Trinculo, also known as Uranus XXI and previously as S/2001 U 1, is a small

irregular satellite In astronomy, an irregular moon, irregular satellite, or irregular natural satellite is a natural satellite following an orbit that is irregular in some of the following ways: Distant; inclined; highly elliptical; retrograde. They have often be ...

or moon of

Uranus Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a Supercritical fluid, supercritical phase of matter, which astronomy calls "ice" or Volatile ( ...

, orbiting in the retrograde direction. It was discovered on 13 August 2001 by Matthew J. Holman,

John J. Kavelaars J-John Kavelaars, better known as JJ Kavelaars (born 1966), is a Canadian astronomer who was part of a team that discovered several moons of Jupiter, Saturn, Uranus, and Neptune. He is also a discoverer of minor planets and an investigator on the ...

, and Dan Milisavljevic using the 4.0-meter

Víctor M. Blanco Telescope The Víctor M. Blanco Telescope, also known as the Blanco 4m, is a 4-metre aperture telescope located at the Cerro Tololo Inter-American Observatory, Chile on the summit of Mt. Cerro Tololo. Commissioned in 1974 and completed in 1976, the telescop ...

Cerro Tololo Observatory The Cerro Tololo Inter-American Observatory (CTIO) is an astronomical observatory located on the summit of Mt. Cerro Tololo in the Coquimbo Region of northern Chile, with additional facilities located on Mt. Cerro Pachón about to the southeas ...

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

. It was named after Trinculo, a

jester A jester, also known as joker, court jester, or fool, was a member of the household of a nobleman or a monarch kept to entertain guests at the royal court. Jesters were also travelling performers who entertained common folk at fairs and town ma ...

from

William Shakespeare William Shakespeare ( 23 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 nation ...

's play ''

The Tempest ''The Tempest'' is a Shakespeare's plays, play by William Shakespeare, probably written in 1610–1611, and thought to be one of the last plays that he wrote alone. After the first scene, which takes place on a ship at sea during a tempest, th ...

''. Trinculo orbits Uranus at an average distance of and takes about 749 Earth days (2.1 Earth years) to complete one orbit. Trinculo is estimated to be about in diameter and its surface might be dark and gray in color.

Discovery

Trinculo was discovered on 13 August 2001 by a group of astronomers consisting of Matthew J. Holman,

, and Dan Milisavljevic, who at the time were searching for distant

moons of Uranus Uranus, the seventh planet of the Solar System, has 28 confirmed moons. The 27 with names are named after characters that appear in, or are mentioned in, William Shakespeare's plays and Alexander Pope's poem '' The Rape of the Lock''. Uranus's ...

. Trinculo was the sixth irregular moon discovered around Uranus. The discovery observations were made at

, using the 4.0-m

equipped with a wide-field camera. The group discovered Trinculo and three other Uranian irregular moons (

Francisco Francisco is the Spanish and Portuguese form of the masculine given name ''Franciscus''. Meaning of the name Francisco In Spanish, people with the name Francisco are sometimes nicknamed "Paco (name), Paco". Francis of Assisi, San Francisco de A ...

Ferdinand Ferdinand is a Germanic name composed of the elements "journey, travel", Proto-Germanic , abstract noun from root "to fare, travel" (PIE , "to lead, pass over"), and "courage" or "ready, prepared" related to Old High German "to risk, ventu ...

, and

Margaret Margaret is a feminine given name, which means "pearl". It is of Latin origin, via Ancient Greek and ultimately from Iranian languages, Old Iranian. It has been an English language, English name since the 11th century, and remained popular thro ...

) in the telescope images by using a computer algorithm that followed the motion of Uranus and then combined the images to enhance the faint moons—a technique known as shift-and-adding. Later images obtained by Kavelaars using the

Canada–France–Hawaii Telescope The Canada–France–Hawaii Telescope (CFHT) is located near the summit of Mauna Kea mountain on Hawaii's Big Island at an altitude of 4,204 meters (13,793 feet), part of the Mauna Kea Observatory. Operational since 1979, the telescope is a Pri ...

on 25 August 2001 confirmed that Trinculo was orbiting Uranus. To determine the orbit of Trinculo, the group continued observing the moon from different observatories, including 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 ...

Palomar Observatory The Palomar Observatory is an astronomical research observatory in the Palomar Mountains of San Diego County, California, United States. It is owned and operated by the California Institute of Technology (Caltech). Research time at the observat ...

and 8.2-m

Very Large Telescope The Very Large Telescope (VLT) is an astronomical facility operated since 1998 by the European Southern Observatory, located on Cerro Paranal in the Atacama Desert of northern Chile. It consists of four individual telescopes, each equipped with ...

