Titania (moon)

Titania is the largest moon of Uranus and the eighth-largest moon in the entire Solar System. It has a diameter of 1,578 kilometers, which is about 981 miles. Titania was discovered by the astronomer William Herschel in 1787. It is named after the queen of the fairies in Shakespeare's play A Midsummer Night's Dream.

This moon is made up of about equal parts ice and rock. Scientists think Titania has a rocky core surrounded by a layer of ice, and there might be liquid water deep inside it. Its surface is dark and a little red, and it has many large craters from collisions with space rocks. However, it has fewer craters than Oberon, another moon of Uranus.

Titania also has huge valleys and cliffs that formed when its interior expanded long ago. Like the other big moons of Uranus, Titania probably formed from a ring of material that surrounded Uranus when the planet was young. In the early 2000s, scientists used special instruments to study Titania and found evidence of water ice and frozen carbon dioxide on its surface. This suggests Titania might have a very thin layer of air made of carbon dioxide. The only spacecraft to visit the Uranian system was Voyager 2 in 1986, and it sent back pictures that helped scientists map about 40% of Titania's surface.

Discovery and naming

Titania was discovered by William Herschel on January 11, 1787, the same day he found another moon of Uranus named Oberon. For almost 50 years, no one else could see these moons except with Herschel's telescope, though today they can be spotted with a good amateur telescope from Earth.

All of Uranus's moons are named after characters from stories by William Shakespeare or Alexander Pope. Titania’s name comes from the Queen of the Fairies in the play A Midsummer Night's Dream. The names were suggested in 1852 by Herschel’s son John at the request of William Lassell, who had found two other moons, Ariel and Umbriel, the year before. We’re not sure if John Herschel or Lassell came up with the names first.

Orbit

Titania orbits Uranus at a distance of about 436,000 kilometres. It is the second farthest of Uranus's five major moons after Oberon. Its path around Uranus is almost circular and tilts only slightly compared to Uranus's equator.

Titania takes around 8.7 days to complete one orbit, which is the same time it takes to spin once. This means one side of Titania always faces Uranus.

Titania's orbit is inside Uranus's magnetosphere. This area of charged particles can hit the moons. Because Uranus spins on its side, its moons, including Titania, go through big changes in seasons. Each pole can be in total darkness for 42 years, then in continuous sunlight for another 42 years. The Voyager 2 spacecraft flew by during a time when the southern half of Titania was well-lit.

Every 42 years, when Uranus reaches a certain point in its orbit, its moons can pass in front of or behind each other as seen from Earth. Some of these events were watched in 2007–2008, including times when Titania passed behind another moon named Umbriel.

Composition and internal structure

Titania is the biggest moon of Uranus and the eighth biggest in the whole Solar System. It is made of about half water ice and half denser materials, such as rock and other heavy substances. Scientists have found signs of water ice on its surface using special telescopes.

Besides water, a small amount of carbon dioxide has also been found on Titania, mostly on one side of the moon. We are not sure yet how it got there, but it might have come from the moon’s own materials or from particles around Uranus. Titania might also have a rocky center surrounded by a layer of ice, and there is a chance it could have a warm ocean deep inside.

Surface features

Titania is one of Uranus's moons. Its surface looks different in different places. It is not as dark as some moons but brighter than others. Scientists have found three main types of features on its surface: craters, deep valleys called chasmata (or canyons), and steep cliffs called rupes (or scarps).

Titania's surface has fewer craters than some other moons, which suggests it is younger. The largest crater, called Gertrude, is about 326 kilometers wide. Some craters have bright icy material around them. The moon also has huge cracks and valleys, with the biggest one, Messina Chasma, stretching almost 1,500 kilometers. These valleys and cliffs were formed by the moon stretching and cracking over time.

Atmosphere

Titania shows signs of carbon dioxide on its surface. This suggests it might have a very thin, seasonal atmosphere made of this gas, similar to another moon called Callisto.

Other gases like nitrogen or methane are unlikely because Titania’s gravity is too weak to hold onto them.

In 2001, scientists watched Titania pass in front of a bright star. This helped them learn more about the moon’s size and whether it has an atmosphere. They found that if Titania does have an atmosphere, it is much thinner than those of Triton or Pluto. The way Uranus spins affects how much sunlight its moons receive, which might cause carbon dioxide to move between different parts of Titania’s surface. Over billions of years, Titania may have lost a lot of its carbon dioxide.

Origin and evolution

Titania likely formed from a disc of gas and dust around Uranus after the planet was created. This disc may have had less water than the moons of Saturn and more nitrogen and carbon. As Titania formed over thousands of years, impacts heated its outer layer. Later, cooling and heating from radioactive elements inside caused its surface to crack, possibly forming canyons we see today.

Scientists think that if certain substances were present, parts of Titania might have melted, creating a layer of liquid water rich in ammonia near its center. If the temperature dropped too low, this ocean might have frozen, which could have helped form more cracks on the surface. We still have much to learn about Titania’s history and whether it might still have hidden oceans beneath its surface.

Exploration

Main article: Exploration of Uranus

The only close-up pictures of Titania come from the Voyager 2 probe. It took photos when it flew by Uranus in January 1986. Because Voyager 2 was far from Titania, the pictures show details on the surface. These images cover part of Titania but only a small part is clear enough to study.

No other spacecraft has visited Uranus or Titania. There were ideas to send the Cassini probe to Uranus, but these plans were dropped. Another idea was a mission called the Uranus orbiter and probe, which scientists looked at around 2010. Uranus was also considered for a path for a spacecraft heading toward interstellar space called the Innovative Interstellar Explorer.

In 2023, scientists said a mission to orbit Uranus and drop a probe was very important for future space exploration. This mission could help us learn more about Titania and the other moons of Uranus.