Miranda, also designated Uranus V, is the smallest and innermost of Uranus's five round satellites. It was discovered by Gerard Kuiper on 16 February 1948 at McDonald Observatory in Texas, and named after Miranda from William Shakespeare's play The Tempest. Like the other large moons of Uranus, Miranda orbits close to its planet's equatorial plane. Because Uranus orbits the Sun on its side, Miranda's orbit is perpendicular to the ecliptic and shares Uranus' extreme seasonal cycle.
At just 470 km in diameter, Miranda is one of the smallest closely observed objects in the Solar System that might be in hydrostatic equilibrium (spherical under its own gravity). The only close-up images of Miranda are from the Voyager 2 probe, which made observations of Miranda during its Uranus flyby in January 1986. During the flyby, Miranda's southern hemisphere pointed towards the Sun, so only that part was studied.
Miranda probably formed from an accretion disc that surrounded the planet shortly after its formation, and, like other large moons, it is likely differentiated, with an inner core of rock surrounded by a mantle of ice. Miranda has one of the most extreme and varied topographies of any object in the Solar System, including Verona Rupes, a 20-kilometer-high scarp that is the highest cliff in the Solar System, and chevron-shaped tectonic features called coronae. The origin and evolution of this varied geology, the most of any Uranian satellite, are still not fully understood, and multiple hypotheses exist regarding Miranda's evolution.
Discovery and name[]
Miranda was discovered on 16 February 1948 by planetary astronomer Gerard Kuiper using the McDonald Observatory's 82-inch (2,080 mm) Otto Struve Telescope. Its motion around Uranus was confirmed on 1 March 1948. It was the first satellite of Uranus discovered in nearly 100 years. Kuiper elected to name the object "Miranda" after the character in Shakespeare's The Tempest, because the four previously discovered moons of Uranus, Ariel, Umbriel, Titania and Oberon, had all been named after characters of Shakespeare or Alexander Pope. However, the previous moons had been named specifically after fairies, whereas Miranda was a human. Subsequently, discovered satellites of Uranus were named after characters from Shakespeare and Pope, whether fairies or not. The moon is also designated Uranus V.
Surface features[]
Due to Uranus's near-sideways orientation, only Miranda's southern hemisphere was visible to Voyager 2 when it arrived. The observed surface has patchwork regions of broken terrain, indicating intense geological activity in Miranda's past, and is criss-crossed by huge canyons, believed to be the result of extensional tectonics; as liquid water froze beneath the surface, it expanded, causing the surface ice to split, creating graben. The canyons are hundreds of kilometers long and tens of kilometers wide. Miranda also has the largest-known cliff in the Solar System, Verona Rupes, which has a height of 20 km (12 mi). Some of Miranda's terrain is possibly less than 100 million years old based on crater counts, while sizeable regions possess crater counts that indicate ancient terrain.
Close-up of the ring of concentric fault scarps around Elsinore Corona
While crater counts suggest that the majority of Miranda's surface is old, with a similar geological history to the other Uranian satellites, few of those craters are particularly large, indicating that most must have formed after a major resurfacing event in its distant past. Craters on Miranda also appear to possess softened edges, which could be the result either of ejecta or of cryovolcanism. The temperature at Miranda's south pole is roughly 85 K, a temperature at which pure water ice adopts the properties of rock. Also, the cryovolcanic material responsible for the surfacing is too viscous to have been pure liquid water, but too fluid to have been solid water. Rather, it is believed to have been a viscous, lava-like mixture of water and ammonia, which freezes at 176 K (−97 °C), or perhaps ethanol.
Miranda's observed hemisphere contains three giant 'racetrack'-like grooved structures called coronae, each at least 200 km (120 mi) wide and up to 20 km (12 mi) deep, named Arden, Elsinore and Inverness after locations in Shakespeare's plays. Inverness is lower in altitude than the surrounding terrain (though domes and ridges are of comparable elevation), while Elsinore is higher, The relative sparsity of craters on their surfaces means they overlay the earlier cratered terrain. The coronae, which are unique to Miranda, initially defied easy explanation; one early hypothesis was that Miranda, at some time in its distant past, (prior to any of the current cratering) had been completely torn to pieces, perhaps by a massive impact, and then reassembled in a random jumble. The heavier core material fell through the crust, and the coronae formed as the water re-froze.
Gallery[]
Refrences[]
https://en.wikipedia.org/wiki/Miranda_(moon)
https://solarsystem.nasa.gov/moons/uranus-moons/miranda/in-depth/