Ophelia is one of the inner moons of Uranus. It was discovered by the Voyager 2 spacecraft on January 20, 1986, from images taken during its flyby of the planet. It is named after Ophelia, a character in William Shakespeare's play Hamlet. Along with Cordelia, Ophelia serves as a shepherd moon for Uranus's brightest ring, the Epsilon ring.
Discovery and Naming
Ophelia was discovered by astronomer Richard Terrile from images captured by the Voyager 2 spacecraft during its encounter with Uranus. Upon its discovery, it was temporarily designated S/1986 U 8. It was later officially named Ophelia, in line with the convention of naming Uranian moons after characters from the works of William Shakespeare or Alexander Pope.
Physical Characteristics
Ophelia is a small, irregularly shaped moon, with an estimated mean diameter of approximately 53 kilometers (33 miles). Due to the limited resolution of Voyager 2's images, its exact shape and surface features are not well-known. Like other inner Uranian moons, its surface is likely dark and heavily cratered, suggesting a composition primarily of water ice with some rocky material. Its low mass results in very weak surface gravity.
Orbit and Relationship to Rings
Ophelia orbits Uranus at an average distance of about 53,760 kilometers (33,400 miles) from the planet's center, well within the planet's intricate ring system. It is dynamically linked to the Epsilon ring, the brightest and outermost of Uranus's narrow rings. Ophelia functions as the outer shepherd moon for the Epsilon ring, meaning its gravitational influence helps to confine the particles within the ring, preventing them from scattering into space. Its companion inner moon, Cordelia, acts as the inner shepherd moon for the Epsilon ring, further stabilizing the ring's structure. Ophelia and Cordelia are thought to constantly perturb each other gravitationally, leading to slight variations in their orbits over time.
Observation and Exploration
Due to its small size and considerable distance from Earth, Ophelia has only been observed directly by the Voyager 2 spacecraft during its brief flyby of Uranus in 1986. Subsequent observations by the Hubble Space Telescope and various ground-based telescopes have primarily focused on larger, brighter Uranian moons or the planet itself, making detailed study of Ophelia extremely challenging. No future space missions are currently planned that would provide more detailed images or data of Ophelia.
See Also
- Moons of Uranus
- Cordelia (moon)
- Rings of Uranus
- Voyager 2