Titania (moon).html |
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Discovery
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| Discovered by | William Herschel |
| Discovery date | January 11, 1787 |
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Designations
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| Alternate name | Uranus III |
| Adjective | Titanian |
| Semi-major axis | 435 910 km |
| Mean orbit radius | 436 300 km |
| Eccentricity | 0.0011 |
| Orbital period | 8.706 d |
| Inclination | 0.340° (to Uranus' equator) |
| Satellite of | Uranus |
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Physical characteristics
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| Mean radius | 788.9 km (0.1237 Earths) |
| Surface area | 7 820 000 km² |
| Volume | 2 057 000 000 km³ |
| Mass | 3.526×1021 kg (5.9×10-4 Earths) |
| Mean density | 1.72 g/cm³ |
| Equatorial surface gravity | 0.378 m/s² (~0.039 g) |
| Escape velocity | 0.77 km/s |
| Rotation period | presumed synchronous |
| Axial tilt | 0 |
| Albedo | 0.27 |
| Temperature | ~60 K |
| Apparent magnitude | 13.73 |
Titania (pronounced /tɨˈtɑːnjə/ ti-TAH-nyə, also /taɪˈteɪniə/ tye-TAY-nee-ə) is the largest moon of Uranus and the eighth largest moon in the Solar System.
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Discovery
Titania was discovered on January 11, 1787 by William Herschel. He reported it and Oberon the same year.1 He later reported four more satellites, which turned out to be spurious.2
Name and pronunciation
The names of Titania and the other four satellites of Uranus then known were suggested by Herschel's son John Herschel in 1852 at the request of William Lassell, who had discovered Ariel and Umbriel the year before.3 Lassell had earlier endorsed Herschel's 1847 naming scheme for the seven then-known satellites of Saturn and had named his newly-discovered eighth satellite Hyperion in accordance with Herschel's naming scheme in 1848.
All of the moons of Uranus are named for characters from Shakespeare or Alexander Pope. Titania was named after Titania, the Queen of the Faeries in A Midsummer Night's Dream.
Shakespeare's character's name is pronounced /tɨˈtɑːnjə/, but the moon is often /taɪˈteɪniə/, by analogy with the familiar chemical element titanium. The adjectival form, Titanian, is homonymous with that of Saturn's moon Titan.
It is also called Uranus III.
Physical characteristics
So far the only close-up images of Titania are from the Voyager 2 probe, which photographed the moon during its Uranus flyby in January, 1986. At the time of the flyby the southern hemisphere of the moon was pointed towards the Sun; the northern hemisphere was unobservable.
Although its interior composition is uncertain, one model suggests that Titania is composed of roughly 50% water ice, 30% silicate rock, and 20% methane-related organic compounds. A major surface feature is a huge canyon that dwarfs the scale of the Grand Canyon on Earth and is in the same class as the Valles Marineris on Mars or Ithaca Chasma on Saturn's moon Tethys.
Scientists recognise the following geological features on Titania:
Occultation
On September 8, 2001, Titania occulted a faint star; this was an opportunity to both refine its diameter and ephemeris, and to detect any extant atmosphere. The data revealed no atmosphere to a surface pressure of 0.03 microbars; if it exists, it would have to be far thinner than that of Triton or Pluto.45
See also
Notes
- ^ Herschel, "An Account of the Discovery of Two Satellites Revolving Round the Georgian Planet", Philosophical Transactions of the Royal Society of London, Vol. 77, pp. 125-129, 1787; and "On George's Planet and its satellites", Philosophical Transactions of the Royal Society of London, Vol. 78, pp. 364-378, 1788.
- ^ "On the Discovery of Four Additional Satellites of the Georgium Sidus; The Retrograde Motion of Its Old Satellites Announced; And the Cause of Their Disappearance at Certain Distances from the Planet Explained", Philosophical Transactions of the Royal Society of London, Vol. 88, pp. 47-79, 1798.
- ^ http://adsabs.harvard.edu//full/seri/AN.../0034//0000169.000.html Adsabs.harvard.edu Retrieved on 05-19-07
- ^ http://www.obspm.fr/actual/nouvelle/mar02/titania.en.shtml Obspm.fr Retrieved on 05-19-07
- ^ http://www.lesia.obspm.fr/~titania/results.html Lesia.obspm.fr Retrieved on 05-19-07
External links
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