Trinculo (moon)

Lore & Background

Trinculo was discovered on 13 August 2001 by a group of astronomers searching for distant moons of Uranus. The discovery observations were made at Cerro Tololo Observatory, Chile, using the 4.0-m Víctor M. Blanco Telescope equipped with a wide-field camera. The group identified Trinculo and three other Uranian irregular moons (Francisco, Ferdinand, and Margaret) in 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 on 25 August 2001 confirmed that Trinculo was orbiting Uranus. To determine the orbit, the group continued observing from different observatories, including the 200-inch Hale Telescope at Palomar Observatory and 8.2-m Very Large Telescope (VLT) at Paranal Observatory. Brian G. Marsden helped compute the orbit and provided predictions for its location in 2002, which allowed Gladman to identify a Uranian moon candidate detected in VLT images taken by Philippe Rousselot and Olivier Mousis on 5 September 2002, confirmed to be Trinculo after Gladman and Tommy Grav investigated images taken earlier by the Blanco telescope on 13 August 2002. The Minor Planet Center announced the discovery on 30 September 2003. Trinculo was named after the drunken jester Trinculo from William Shakespeare's play The Tempest. In a 2014 interview with the Folger Shakespeare Library, Kavelaars remarked that he picked the name because his team was 'drunk with power' and that Trinculo's irregular orbit resembled a wandering drunken sailor. The moon was given the Roman numeral designation Uranus XXI by the International Astronomical Union's Working Group for Planetary System Nomenclature on 29 December 2005. Trinculo is an irregular moon of Uranus, thought to be a former asteroid captured during the Solar System's formation. Its orbit is retrograde, meaning it orbits in the opposite direction of Uranus' orbit around the Sun. Over a 10,000-year time period, Trinculo's average semi-major axis is 8.05 million km, with an average orbital period of 2.05 years, an average eccentricity of 0.22, and an average inclination of 167° with respect to the ecliptic. Its orbital elements fluctuate due to perturbations: semi-major axis varies by up to ±12,200 km, eccentricity by ±0.02, and inclination by ±1°. Orbit simulations performed by Marina Brozović and Robert Jacobson in 2022 found that Trinculo had approached Sycorax within several tens of thousands of kilometers 9,700 years ago. Trinculo is not known to be part of a collisional family or group; its orbit is apparently unique among the known Uranian irregular moons.

Reader's Guide

Trinculo is notable as one of the six irregular moons of Uranus discovered in 2001, representing a class of distant, loosely bound satellites thought to be captured asteroids. Its discovery highlighted the effectiveness of shift-and-add imaging techniques for finding faint objects. The moon's orbit is highly perturbed by the Sun and other planets, causing significant changes over short periods, so its long-term motion is described using averaged proper orbital elements rather than simple Keplerian ellipses. Trinculo's orbit overlaps in distance with other Uranian irregular moons, leading to potential close approaches, such as the one with Sycorax 9,700 years ago. Physically, Trinculo is very faint (apparent magnitude 25.4) and estimated to be about 18 km in diameter, with a dark, possibly gray surface. Observations by the Herschel space telescope set an upper limit on its diameter of 50 km and a lower limit on its geometric albedo of 0.03. Astronomers attempted to measure its rotation period in 2005 using the Very Large Telescope but found no periodic brightness variation. Trinculo has not been imaged up close by a space probe; all Uranian irregular moons are planned as distant observation targets for the proposed Uranus Orbiter and Probe, though a close flyby may not be possible because Trinculo does not orbit near the ecliptic plane.

Did You Know?

• Trinculo was the sixth irregular moon discovered around Uranus.
• Its name comes from a drunken jester in Shakespeare's The Tempest, chosen because the moon's irregular orbit resembled a wandering drunken sailor.
• Trinculo's average orbital inclination is 167°, making its orbit retrograde.
• The moon's discovery was announced on 30 September 2003, over two years after the initial observations.