Editing Miranda (moon) (section)

=== Impact craters ===
During the close flyby of ''Voyager 2'' in January 1986, only the craters on the southern hemisphere of Miranda could be observed. They generally had diameters of over {{cvt|500|m}}, representing the limit of resolution of the digital images transmitted by the probe during its flight.<ref name=Plescia1987_442 /> These craters have very varied morphologies. Some have well-defined borders and are sometimes surrounded by ejecta deposits characteristic of [[impact crater|impact craters]]. Others are very degraded and sometimes barely recognizable, as their topography has been altered.<ref name=Plescia1987_443>{{harvsp|J. B. Plescia|1987|p=443|id=Plescia1987}}</ref> The age of a crater does not give an indication of the date of formation of the terrain it marked. On the other hand, this date depends on the number of craters present on a site, regardless of their age.<ref name=Plescia1987_448>{{harvsp|J. B. Plescia|1987|p=448|id=Plescia1987}}</ref> The more impact craters a terrain has, the older it is. Scientists use these as "planetary chronometers"; they count observed craters to date the formation of the terrain of inert natural satellites devoid of atmospheres, such as [[Callisto (moon)|Callisto]].<ref name=Brahic2010_185-186>{{harvsp|A. Brahic|2010|p=185–186|id=Brahic2010}}</ref>

No multiple ring crater, nor any complex crater with a central peak, has been observed on Miranda.<ref name=Plescia1987_443/> Simple craters, that is to say whose cavity is bowl-shaped, and transitional craters (with a flat bottom) are the norm, with their diameter not correlated to their shape.<ref name=Plescia1987_443/> Thus simple craters of more than {{cvt|15|km}} are observed while elsewhere transitional craters of {{cvt|2.5|km}} have been identified.<ref name=Plescia1987_443/> Ejecta deposits are rare, and are never associated with craters larger than {{cvt|15|km}} in diameter.<ref name=Plescia1987_443/> The ejecta that sometimes surround craters with a diameter less than {{cvt|3|km}} appear systematically brighter than the material surrounding them. On the other hand, ejecta associated with craters of size between {{cvt|3|km}} and {{cvt|15|km}} are generally darker than what surrounds them (the albedo of the ejecta is lower than that of the matter surrounding them).<ref name=Plescia1987_443/> Finally, some ejecta deposits, associated with diameters of all sizes, have an albedo comparable to that of the material on which they rest.<ref name=Plescia1987_443/>

==== In regiones ====
In some regiones, and particularly in those of the visible part of the anti-Uranian hemisphere (which continually turns its back on the planet), craters are very frequent. They are sometimes stuck to each other with very little space between each one.<ref name=Plescia1987_443/> Elsewhere, craters are less frequent and are separated by large, weakly undulated surfaces.<ref name=Plescia1987_443/> The rim of many craters is surrounded by luminous material while streaks of dark material are observed on the walls which surround the bottom of the craters.<ref name=Plescia1987_443/> In Matuna Regio, between the craters Truncilo and Fransesco, there is a gigantic circular geological structure of {{cvt|170|km}} in diameter which could be a [[Impact crater|basin impact]] very significantly degraded.<ref name=Plescia1987_443/> These findings suggest that these regions contain a shiny material at shallow depth, while a layer of dark material (or a material which darkens upon contact with the external environment) is present, at greater depth.<ref name=Plescia1987_444/>

==== In coronae ====
Craters are statistically up to ten times less numerous in the coronae than in the anti-Uranian regions, which indicates that these formations are younger.<ref name=Plescia1987_449>{{harvsp|J. B. Plescia|1987|p=449|id=Plescia1987}}</ref>

The density of impact craters could be established for different areas of Inverness, and made it possible to establish the age of each.<ref name=Plescia1987_450>{{harvsp|J. B. Plescia|1987|p=450|id=Plescia1987}}</ref> Considering these measurements, the entire geological formation was formed in a relative unit of time.<ref name=Plescia1987_451>{{harvsp|J. B. Plescia|1987|p=451|id=Plescia1987}}</ref> However, other observations make it possible to establish that the youngest zone, within this crown, is the one which separates the "chevron", from Argier Rupes.<ref name=Plescia1987_451/>

The density of impact craters in the core and in the Arden belt is statistically similar.<ref name=Plescia1987_450/> The two distinct parts of this formation must therefore have been part of a common geological episode.<ref name=Plescia1987_450/> Nevertheless, the superposition of craters on bands of the central core of Arden indicates that its formation preceded that of the scarps which surround it.<ref name=Plescia1987_450/> The data from the impact craters can be interpreted as follows: the interior and marginal zones of the corona, including most of the albedo bands, were formed during the same period of time.<ref name=Plescia1987_450/> Their formation was followed by later tectonic developments which produced the high-relief fault scarps observed along the edge of the crown near longitude 110°.<ref name=Plescia1987_450/>

The density of impact craters seems the same in the structure surrounding Elsinore as in its central core.<ref name=Plescia1987_452>{{harvsp|J. B. Plescia|1987|p=452|id=Plescia1987}}</ref> The two zones of the crown seem to have formed during the same geological period, but other geological elements suggest that the perimeter of Elsinore is younger than its core.<ref name=Plescia1987_452/>

==== Other observations ====
The number of craters should be higher in the hemisphere at the apex of the orbital movement than at the antapex.<ref name=Plescia1987_454>{{harvsp|J. B. Plescia|1987|p=454|id=Plescia1987}}</ref> However, it is the anti-Uranian hemisphere which is densest in craters.<ref name=Plescia1987_455>{{harvsp|J. B. Plescia|1987|p=455|id=Plescia1987}}</ref> This situation could be explained by a past event having caused a reorientation of Miranda's axis of rotation by 90° compared to that which is currently known.<ref name=Plescia1987_455/> In this case, the paleoapex hemisphere of the moon would have become the current anti-Uranian hemisphere.<ref name=Plescia1987_455/> However, the count of impact craters being limited to the southern hemisphere only, illuminated during the passage of the Voyager 2 probe, it is possible that Miranda has experienced a more complex reorientation and that its paleoapex is located somewhere in the northern hemisphere, which has not yet been photographed.<ref name=Plescia1987_455/>