Uranus' Moon Miranda
Miranda (Uranus V)

Voyager 2 - 1986.1.24

Discovered by: Gerard Kuiper
Date of discovery: 1948
Mass (kg): 6.33e+19
Mass (Earth = 1): 1.0592e-05
Equatorial radius (km): 235.8
Equatorial radius (Earth = 1): 3.6971e-02
Mean density (gm/cm³): 1.15
Mean distance from Uranus (km): 129,780
Rotational period (days): 1.413479
Orbital period (days): 1.413479
Mean orbital velocity (km/sec): 6.68
Orbital eccentricity: 0.0027
Orbital inclination (degrees): 4.22
Escape velocity (km/sec): 0.189
Visual geometric albedo: 0.27
Magnitude (Vo): 16.3
Mean surface temperature: -187°C

Miranda [mih-RAN-dah] is not one of the larger satellites of Uranus; however, it was the one that was approached the closest by Voyager 2. This was not the satellite scientists would have chosen to get close to if they had a choice, but they had no choice. Voyager 2 had to fly close to the planet in order to get the boost it needed to go to Neptune. The resolution at which the larger satellites were photographed was around 2 to 3 kilometers (1.2 to 1.9 miles). On the other hand, details on the order of a few hundred meters can be seen on Miranda. Fortunately, Miranda turned out to be the most remarkable of all the satellites.

Miranda is a small satellite with a diameter of 470 kilometers (290 miles).

Its surface is unlike anything in the solar system with features that are jumbled together in a haphazard fashion. Miranda consists of huge fault canyons as deep as 20 kilometers (12 miles), terraced layers and a mixture of old and young surfaces. The younger regions might have been produced by incomplete differentiation of the moon, a process in which upwelling of lighter material surfaced in limited areas. Alternatively, scientists believe that Miranda may have been shattered as many as five times during its evolution. After each shattering the moon would have reassembled from the remains of its former self with portions of the core exposed and portions of the surface buried. Miranda's appearence can be explained by theories, but the real reason is still unknown.

Given Miranda's small size and low temperature (-187° C or -335° F), the degree and diversity of the tectonic activity on this moon has surprised scientists. It is believed that an additional heat source such as tidal heating caused by the gravitational tug of Uranus must have been involved. In addition, some means must have mobilized the flow of icy material at low temperatures.

Miranda was named after the daughter of the magician Prospero in Shakespeare's play The Tempest.

Uranus' moon Miranda is shown in a computer-assembled mosaic of images obtained January 24, 1986, by the Voyager 2 spacecraft. Miranda is the innermost and smallest of the five major Uranian satellites, just 480 kilometers (about 300 miles) in diameter. This image is a full-disc, south-polar view of the moon showing the varying geologic provinces of Miranda. The moon's surface consists of two major strikingly different types of terrain. One is an old, heavily cratered, rolling terrain with relatively uniform albedo, or reflectivity. The other is a young, complex terrain characterized by sets of bright and dark bands, scarps and ridges. These are features found in the ovoid regions at right and left and in the distinctive chevron feature below and right of center.

(Courtesy NASA/JPL)