Miranda is the smallest and innermost of Uranus’ five major moons, and its surface looks stitched together from spare parts - ancient cratered plains butt directly against huge chevron-shaped grooved regions called coronae. When Voyager 2 flew past in 1986, this little moon turned out to be the strangest sight in the whole Uranus system.
Verona Rupes, a cliff roughly 20 km high, is the tallest known cliff in the Solar System.
Gravity is so weak that a fall from the top of Verona Rupes would last around 12 minutes.
It was discovered in 1948 - nearly a century after the next of Uranus’ major moons.
The Frankenstein moon
A moon just 472 km across should have frozen solid long ago and stayed geologically dead. Yet Miranda’s jumbled patchwork says otherwise: it was probably caught for a time in an orbital resonance with Umbriel, and the resulting tidal heating sent warm ice welling up from inside, breaking and remaking parts of the crust. Even tiny worlds can be reworked - given the right gravitational choreography.
Physical characteristics
Diameter
472 km
Mass
6.600e+19 kg
Surface gravity
0.08 m/s²
Density
1.2 g/cm³
Tidally locked
Yes
Mean temperature
-200 °C
Geometric albedo
0.32
Atmosphere and composition
Atmosphere
None detected.
Composition
Water ice mixed with silicate rock; the least dense of the five major Uranian moons.
Discovery
Discovered by
Gerard Kuiper
Year
1948
How
82-inch telescope at McDonald Observatory
Missions
Voyager 2NASA · Flyby probe · 1977 · active
Launched 16 days before its twin, Voyager 2 is the only spacecraft ever to visit all four giant planets - Jupiter, Saturn, Uranus and Neptune. It entered interstellar space in 2018 and is still returning data.