The Solar System


What are some of the characteristics of Uranus’s moons?

The moons of Uranus are smallish structures made of ice and rock, ranging in size from about 15 miles (25 kilometers) to 1,000 miles (1,600 kilometers) across. The two largest, Oberon and Titania, were discovered by William Herschel (1738–1822); the next largest two moons, Umbriel and Ariel, were discovered in 1851 by William Lassel (1799–1880). It was not until 1948 that Gerard Kuiper (1905–1973) detected Miranda, the fifth Uranian moon. The Voyager 2 flew by Uranus in January and February 1986, and discovered at least ten new moons—all smaller than about 90 miles (145 kilometers) across. A dozen more small moons have been confirmed since then; many of them have retrograde orbits, suggesting that they were small solar system objects captured by the gravity of Uranus.

Like the larger moons of Saturn and Jupiter, the five larger moons of Uranus have varying amounts of geologic features, including craters, cliffs, and canyons. Oberon, for instance, shows an ancient, heavily cratered surface, which indicates there has been little geologic activity there; the craters remain as they were originally formed, and no lava has filled them in. In contrast, Titania is punctuated by huge canyons and fault lines, indicating that its crust has shifted significantly over time.


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