![]() ![]() Something (probably incomplete arcs) definitely existed around Neptune, but the features of the ring system remained a mystery. Over the next six years, approximately 50 other occultations were observed with only about one-third of them yielding positive results. However, ground-based results were inconclusive. Neptune's next occultation, on 12 September 1983, resulted in a possible detection of a ring. In the 1980s, significant occultations were much rarer for Neptune than for Uranus, which lay near the Milky Way at the time and was thus moving against a denser field of stars. Later, after the Voyager fly-by, it was found that the occultation was due to the small Neptunian moon Larissa, a highly unusual event. On, they detected a dip in a star's brightness during one occultation however, the manner in which the star dimmed did not suggest a ring. Reitsema began searching for rings around Neptune. Soon after the Uranus discovery, a team from Villanova University led by Harold J. The first reliable detection of a ring was made in 1968 by stellar occultation, although that result would go unnoticed until 1977 when the rings of Uranus were discovered. However, his claim was never confirmed and it is likely that it was an observational artifact. The first mention of rings around Neptune dates back to 1846 when William Lassell, the discoverer of Neptune's largest moon, Triton, thought he had seen a ring around the planet. Rings of Neptune imaged by the James Webb Space Telescope's NIRCam instrument However, their stability is probably related to the resonant interaction between the Adams ring and its inner shepherd moon, Galatea. How the arcs are stabilized is still under debate. The arcs occupy a narrow range of orbital longitudes and are remarkably stable, having changed only slightly since their initial detection in 1980. Uniquely, the Adams ring includes five distinct arcs, named Fraternité, Égalité 1 and 2, Liberté, and Courage. The proportion of dust in the rings (between 20% and 70%) is high, while their optical depth is low to moderate, at less than 0.1. The rings of Neptune are made of extremely dark material, likely organic compounds processed by radiation, similar to those found in the rings of Uranus. Three other moons orbit between the rings: Naiad, Thalassa and Despina. Neptune also has a faint unnamed ring coincident with the orbit of the moon Galatea. Neptune's rings are named after astronomers who contributed important work on the planet: Galle, Le Verrier, Lassell, Arago, and Adams. At their densest, they are comparable to the less dense portions of Saturn's main rings such as the C ring and the Cassini Division, but much of Neptune's ring system is quite tenuous, faint and dusty, more closely resembling the rings of Jupiter. They were eventually imaged in 1989 by the Voyager 2 spacecraft. Hubbard's teams at La Silla Observatory (ESO) and at Cerro Tololo Interamerican Observatory in Chile. They were first discovered (as "arcs") by simultaneous observations of a stellar occultation on 22 July 1984 by André Brahic's and William B. The rings of Neptune consist primarily of five principal rings. Solid lines denote rings dashed lines denote orbits of moons. The scheme of Neptune's ring-moon system.
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