Space Topics: Uranus
Uranus' Moon Miranda
Diameter: 480 x 468.4 x 465.8 kilometers
Orbital distance: 129,900 kilometers from Uranus
Orbital period: 1.41 days
Orbital inclination: 4.3 degrees
Discovery: 1948 by Gerald Kuiper
Miranda, the smallest and innermost of Uranus’ five major moons, at
first looks like something squashed together using pieces scavenged from the
scrap heap of planetary formation. Its rolling, cratered terrains resemble
the ancient highlands of our Moon. Its coronae are namesakes to round
fractured zones on Venus. Ridges and grooves within the coronae resemble
striated lanes on Jupiter’s moon Ganymede and Saturn’s moon Enceladus. The
Miranda we see today may be the latest incarnation of the moon; previous versions
could have been smashed to bits by large debris that crossed its orbital path
and then was reassembled by gravity.
The three coronae of Miranda -- Arden, Inverness, and Elsinore -- are flat-sided
with rounded corners, each resembling an oval racetrack. They likely represent
the locations of upwelling in Miranda’s interior. The smashing
and reassembly of Miranda would have left it a thorough mixture of rockier
and icier materials. But with a little bit of heat, perhaps from the
tidal effects of a temporary orbital resonance with Umbriel, the denser rock
will sink inward while the lighter ice moves outward, a process called “differentiation.” Yet,
for some reason, the process didn’t finish, and Miranda was caught in
the act of differentiating.
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Miranda at close range
Voyager 2 approached closer to Miranda than to any other of Uranus'
satellites. In this view the striped terrain of Inverness Corona juts
into lumpy, more cratered terrain. Jagged mountains march off to Miranda's
limb. Credit: NASA/JPL |
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