(VLT) at

Paranal Observatory Paranal Observatory is an astronomical observatory operated by the European Southern Observatory (ESO). It is located in the Atacama Desert of Northern Chile on Cerro Paranal at altitude, south of Antofagasta. By total light-collecting area, ...

. Brian G. Marsden, director of the

Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Funct ...

, helped compute the orbit of Trinculo and provided predictions for its location in 2002. Marsden's predictions allowed Gladman to identify a Uranian moon candidate detected in VLT images taken by Philippe Rousselot and Olivier Mousis on 5 September 2002, which was then confirmed to be Trinculo after Gladman and

Tommy Grav This is a list of minor-planet discoverers credited by the Minor Planet Center with the discovery of one or several minor planets (such as near-Earth and main-belt asteroids, Jupiter trojans and distant objects). , the discovery of 612,011 num ...

investigated images taken earlier by the Blanco telescope on 13 August 2002. The Minor Planet Center announced the discovery of Trinculo on 30 September 2003.

Name

When the discovery of Trinculo was announced, it was given the temporary

provisional designation Provisional designation in astronomy is the naming convention applied to astronomical objects immediately following their discovery. The provisional designation is usually superseded by a permanent designation once a reliable orbit has been calcu ...

S/2001 U 1 by the Minor Planet Center. It was later named and given the

Roman numeral designation The naming of moons has been the responsibility of the International Astronomical Union's committee for Planetary System Nomenclature since 1973. That committee is known today as the Planetary nomenclature, Working Group for Planetary System Nomenc ...

Uranus XXI by the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

Working Group for Planetary System Nomenclature The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

on 29 December 2005. The moon was named after the drunken

Trinculo from

's play, ''

''.

Orbit

Trinculo is an

irregular moon In astronomy, an irregular moon, irregular satellite, or irregular natural satellite is a natural satellite following an orbit that is irregular in some of the following ways: Distant; inclined; highly elliptical; retrograde. They have often be ...

of Uranus, which have very wide, elliptical, and inclined orbits in contrast to the

regular moon In astronomy, a regular moon or a regular satellite is a natural satellite following a relatively close, stable, and circular orbit which is generally aligned to its primary's equator. They form within discs of debris and gas that once surroun ...

s of Uranus. Irregular moons like Trinculo are thought to be former

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

s that were captured by their planet during the Solar System's formation. The Uranian irregular moons are loosely bound by Uranus's gravity because of their great distance from the planet, so their orbits are frequently perturbed by the gravity of the Sun and other planets. This results in significant changes in the orbits of irregular moons over short periods of time, so a simple Keplerian elliptical orbit cannot accurately describe the long-term orbital motions of irregular moons. Instead, proper or mean orbital elements are used to describe the long-term orbits of irregular moons more accurately, since these are calculated by averaging out the perturbed orbit over a long period of time. Over a 10,000-year time period, Trinculo's average

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longe ...

or orbital distance from Uranus is , with an average

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...

of . Trinculo has an average

orbital eccentricity In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values be ...

of 0.22 and an average

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

of 167° with respect to the

ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. Fr ...

, or the plane of Earth's orbit. Since Trinculo's orbital inclination is greater than 90°, the moon has a

retrograde orbit Retrograde motion in astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its primary, that is, the central object (right figure). It may also describe other motions such as precession or ...

, meaning it orbits in the opposite direction of Uranus' orbit around the Sun. Trinculo's orbital elements fluctuate over time due to perturbations: its semi-major axis varies by up to ±, eccentricity varies by ±0.02, and inclination varies by ±1°. Trinculo's orbit exhibits

nodal Nodal may refer to: * Nodal, the adjectival form of the noun :wikt:node * Nodal homolog, a protein encoded by the gene NODAL and responsible for left-right asymmetry * Nodal (software), a novel music composition program * Christian Nodal ( ...

and

apsidal precession In celestial mechanics, apsidal precession (or apsidal advance) is the precession (gradual rotation) of the line connecting the apsis, apsides (line of apsides) of an orbiting body, astronomical body's orbit. The apsides are the orbital poi ...

with average periods of several thousand Earth years. The eccentric orbits of Trinculo and other Uranian irregular moons overlap in distance, which leads to the possibility of Trinculo passing close to another irregular moon. Orbit simulations performed by

Marina Brozović A marina (from Spanish , Portuguese and Italian : "related to the sea") is a dock or basin with moorings and supplies for yachts and small boats. A marina differs from a port in that a marina does not handle large passenger ships or cargo fro ...

and Robert Jacobson in 2022 found that Trinculo had approached

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 (character), Caliban, one of the few native inhabitants of the island on which Prospero, the he ...

