Caliban (moon)
Encyclopedia
Retrograde motion
Retrograde motion is motion in the direction opposite to the movement of something else, and is the contrary of direct or prograde motion. This motion can be the orbit of one body about another body or about some other point, or the rotation of a single body about its axis, or other phenomena such...
irregular
Irregular satellite
In astronomy, an irregular moon is a natural satellite following a distant, inclined, and often eccentric and retrograde orbit. They are believed to have been captured by their parent planet, unlike regular satellites, which form in situ....
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....
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...
. It was discovered on 6 September 1997 by Brett J. Gladman
Brett J. Gladman
Brett J. Gladman is a Canadian astronomer and a full professor at the University of British Columbia's Department of Physics and Astronomy in Vancouver, British Columbia. He holds the Canada Research Chair in Planetary Astronomy.-Career:...
, Philip D. Nicholson
Phil Nicholson
Philip D. Nicholson is a Professor of Astronomy at Cornell University in the Astronomy department specialising in Planetary Sciences. He was part of the team led by Brett J. Gladman that discovered several moons of Uranus and Saturn. He has been editor-in-chief of the journal Icarus since 1998.-...
, Joseph A. Burns
Joseph A. Burns
Joseph Burns is a professor at Cornell University with a dual appointment in the Department of Theoretical and Applied Mechanics and the Astronomy department. His primary area of research is dynamics in planetary sciences.- Professional biography :...
, and John J. Kavelaars
John J. Kavelaars
John J. Kavelaars, better known as JJ Kavelaars, is a Canadian astronomer who was part of a team that discovered several moons of Jupiter, Saturn, Uranus, and Neptune....
using the 200-inch Hale telescope
Hale telescope
The Hale Telescope is a , 3.3 reflecting telescope at the Palomar Observatory in California, named after astronomer George Ellery Hale. With funding from the Rockefeller Foundation, he orchestrated the planning, design, and construction of the observatory, but did not live to see its commissioning...
together with Sycorax
Sycorax (moon)
Sycorax is the largest retrograde irregular satellite of Uranus. Sycorax was discovered on 6 September 1997 by Brett J. Gladman, Philip D. Nicholson, Joseph A. Burns, and John J...
and given the temporary designation S/1997 U 1.
Designated Uranus XVI, it was named after the monster character
Caliban (character)
Caliban is one of the primary antagonists in William Shakespeare's play The Tempest.- Character :Caliban is forced into servitude on an island ruled by Prospero. While he is referred to as a calvaluna or mooncalf, a freckled monster, he is the only human inhabitant of the island that is otherwise...
in 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.
Orbit
Caliban follows a distant orbit, more than 10 times further from Uranus than the furthest regular moon OberonOberon (moon)
Oberon , also designated ', is the outermost major moon of the planet Uranus. It is the second largest and second most massive of the Uranian moons, and the ninth most massive moon in the Solar System. Discovered by William Herschel in 1787, Oberon is named after the mythical king of the fairies...
. Its orbit is retrograde, moderately inclined
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...
and slightly eccentric. The orbital parameters suggest that it may belong to the same dynamic cluster as Stephano
Stephano (moon)
Stephano is a retrograde irregular satellite of Uranus. It was discovered by Brett J. Gladman, et al. in 1999, and given the provisional designation S/1999 U 2....
and Francisco
Francisco (moon)
Francisco is the innermost irregular satellite of Uranus.Francisco was discovered by Matthew J. Holman, et al. and Brett J. Gladman, et al. in 2003 from pictures taken in 2001 and given the provisional designation S/2001 U 3....
, suggesting common origin.
The diagram illustrates the orbital parameters of the retrograde irregular satellite
Irregular satellite
In astronomy, an irregular moon is a natural satellite following a distant, inclined, and often eccentric and retrograde orbit. They are believed to have been captured by their parent planet, unlike regular satellites, which form in situ....
s of Uranus (in polar co-ordinates) with the eccentricity of the orbits represented by the segments extending from the pericentre
Apsis
An apsis , plural apsides , is the point of greatest or least distance of a body from one of the foci of its elliptical orbit. In modern celestial mechanics this focus is also the center of attraction, which is usually the center of mass of the system...
to the apocentre
Apsis
An apsis , plural apsides , is the point of greatest or least distance of a body from one of the foci of its elliptical orbit. In modern celestial mechanics this focus is also the center of attraction, which is usually the center of mass of the system...
.
Physical characteristics
Its diameter is estimated at 72 km (assuming albedoAlbedo
Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...
of 0.04) making it the second largest irregular satellite of Uranus, half the size of Sycorax
Sycorax (moon)
Sycorax is the largest retrograde irregular satellite of Uranus. Sycorax was discovered on 6 September 1997 by Brett J. Gladman, Philip D. Nicholson, Joseph A. Burns, and John J...
, the biggest irregular satellite of Uranus.
Somewhat inconsistent reports put Caliban in light-red category ( , ), redder than Himalia
Himalia (moon)
Himalia is the largest irregular satellite of Jupiter, the sixth largest overall in size, and the fifth largest in mass. It was discovered by Charles Dillon Perrine at the Lick Observatory on 3 December 1904 and is named after the nymph Himalia, who bore three sons of Zeus .- Discovery...
but still less red than most Kuiper belt
Kuiper belt
The Kuiper belt , sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune to approximately 50 AU from the Sun. It is similar to the asteroid belt, although it is far larger—20 times as wide and 20 to 200 times as massive...
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.
The light curve
Light curve
In astronomy, a light curve is a graph of light intensity of a celestial object or region, as a function of time. The light is usually in a particular frequency interval or band...
suggests the rotation period of Caliban is about 2.7h.
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 dissipationDissipation
In physics, dissipation embodies the concept of a dynamical system where important mechanical models, such as waves or oscillations, lose energy over time, typically from friction or turbulence. The lost energy converts into heat, which raises the temperature of the system. Such systems are called...
of energy. The possible capture processes include: gas drag in the protoplanetary disk
Protoplanetary disk
A protoplanetary disk is a rotating circumstellar disk of dense gas surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star...
, many body interactions and the capture during the fast growth of the Uranus' mass (so-called "pull-down").
External links
- Caliban Profile by NASA's Solar System Exploration
- David Jewiit pages
- Uranus' Known Satellites (by Scott S. SheppardScott S. SheppardScott S. Sheppard is an astronomer in the Department of Terrestrial Magnetism at the Carnegie Institution for Science. Starting as a graduate student at the Institute for Astronomy at the University of Hawaii, he was credited with the discovery of many small moons of Jupiter, Saturn, Uranus, and...
) - MPC: Natural Satellites Ephemeris Service
- Caliban and Sycorax, Moons of Uranus (2005 Calvin J. Hamilton)