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• THE LUNAR EXPLORER ARCHIVES
• MOON
• MARS
• SOLAR SYSTEM
• DEEP SKY

A R C H I V E S

According to our present Knowledge, the Surface of the Uranian moon Miranda should mostly be made of Water Ice; however, this low-density Celestial Body may also contain, in its interior, Silicate Rock and, maybe, some Organic Compounds. Miranda's Surface has some really bizarre-looking "Patchwork Regions" of Broken (meaning, in this case, deeply and massively fractured) Terrain, which likely indicates the occurrence of some extremely intense Geological Activity in the moon's past; to complete this unusual scenario, we underline that Miranda is also criss-crossed by huge Canyons. Large "Racetrack-like Grooved Structures" (known as Coronae and well visible all over Miranda), may have formed by way of Extensional Processes which occurred at the tops of the Diapirs (---> upwellings of warm ice). On the other hand, the Ridges visible on Miranda probably represent the consequence of "Extensional Tilt Blocks", while the Canyons characterizing most of the Surface of this moon, could just be Grabens that formed by way of Extensional Faulting. Other Surface Features present on Miranda may be due to Cryovolcanic Eruptions of Icy Magma. The Diapirs that we have already mentioned herebefore, might also have changed the Density Distribution of the heavy Materials existing within the moon: a fact, this one, which could have easily caused Miranda, in time, to reorient itself (this process, if it actually happened, is substantially similar to the one that is believed to have occurred at the Saturnian - as you know still geologically active moon - Enceladus).

Furthermore, Miranda's past Geological Activity is believed to have been substantially (if not exclusively) driven by Tidal Heating at a time when its orbit was more eccentric than it is now. In fact, early in its history, Miranda could have been captured into a 3:1 Orbital Resonance with another Uranian moon (Umbriel), from which it subsequently (and for reasons that shall likely remain unknown to us) escaped. The Resonance, however, would have increased the Orbital Eccentricity of Miranda, thus causing the occurrence of a relatively common phenomenon known as "Tidal Friction" (in other words: the occurrence of very frequent - even though, perhaps, time-varying - Tidal (---> Gravitational) Influences from Uranus onto Miranda, have caused, in specific moments during the orbit of the Minor Celestial Body (Miranda) around the Parent Planet (Uranus), some recurrent, rapid and elevated (likely VERY elevated) warming up of the Minor Body's interior). In the Uranian System, due to both the Gas-Giant Planet's lesser degree of oblateness, as well as the larger - relative - size of its Major Moons, it is also believed that the escape from a Mean Motion Resonance is theoretically much easier than it could be for other Natural Satellites orbiting around, for instance, the Gas-Giant Planets Jupiter and Saturn.

Miranda's Orbital Inclination (4,34°) is also unusually high for a Celestial Body whose orbit pattern makes it go so close to its Parent Planet. It has been speculated that Miranda probably escaped from its Resonance with Umbriel through a so-called Secondary Resonance, and the mechanism of this escape is believed to explain why its Orbital Inclination is more than 10 times the one of the other large Uranian moons. Last, but not least, Miranda may have also, once, have been in a 5:3 Resonance with Ariel: another event which, if true, could have also contributed to its internal heating. However, the maximum heating attributable to the Resonance with Umbriel was likely about three times greater. An earlier theory, proposed shortly after the NASA - Voyager 2 Spacecraft Fly-By, speculated that a previous and defined spatial location (---> orbit) of Miranda was shattered (---> disrupted) by a Massive Impact, with most of the fragments resulting from this alleged Cosmic Catastrophe slowly getting back together, with the denser (and therefore heavier) ones sinking down, so to produce, after some time (likely a VERY long time), the current - and extremely strange - orbital pattern of this bizarre-looking (the shape of Miranda is, actually, "Ovoidal"...) and fascinating Uranian moon.

The frame has been colorized in Absolute Natural Colors (such as the colors that a normal - meaning "in average" - human eye would actually perceive if someone were onboard the NASA - Voyager 2 Spacecraft and then looked outside, towards the Uranian moon Miranda), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team.