Possible Ring System Around Rhea
Saturn's second largest moon Rhea has been hypothesized to have a tenuous ring system of its own consisting of three narrow bands embedded in a disk of solid particles. These putative rings have not been imaged, but their existence has been inferred from Cassini observations in November 2005 of a depletion of energetic electrons in Saturn's magnetosphere near Rhea. The Magnetospheric Imaging Instrument (MIMI) observed a gentle gradient punctuated by three sharp drops in plasma flow on each side of the moon in a nearly symmetric pattern. This could be explained if they were absorbed by solid material in the form of an equatorial disk containing denser rings or arcs, with particles perhaps several decimetres to approximately a metre in diameter. A more recent piece of evidence consistent with the presence of Rhean rings is a set of small ultraviolet-bright spots distributed in a line that extends three quarters of the way around the moon's circumference, within 2 degrees of the equator. The spots have been interpreted as the impact points of deorbiting ring material. However, targeted observations by Cassini of the putative ring plane from several angles have turned up nothing, suggesting that another explanation for these enigmatic features is needed.
Read more about this topic: Rings Of Saturn
Famous quotes containing the words ring and/or system:
“I like well the ring of your last maxim, “It is only the fear of death makes us reason of impossibilities.” And but for fear, death itself is an impossibility.”
—Henry David Thoreau (1817–1862)
“We are now going through a period of demolition. In morals, in social life, in politics, in medicine, and in religion there is a universal upturning of foundations. But the day of reconstruction seems to be looming, and now the grand question is: Are there any sure and universal principles that will evolve a harmonious system in which we shall all agree?”
—Catherine E. Beecher (1800–1878)