Appearances can be deceiving - Saturn’s rings continue to surprise scientists

It seems intuitive that an opaque material should contain more stuff than a more translucent substance. For example, muddier water has more suspended particles of dirt in it than clearer water. Likewise, you might think that, in the rings of Saturn, more opaque areas contain a greater concentration of material than places where the rings seem more transparent.

But this intuition does not always apply, according to a recent study of the rings using data from NASA's Cassini mission. In their analysis, scientists found surprisingly little correlation between how dense a ring might appear to be -- in terms of its opacity and reflectiveness -- and the amount of material it contains.

The new results concern Saturn's B ring, the brightest and most opaque of Saturn's rings, and are consistent with previous studies that found similar results for Saturn's other main rings.

The scientists found that, while the opacity of the B ring varied by a large amount across its width, the mass – or amount of material – did not vary much from place to place. They "weighed" the nearly opaque center of the B ring for the first time -- technically, they determined its mass density in several places -- by analyzing spiral density waves. These are fine-scale ring features created by gravity tugging on ring particles from Saturn's moons, and the planet's own gravity. The structure of each wave depends directly on the amount of mass in the part of the rings where the wave is located.

Research on the mass of Saturn's rings has important implications for their age. A less massive ring would evolve faster than a ring containing more material, becoming darkened by dust from meteorites and other cosmic sources more quickly. Thus, the less massive the B ring is, the younger it might be -- perhaps a few hundred million years instead of a few billion.

Source & further reading:http://www.nasa.gov/feature/jpl/saturns-rings-less-than-meets-the-eye

Photo: Saturn's B ring is the most opaque of the main rings, appearing almost black in this Cassini image taken from the unlit side of the ringplane.
Credits: NASA/JPL-Caltech/Space Science Institute