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Moon of Uranus
Titania
Queen of the fairies and the biggest moon of Uranus, cut by canyons 1,500 km long
Key facts
- Diameter
- About 982 miles / 1,580 km (NASA rounds to roughly 1,600 km)
- Distance from Uranus
- About 271,000 miles / 436,000 km
- One orbit
- About 8.7 Earth days
- Size rank
- Largest moon of Uranus; eighth-largest moon in the solar system
- Discovered
- 11 January 1787, by William Herschel
- Named after
- Titania, queen of the fairies in Shakespeare's A Midsummer Night's Dream
- Surface
- Grey, cratered ice and rock, cut by huge fault valleys with bright frost
- Longest valley
- Messina Chasma, about 932 miles / 1,500 km
- Average temperature
- About minus 200 °C (about 70 K)
- Density
- About 1.65 g/cm³, roughly half ice and half rock
- Moons of Uranus
- 29 known, as of August 2026
- Visited by
- Voyager 2 only, 24 January 1986, passing about 227,000 miles / 365,000 km away
About Titania
Titania is a moon. It goes round the planet Uranus. It is the biggest moon Uranus has. Titania is made of ice and rock. It is grey and very cold. Huge cracks run across its surface. Some cracks are longer than Britain. Bright frost shines on the cracks. William Herschel found Titania long ago. It is named after a fairy queen. A robot called Voyager 2 flew past. It took the only close photos. Nobody has seen the other side yet.
As of August 2026, Uranus has 29 known moons. Titania is the largest of all of them. It is a sphere about 1,580 kilometres across. That is roughly half the width of our Moon.
It orbits Uranus at a distance of about 436,000 kilometres. One full orbit around Uranus takes just under 9 days. Like Uranus itself, Titania's orbit is tipped right over on its side. Titania is made of about equal parts ice and rock.
Its surface is grey and freezing cold, around minus 200 degrees Celsius. Long ago the inside froze and swelled, cracking the crust. This left enormous valleys on the surface, called chasmata. The longest, Messina Chasma, runs for about 1,500 kilometres.
Bright frost lines the walls of these deep valleys. Titania was discovered by William Herschel on 11 January 1787. It is named after the queen of the fairies in A Midsummer Night's Dream. Only one spacecraft has ever seen Titania up close.
Voyager 2 flew past in January 1986 and photographed one half of the moon. Scientists still wonder whether a hidden ocean lies beneath the ice.
Titania is the largest satellite of Uranus and, at about 1,578 km in diameter (JPL mean radius 788.9 km; NASA rounds to roughly 1,600 km), the eighth-largest moon in the solar system. It orbits at a semi-major axis of about 436,000 km with a period of 8.706 days, on a nearly circular path close to the planet's equatorial plane. Because Uranus's axis is tilted about 98 degrees, Titania's orbit is tilted with it, so each pole spends decades in continuous sunlight and then darkness. William Herschel discovered Titania and Oberon on 11 January 1787, six years after he found Uranus.
The moons were named by his son John Herschel in 1852, following the Uranian tradition of characters from Shakespeare and Alexander Pope; Titania is the fairy queen of A Midsummer Night's Dream. Note that the name is pronounced ti-TAH-nia, not like the Saturnian moon Titan. Its density of about 1.65 g/cm3 implies roughly equal proportions of water ice and rock, and models suggest a rocky core of about 520 km radius. Whether a thin liquid layer survives between core and ice shell remains an open question.
Voyager 2 is the only spacecraft to have visited the Uranian system. It passed about 365,000 km from Titania on 24 January 1986, imaging the sunlit southern hemisphere at modest resolution. Those images show a grey, moderately cratered surface cut by an extensive system of fault valleys, some nearly 1,600 km long, with bright deposits along their walls that may be frost. The largest, Messina Chasma, stretches about 1,500 km; the largest crater, Gertrude, is about 326 km across.
The chasmata are thought to record expansion of the crust as the interior froze early in Titania's history. Mean surface temperature is about 70 K, or roughly minus 200 degrees Celsius. Spectra show water ice and carbon dioxide ice, and there is a suggestion of an extremely tenuous CO2 exosphere. Uranus has 29 known moons as of August 2026.
No mission has returned since 1986, although a Uranus orbiter is a high priority in current planetary science planning.
Did you know?
- Titania's name is said ti-TAH-nia, not like Titan. Both come from old stories, but Titan is a moon of Saturn.
- Voyager 2 saw only Titania's southern half in 1986. Nobody has ever seen the other half up close.
- Titania's biggest canyon, Messina Chasma, is about 1,500 km long. That is longer than the whole of Great Britain.
Neighbours around Uranus
- Oberon
- Umbriel
- Ariel
- Miranda
- Puck
- Sycorax
- Portia
- Juliet
- Belinda
- Cressida
Questions children ask
Why does Titania have such big cracks?
Long ago Titania's inside was partly warm. As the water inside froze it took up more room, so the whole moon swelled a little. The icy crust could not stretch, so it split into long valleys called chasmata. Bright frost now lines their walls.
Is Titania bigger than our Moon?
No. Titania is about 1,580 km across, while our Moon is about 3,475 km across. So Titania is a little under half the width of the Moon. It is still the biggest moon Uranus has, and the eighth-biggest moon in the whole solar system.
Who found Titania and how?
William Herschel found Titania and Oberon on 11 January 1787 using a large telescope he built himself in Slough, England. He had discovered Uranus itself six years earlier. His son John Herschel chose the names from Shakespeare in 1852.
Could there be an ocean inside Titania?
Possibly. Titania is about half rock and half ice, and some models suggest a thin layer of salty liquid water could sit between the rocky core and the ice above. Nobody knows for sure. A future Uranus orbiter could measure this properly.
Quick quiz
Three questions for space cadets. Nothing is recorded.
- Which planet does Titania orbit?
- Which spacecraft is the only one to have visited Titania?
- Where does the name Titania come from?
Miranda
The Moon
Uranus