Home      Discussion      Topics      Dictionary      Almanac
Signup       Login
Miranda (moon)

Miranda (moon)

Overview
Miranda is the smallest and innermost of Uranus
Uranus
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...

' five major moon
Natural satellite
A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called its primary. The two terms are used synonymously for non-artificial satellites of planets, of dwarf planets, and of minor planets....

s.

It was discovered by Gerard Kuiper
Gerard Kuiper
Gerard Peter Kuiper , Netherlands – December 24, 1973, Mexico City) was a Dutch-American astronomer after whom the Kuiper belt was named.-Early life:...

 on February 16, 1948 at McDonald Observatory
McDonald Observatory
The McDonald Observatory is an astronomical observatory located near the unincorporated community of Fort Davis in Jeff Davis County, Texas, United States. The facility is located on Mount Fowlkes and Mount Locke in the Davis Mountains of West Texas...

. It was named after Miranda
Miranda (Shakespeare)
In Shakespeare's play The Tempest, Miranda is the beautiful daughter of the old Duke Prospero.Cast away with her father since she was three years old, she has lived an extremely sheltered existence. Though she has received a well-rounded education from her father, she is desperately lacking in real...

 from William Shakespeare
William Shakespeare
William Shakespeare was an English poet and playwright, widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's national poet and the "Bard of Avon"...

's play The Tempest by Kuiper in his report of the discovery. The adjectival form of the name is Mirandan. It is also designated Uranus V.

So far the only close-up images of Miranda are from the Voyager 2
Voyager 2
The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space...

probe, which made observations of the moon during its Uranus flyby in January, 1986.
Discussion
Ask a question about 'Miranda (moon)'
Start a new discussion about 'Miranda (moon)'
Answer questions from other users
Full Discussion Forum
 
Unanswered Questions
Encyclopedia
Miranda is the smallest and innermost of Uranus
Uranus
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...

' five major moon
Natural satellite
A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called its primary. The two terms are used synonymously for non-artificial satellites of planets, of dwarf planets, and of minor planets....

s.

It was discovered by Gerard Kuiper
Gerard Kuiper
Gerard Peter Kuiper , Netherlands – December 24, 1973, Mexico City) was a Dutch-American astronomer after whom the Kuiper belt was named.-Early life:...

 on February 16, 1948 at McDonald Observatory
McDonald Observatory
The McDonald Observatory is an astronomical observatory located near the unincorporated community of Fort Davis in Jeff Davis County, Texas, United States. The facility is located on Mount Fowlkes and Mount Locke in the Davis Mountains of West Texas...

. It was named after Miranda
Miranda (Shakespeare)
In Shakespeare's play The Tempest, Miranda is the beautiful daughter of the old Duke Prospero.Cast away with her father since she was three years old, she has lived an extremely sheltered existence. Though she has received a well-rounded education from her father, she is desperately lacking in real...

 from William Shakespeare
William Shakespeare
William Shakespeare was an English poet and playwright, widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's national poet and the "Bard of Avon"...

's play The Tempest by Kuiper in his report of the discovery. The adjectival form of the name is Mirandan. It is also designated Uranus V.

So far the only close-up images of Miranda are from the Voyager 2
Voyager 2
The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space...

probe, which made observations of the moon during its Uranus flyby in January, 1986. During the flyby the southern hemisphere of the moon was pointed towards the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

 so only that part was studied. Miranda shows more evidence of past geologic activity than any of the other Uranian satellites.

Physical characteristics



Miranda's surface may be mostly water ice, with the low-density body also probably containing silicate
Silicate
A silicate is a compound containing a silicon bearing anion. The great majority of silicates are oxides, but hexafluorosilicate and other anions are also included. This article focuses mainly on the Si-O anions. Silicates comprise the majority of the earth's crust, as well as the other...

 rock and organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

s in its interior.

Miranda's surface has patchwork regions of broken terrain indicating intense geological activity in the moon's past, and is criss-crossed by huge canyons. Large 'racetrack'-like grooved structures, called coronae
Corona (planetary geology)
In planetary geology, a corona is an oval-shaped feature. Coronae appear on both the planet Venus and Uranus's moon Miranda and may be formed by upwellings of warm material below the surface.-Coronae on Venus:...

, may have formed via extensional
Rift
In geology, a rift or chasm is a place where the Earth's crust and lithosphere are being pulled apart and is an example of extensional tectonics....

 processes at the tops of diapir
Diapir
A diapir is a type of intrusion in which a more mobile and ductily-deformable material is forced into brittle overlying rocks. Depending on the tectonic environment, diapirs can range from idealized mushroom-shaped Rayleigh-Taylor instability-type structures in regions with low tectonic stress...

s, or upwellings of warm ice. The ridges probably represent extensional tilt blocks. The canyons probably represent graben
Graben
In geology, a graben is a depressed block of land bordered by parallel faults. Graben is German for ditch. Graben is used for both the singular and plural....

 formed by extensional fault
Extensional tectonics
Extensional tectonics is concerned with the structures formed, and the tectonic processes associated with, the stretching of the crust or lithosphere.-Deformation styles:...

ing. Other features may be due to cryovolcanic
Cryovolcano
A cryovolcano is a volcano that erupts volatiles such as water, ammonia or methane, instead of molten rock. Collectively referred to as cryomagma or ice-volcanic melt, these substances are usually liquids and form plumes, but can also be in vapour form...

 eruptions of icy magma. The diapirs may have changed the density distribution within the moon, which could have caused Miranda to reorient itself, similar to a process believed to have occurred at Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...