within several tens of thousands of kilometers 9,700 years ago. Trinculo is not known to be part of a

collisional family In astronomy, a collisional family is a group of objects that are thought to have a common origin in an impact (collision). They have similar compositions and most share similar orbital elements. Known or suspected collisional families include nu ...

or group; its orbit is apparently unique among the known Uranian irregular moons. If there is a collisional family associated with Trinculo, then any Uranian irregular moons related to it are likely undiscovered because they are presumably small and faint. File:Animation of Sycorax orbit around Uranus.gif, Animation of Trinculo's orbit (green) around Uranus.
File:Irregular moon orbits a vs. i.jpg, Irregular satellites of all four giant planets, plotted by average distance from their planet (

in Hill radii) and

orbital inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Earth ...

(in

degrees Degree may refer to: As a unit of measurement * Degree (angle), a unit of angle measurement ** Degree of geographical latitude ** Degree of geographical longitude * Degree symbol (°), a notation used in science, engineering, and mathematics ...

wrt

). Data as of February 2024.

Physical characteristics

Trinculo is very faint with an average

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

of 25.4, so it could only be observed with long- exposure imaging by large-

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

telescopes. Trinculo is expected to have a dark surface composed of water ice,

hydrate In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understo ...

silicates A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used for an ...

, and

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

s, similar to other irregular moons. Observations by the ''Herschel'' space telescope did not find any significant

infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

thermal emission Thermal radiation is electromagnetic radiation emitted by the thermal motion of particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation. The emission of energy arises from a combination of electro ...

coming from Trinculo, indicating the moon must have a

geometric albedo In astronomy, the geometric albedo of a celestial body is the ratio of its actual brightness as seen from the light source (i.e. at zero phase angle (astronomy), phase angle) to that of an ''idealized'' flat, fully reflecting, diffuse reflection, d ...

higher than 0.03 and a diameter smaller than . Assuming an absolute magnitude of 12.7 and a generic irregular moon geometric albedo range of 0.04–0.10, Trinculo should have a diameter between .

Scott Sheppard Scott Sander Sheppard (born 1977) is an American astronomer and a discoverer of numerous moons, comets and minor planets in the outer Solar System. He is an astronomer in the Department of Terrestrial Magnetism at the Carnegie Institution for S ...

, who has discovered many irregular moons around other giant planets, estimates Trinculo's diameter to be . Observations by the Keck II telescope in 2003 suggest that Trinculo might have a "neutral" or gray color, similar to the larger Uranian irregular moons

Prospero Prospero ( ) is a fictional character and the protagonist of William Shakespeare's ''The Tempest''. Character Twelve years before the play begins, Prospero is usurped from his position as the rightful Duke of Milan by his brother Antonio, ...

and

Setebos Setebos (also Settaboth) was a deity of the Tehuelche people of eastern Patagonia. The name was recorded by Europeans traveling with Ferdinand Magellan during the first circumnavigation of the world (1519–1522), and again some 58 years later b ...

. Astronomers have attempted to measure Trinculo's

rotation period In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the objec ...

in 2005 by using the Very Large Telescope, but were unable to find any periodic variation in the moon's brightness.

Exploration

Trinculo has not been imaged up close by a

space probe Uncrewed spacecraft or robotic spacecraft are spacecraft without people on board. Uncrewed spacecraft may have varying levels of autonomy from human input, such as remote control, or remote guidance. They may also be autonomous, in which th ...

. However, Trinculo and other Uranian irregular moons are planned to be distant observation targets for the upcoming

Uranus Orbiter and Probe The Uranus Orbiter and Probe is an orbiter mission concept to study Uranus and its moons. The orbiter would also deploy an atmospheric probe to characterize Uranus's atmosphere. The concept is being developed as a potential large strategic sci ...

(UOP), which will measure the Uranian irregular moons' rotation periods and shapes by watching their brightness change over time. The UOP may not be able to do a close flyby of Trinculo because the moon does not orbit near the ecliptic plane.

Notes

References

External links

Uranus Moons – Trinculo

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

Science, 25 January 2024
Tracking of S/2001 U 1
Brett Gladman, October 2002
Three more minor moons for Uranus
J. J. Kavelaars, 27 November 2001
Moons of Uranus
Scott S. Sheppard,

Carnegie Institution for Science The Carnegie Institution for Science, also known as Carnegie Science and the Carnegie Institution of Washington, is an organization established to fund and perform scientific research in the United States. This institution is headquartered in W ...

{{DEFAULTSORT:Trinculo (Moon) Moons of Uranus Irregular satellites Discoveries by Matthew J. Holman Discoveries by John J. Kavelaars 20010813 Moons with a retrograde orbit The Tempest