Caliban is the second-largest retrograde irregular satellite of

Uranus Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus (Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars), grandfather of Zeus (Jupiter) and father of Cronu ...

. It was discovered on 6 September 1997 by Brett J. Gladman,

Philip D. Nicholson Philip D. Nicholson (born 1951) is an Australian-born professor of astronomy at Cornell University in the Astronomy department specialising in Planetary Sciences. He has been editor-in-chief of the journal ''Icarus (journal), Icarus'' since 1998. ...

Joseph A. Burns Joseph Burns is a professor at Cornell University with a dual appointment in the Sibley School of Mechanical and Aerospace Engineering (MAE) and the Astronomy department. His primary area of research is dynamics in planetary sciences. Professio ...

, and John J. Kavelaars using the 200-inch

Hale telescope The Hale Telescope is a , 3.3 reflecting telescope at the Palomar Observatory in San Diego County, California, US, named after astronomer George Ellery Hale. With funding from the Rockefeller Foundation in 1928, he orchestrated the planning, de ...

together with

Sycorax Sycorax is an unseen character in William Shakespeare's play '' The Tempest'' (1611). She is a vicious and powerful witch and the mother of Caliban, one of the few native inhabitants of the island on which Prospero, the hero of the play, is s ...

and given the temporary designation S/1997 U 1. Designated Uranus XVI, it was named after the monster

character Character or Characters may refer to: Arts, entertainment, and media Literature * ''Character'' (novel), a 1936 Dutch novel by Ferdinand Bordewijk * ''Characters'' (Theophrastus), a classical Greek set of character sketches attributed to The ...

William Shakespeare William Shakespeare ( 26 April 1564 – 23 April 1616) was an English playwright, poet and actor. He is widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's natio ...

's play '' The Tempest''.

Orbit

Caliban follows a distant orbit, more than 10 times further from Uranus than the furthest regular moon

Oberon Oberon () is a king of the fairies in medieval and Renaissance literature. He is best known as a character in William Shakespeare's play ''A Midsummer Night's Dream'', in which he is King of the Fairies and spouse of Titania, Queen of the Fair ...

. Its orbit is retrograde, moderately

inclined Incline, inclined, inclining, or inclination may refer to: *Grade (slope), the tilt, steepness, or angle from horizontal of a topographic feature (hillside, meadow, etc.) or constructed element (road, railway, field, etc.) *Slope, the tilt, steepn ...

and slightly

eccentric Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off- center, in geometry * Eccentricity (graph theory) of a ...

. The

orbital parameters Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are considered in two-body systems using a Kepler orbit. There are many different ways to mathematically describe the same ...

suggest that it may belong to the same dynamic cluster as Stephano and

Francisco Francisco is the Spanish and Portuguese form of the masculine given name ''Franciscus''. Nicknames In Spanish, people with the name Francisco are sometimes nicknamed "Paco". San Francisco de Asís was known as ''Pater Comunitatis'' (father of ...

, suggesting common origin. TheIrregulars URANUS retro

The diagram illustrates the orbital parameters of the retrograde irregular satellites of Uranus (in polar co-ordinates) with the eccentricity of the orbits represented by the segments extending from the pericentre to the apocentre.

Physical characteristics

Caliban's diameter is estimated to be around 42 km, based on thermal measurements by the

Herschel Space Observatory The Herschel Space Observatory was a space observatory built and operated by the European Space Agency (ESA). It was active from 2009 to 2013, and was the largest infrared telescope ever launched until the launch of the James Webb Space Telesco ...

. Its albedo is estimated at around 0.22, which is unusually high compared to those of other Uranian irregular satellites. Neptune's largest irregular satellite,

Nereid In Greek mythology, the Nereids or Nereides ( ; grc, Νηρηΐδες, Nērēḯdes; , also Νημερτές) are sea nymphs (female spirits of sea waters), the 50 daughters of the ' Old Man of the Sea' Nereus and the Oceanid Doris, siste ...

, has a similarly high albedo as Caliban. Somewhat inconsistent reports put Caliban in ''light-red'' category ( , ), redder than Himalia but still less red than most

Kuiper belt The Kuiper belt () is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 t ...

objects. Caliban may be slightly redder than Sycorax. It also absorbs light at 0.7 μm, and one group of astronomers think this may be a result of liquid water that modified the surface. Measurements of Caliban's

light curve In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular frequ ...

by the

Kepler space telescope The Kepler space telescope is a disused space telescope launched by NASA in 2009 to discover Earth-sized planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched into an Earth-trailing heliocentric orbi ...

indicate that its rotation period is about 9.9 hours.

Origin

Caliban is hypothesized to be a captured object: it did not form in the accretionary disk that existed around Uranus just after its formation. The exact capture mechanism is not known, but capturing a moon requires the

dissipation In thermodynamics, dissipation is the result of an irreversible process that takes place in homogeneous thermodynamic systems. In a dissipative process, energy (internal, bulk flow kinetic, or system potential) transforms from an initial form ...

of energy. The possible capture processes include: gas drag in the

protoplanetary disk A protoplanetary disk is a rotating circumstellar disc of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star. The protoplanetary disk may also be considered an accretion disk for the star itself, ...

, many body interactions and the capture during the fast growth of the Uranus' mass (so-called "pull-down").

References

* * * *

External links

Caliban Profile
b
NASA's Solar System Exploration

(by Scott S. Sheppard)
MPC: Natural Satellites Ephemeris Service

(2005 Calvin J. Hamilton) {{DEFAULTSORT:Caliban (Moon) Moons of Uranus Irregular satellites 19970906 Moons with a retrograde orbit

Orbit

Physical characteristics

Origin

See also

References

External links