northern hemisphere of the moon was not fully illuminated due to the winter solstice, and only 40% of the surface was finally imaged.

    The only hope for exploring this distant world more extensively, lies in the possible launching of the "Uranus orbiter and probe mission". The objective of this mission, that was suggested in 2011, is to study both the planet and its moons. The current study proposes the use of solar-electric propulsion that will allow a journey of 13 years. Launching is suggested to take place in the years 2020-2030, although the mission is currently characterized as third priority after the Mars Astrobiology mission and the Europa-Jupiter System mission.


  • Titania (Wikipedia.Org)
  • "Comparison Among the Five Largest Uranian Moons" by NASA
  • "Titania, the Largest Moon of Uranus" by NASA
  • Titania, SeaSky.Org
  • "General Size Comparison Among the Most Important Moons of Our Solar System" by NASA