Unraveling Saturn's Rings
The rings are made of fine particles and boulder-sized objects. The smallest particles may be just a few micrometers across while the largest bodies may only be a few meters. The first person to have suggested this composition is James Clerk Maxwell in 1859 and was confirmed by James Keeler through spectroscopic methods in 1895.
More recent studies revealed that Saturn’s rings are actually mostly made up of water ice with a little mixture of tholins and silicates, distributed in a minima/maxima arrangement. The rings do not have uniform density. Some, like Ring A and B, are much denser than others.
Much of the larger objects are found in the main rings: A, B, and C. The rest of the rings are mostly made up of dust particles, i.e., with radii of a few micrometers. The innermost, known as the D ring, is about 66,900 km from Saturn, while the outermost, known as the Phoebe Ring, is about 13,000,000 km away.
The Phoebe Ring is invisible when viewed using visible light. Although its existence was predicted way back in 1970 by Steven Soter, it was only discovered very recently (in 2009) using infrared wavelengths through the Spitzer Space Telescope. This invisible ring stretches across the vast expanse of space around Saturn. In fact, its thickness alone is already 20 times Saturn’s diameter.
Another ring that’s hard to make out is the Janus/Epimetheus Ring, which occupies the neighborhood of Janus’ and Epimetheus’ orbits. Janus and Epimetheus are two moons of Saturn that were once mistaken as one celestial body. This was because the two moons traverse practically the same orbital path.
The main rings have distinguishable gaps in them. For example, the A ring, which is the outermost of the main rings contains the Encke Gap and the Keeler Gap. The Encke Gap is 325 km wide and is caused by the presence of Pan, one of Saturn’s natural satellites. Keeler Gap, on the other hand, is only 42 km wide and is caused by another moon, Daphnis.
Saturns Rings, although not visible through the naked eye, are among the favorite objects of amateur astronomers.
In 2008, Saturn’s rings seemed to be gradually disappearing. Read about that story here in Universe Today. Just click that link. Here’s another one that may interest you: Saturn’s rings have gone plaid.
NASA has a breathtaking image of Saturn’s rings. Want to see an image depicting Saturn’s invisible infrared ring?
Tired eyes? Let your ears help you learn for a change. Here are some episodes from Astronomy Cast that just might suit your taste:
The End of the Universe Part 2: The End of Everything
Questions on the Size, Shape and Centre of the Universe
Reference:
NASA: Saturnian Rings Fact Sheet
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