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Miranda

Miranda[1]

 

Miranda

 

Orbit: 129,850 km from Uranus
Gravity: 0.079 m/s²
Orbital period: 34 hours
Circumference: 1,482 km
Diameter: 472 km
Mass: 6.3e19 kg
Miranda is the smallest and innermost of Uranus’s five major moons. It was discovered by Gerard Kuiper on February 16, 1948 at McDonald Observatory. Voyager 2 was forced to fly close to  Uranus in order to get the boost it needed to go  on to  Neptune and due to the orientation of  the whole system at almost right angles to the ecliptic only Miranda was approached closely.  Before Voyager, of course, little  was known about Miranda and as it  is not the largest or in any other way  remarkable, it probably would not have been chosen as the prime target at  Uranus. Voyager’s good luck held up,       however, as Miranda turned out to be  by far the most interesting.
Miranda is the smallest and innermost of Uranus’s five major moons
Miranda is about half water ice and half rocky material. Miranda’s surface is all mixed up with heavily cratered terrain  intermixed with weird grooves, valleys and cliffs (one over 5 kilometers  high; left).At first, Voyager 2’s images of Miranda were a mystery.  Everyone had  expected that Uranus’ moons would show very little history of  internal activity (like Callisto). Explaining  the bizarre hitherto unknown  terrain proved quite an embarrassment to  those who had to do it on live TV.  Their usual impressive and esoteric  technical jargon gave out and they had to resort to using such terms as  “chevron” (right),  “race track”, and “layer cake” to describe  Miranda’s unique features.
Miranda is the smallest and innermost of Uranus’s five major moons

It was initially thought that Miranda had been completely shattered and  reassembled       several times in its history, each time burying some parts of  the original  surface  and exposing some of the interior. Now,  however, a more mundane explanation involving the upwelling      of partially  melted ices seems to be in favor.

Voyager 2 passed so close to Miranda and the light levels are so low there (almost 3 billion km from the Sun) that special measures had to be employed to avoid smearing the images. This was accomplished by rotating the entire  spacecraft while the camera’s shutter was open to compensate for its motion.  The resulting images have the best resolution  of the entire mission.

It is actually possible to see Uranus’s 4 largest moons with an amateur  telescope, but Miranda is a real challenge. Perhaps with a very dark sky and a  telescope with  an 18 inch (50 cm) aperture or more it might be possible.

 

 

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