Miranda

What is Miranda?

Moons· Diameter 472 km. The smallest major moon of Uranus and one of the strangest landscapes in the solar system — a patchwork of mismatched terrains and Verona Rupes, a 20-km cliff, the tallest known. See its quick inner orbit in the orbit view.

The orbit of Miranda at this moment: https://nowsky.org/solar/orbit?fw=moon:uranus:miranda&sp=0.003 — replayed live, no login.

Orbit and size

Figures are representative approximations. Source: compiled from NASA and IAU public data.

Parent planet and sibling moons

Frequently asked

How big is Miranda?

472 km.

How far is Miranda from Earth?

129,900 km.

What is notable about Miranda?

20-km cliff Verona Rupes.

Which planet does Miranda orbit?

Uranus.

Twelve minutes of falling from Verona Rupes

Verona Rupes on Miranda is, at 20 km, the highest known cliff in the solar system. Miranda's surface gravity is 0.8 percent of Earth's, so stepping off the top means about twelve minutes of falling and a landing at roughly 200 km/h. On Earth a 20 km drop passes the speed of sound within a minute. The arithmetic says one airbag, not a parachute, would be enough to survive.

How the cliff formed is the same puzzle as Miranda's patchwork terrain. One account has the moon shattered and reassembled, the crust tearing as large fragments sank; another has ice from the interior rising and pulling the surface apart. Voyager 2 in 1986 photographed only the southern hemisphere, and nobody has yet seen the north.

The moon in depth

Miranda was discovered by Gerard Kuiper in 1948 and named for the heroine of Shakespeare's The Tempest. At 472 km across it is the smallest of the five major moons, orbiting 130,000 km from Uranus every 1.41 days. Voyager 2 passed closer to Miranda than to any other Uranian moon, so it holds the sharpest images in the system.

Those images were a shock. Ancient cratered plains sit beside racetrack-like ovals of concentric grooves called coronae, all tangled with giant faults and cliffs, as if pieces of different worlds had been stitched together. Early theories held that the moon had been smashed apart and reassembled; today the favored view is that tidal heating drove warm ice upward and overturned the crust. Verona Rupes, about 20 km tall, is the highest known cliff — in Miranda's feeble gravity a jump from the top would take 12 minutes to land.

Track Uranus in the orbit view and zoom in to see Miranda whipping around on the innermost orbit. Its path is inclined 4.3 degrees to the planet's equator, the most of any large moon, and a past orbital resonance that stirred and heated its interior is the leading explanation for its bizarre face.

Related

Figures are representative approximations. Simulated positions use J2000 mean elements.