's geologically active moon Enceladus
Enceladus (moon)
Enceladus is the sixth-largest of the moons of Saturn. It was discovered in 1789 by William Herschel. Until the two Voyager spacecraft passed near it in the early 1980s very little was known about this small moon besides the identification of water ice on its surface...

. Miranda is one of the few bodies in the solar system in which the equatorial circumference is shorter than the pole-to-pole circumference, probably a consequence of the diapir activity.

Miranda's past geological activity is believed to have been driven by tidal heating
Tidal heating
Tidal heating occurs through the tidal friction processes: orbital and rotational energy are dissipated as heat in the crust of the moons and planets involved. Io, a moon of Jupiter, is the most volcanically active body in the solar system, with no impact craters surviving on its surface...

 at a time when its orbit was more eccentric than currently. Early in its history, Miranda was apparently captured into a 3:1 orbital resonance
Orbital resonance
In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other, usually due to their orbital periods being related by a ratio of two small integers. Orbital resonances greatly enhance the mutual gravitational influence of...

 with Umbriel
Umbriel (moon)
Umbriel is a moon of Uranus discovered on October 24, 1851, by William Lassell. It was discovered at the same time as Ariel and named after a character in Alexander Pope's poem The Rape of the Lock. Umbriel consists mainly of ice with a substantial fraction of rock, and may be differentiated into a...

, from which it subsequently escaped. The resonance would have increased orbital eccentricity
Orbital eccentricity
The orbital eccentricity of an astronomical body is the amount by which its orbit deviates from a perfect circle, where 0 is perfectly circular, and 1.0 is a parabola, and no longer a closed orbit...

; resulting tidal friction due to time-varying tidal force
Tidal force
The tidal force is a secondary effect of the force of gravity and is responsible for the tides. It arises because the gravitational force per unit mass exerted on one body by a second body is not constant across its diameter, the side nearest to the second being more attracted by it than the side...

s from Uranus would have caused warming of the moon's interior. In the Uranus system, due to the planet's lesser degree of oblateness, and the larger relative size of its satellites, escape from a mean motion resonance is much easier than for satellites of Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

 or Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...

. Miranda's orbital inclination
Inclination
Inclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit...

 (4.34°) is unusually high for a body so close to the planet. Miranda probably escaped from its resonance with Umbriel via a secondary resonance, and the mechanism of this escape is believed to explain why its orbital inclination is more than 10 times those of the other large Uranian moons (see Uranus' natural satellites
Uranus' natural satellites
Uranus, the seventh planet of the Solar System, has 27 known moons, all of which are named after characters from the works of William Shakespeare and Alexander Pope. William Herschel discovered the first two moons, Titania and Oberon, in 1787, and the other spherical moons were discovered in 1851...

).

Miranda may have also once been in a 5:3 resonance with Ariel
Ariel (moon)
Ariel is the brightest and fourth-largest of the 27 known moons of Uranus. Ariel orbits and rotates in the equatorial plane of Uranus, which is almost perpendicular to the orbit of Uranus, and so has an extreme seasonal cycle....

, which would 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 Voyager 2
Voyager 2
The Voyager 2 spacecraft is a 722-kilogram space probe launched by NASA on August 20, 1977 to study the outer Solar System and eventually interstellar space...

flyby, was that a previous incarnation of Miranda was shattered by a massive impact, with the fragments reassembling and denser ones subsequently sinking to produce the current strange pattern.
Scientists recognize the following geological
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

 features on Miranda:
  • Craters
    Impact crater
    In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

  • Coronae
    Corona (planetary geology)
    In planetary geology, a corona is an oval-shaped feature. Coronae appear on both the planet Venus and Uranus's moon Miranda and may be formed by upwellings of warm material below the surface.-Coronae on Venus:...

     (large ovoid features)
  • Regiones (geological regions)
  • Rupes
    Rupes
    Rupes is the Latin word for 'cliff'. It is used in planetary geology to refer to escarpments on other planets, such as Mercury, and moons, such as Luna, Earth's natural satellite.How rupes are formed is, as of 2008, a matter of speculation...

     (scarp
    Escarpment
    An escarpment is a steep slope or long cliff that occurs from erosion or faulting and separates two relatively level areas of differing elevations.-Description and variants:...

    s)
  • Sulci
    Sulcus (geology)
    Sulcus is, in astrogeology, a long parallel groove on a planet or a moon.For example, Uruk Sulcus is a bright region of grooved terrain adjacent to Galileo Regio on Jupiter's moon Ganymede....

    (parallel grooves)

External links