Neptune possesses a set of five rings. William Lassell was the first to have thought of it but the idea was not further explored. The first official detection was made in 1983 during a stellar occultation from Earth. Exploration was then initiated by Voyager 2 in 1989 and images made by the explorers confirmed the issue. The rings that made up the system were vague, dusty and faint.
The rings of Neptune consist of very dark material which can be compared to organic compounds processed by radiation. The composition could include ice. The rings were found similar to those of Uranus. The rings have huge quantities of dust and the proportion was between 20 and 70%, almost similar to Jupiterian rings which contain 50%-100% of dust. The rings are red in color, transparent and thin. Their normal optical depths are low and are less than 0.1. It is believed that the rings of Neptune are younger than the age of the Solar System itself.
The five rings of Neptune were distinct and clear in the images taken by Voyager 2. In order of decreasing distance from Neptune, the names of the Neptunian rings are Adams, Arago, Lassell, Leverrier and Galle â€“ the names of astronomers who contributed to the discovery and study of the planet. A sixth unnamed ring intervenes with the orbit of Galatea,one of Neptuneâ€™s moons. Theother three moons, Thalassa, Despina ad Naiad orbit freely between Galle(innermost) and Leverrier(second from planet).
The outermost ring, Adams, is divided into 5 bright arcs, namely FraternitÃ©,Egalite 1 and 2, LibertÃ©, and Courage. The first three names were taken from the words â€˜fraternityâ€™, equality and liberty, after the motto of the French Revolution. They occupy a small range of orbital longitudes and have only just moved slightly from their initial position in 1980. Scientists debated on how these arcs remain as they are, for the reason that the arcs should have spread out in uniform manner overtime as predicted by the law of motion. Neptuneâ€™s moon Galatea, just inside the ring, is now believed to affect the confinement ofthe arcs.
The rings of Neptune are well-defined. LeVerrier, Arago and Adam are narrow,with widths of about 100km or less. The other two are broad. They are between2000 and 5000km wide. The innermost ring was named after the man who first saw the planet through a telescope, Johann Gottfried Galle. This ring is faint, has a depth of .15km and an optical depth of 10-4. Dust composition is between 40 to 70%.
The second ring got its name from Urbain Le Verrier, who predicted Neptuneâ€™s position through mathematical equations in 1846. The radius of its orbit is about 53,200km but has a width of about 113km. The amount of dust present in the Leverrier ring is between 40 to 70%. The moon Despina which just orbits inward the ring could be guiding it to be confine.
The Lassell, also called â€˜plateauâ€™ ring, is the broadest ring of all the five Neptunian rings. It is named after William Lassell who discovered Neptuneâ€™s largest moon. The Arago ring, positioned next to the outermost ring is seen as a thin band of light. It is named after Francois Arago, a French, Mathematician, Scientist and Politician.