What is Miranda?

Michael Anissimov

Miranda is a moon of Uranus, its smallest and innermost. Miranda is about 1/8th the size of our moon, 290 miles in diameter (235.8 km), but still spherical. Miranda is unusual among the moons of the solar system in that it's most immediately apparent features are not craters, but its jagged and craggy terrain, including a cliff over three miles high. Miranda looks similar to how a golf ball might look if put in a blender. This moon was first discovered by Gerard Kuiper in 1948.

In January 1986, NASA's Voyager 2 probe did a close fly-by of Miranda.
In January 1986, NASA's Voyager 2 probe did a close fly-by of Miranda.

From Earth and space-based telescopes, Miranda looks just like a blurry dot, but in January 1986 the Voyager 2 probe did a close fly-by, giving us detailed pictures which are now standard for sections on Miranda in astronomy books.

Miranda is the most geologically active moon in the Uranian system, and was much more active in the past. Besides huge cliffs, it is criss-crossed by numerous canyons and upwellings called coronae. The likely source of Miranda's geological activity is tidal warming, caused by its eccentric orbit.

Miranda is unusual for being one of the only bodies in the solar system to have a longer pole-to-pole diameter than equatorial diameter. This is likely caused by its intense geological activity and internal reshuffling in the past. Another theory is that Miranda suffered a gigantic impact in the past, which caused it to be blown to pieces, which then reformed from mutual gravitational attraction. Its ridges are said to have a "sawtooth" pattern.

At four degrees, Miranda's orbital inclination is about 10 times greater than other Uranian satellites, and is quite out of the ordinary for a body that orbits so close to its parent planet.

Miranda has an escape velocity of 0.19 km/s, or 425 mph. A fast jet or passenger plane would be able to launch off into outer space, if it had an atmosphere.

Some planetary scientists have called Miranda "the solar system's strangest moon."

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