Wednesday, October 7, 2009

Lord of the Rings

In science news today, this just in: Saturn has yet another ring. Of course Saturn's primary rings are it's most well-known feature, this one is distinctly different in that it is far, far larger in scale, at an 8 million mile radius, or 50 times further out than the inner rings, and inclined roughly 27 degrees from them. The ring is very tenuous (some 20 particles per cubic km) and therefore difficult to detect in the visible light spectrum. One of the gas giant's farthest moons, Phoebe, orbits within the ring and scientists believe the gas and dust particles that comprise the ring originate from collisions between comets and Phoebe. I'd say that's a good guess if Phoebe's orbital plane matches that of the ring so maybe someone can look that up for me (I'm far too lazy myself).

One of the significances of this is that is that the presence of this large, diffuse ring of debris helps explain unusual albedo differential of the moon Iapetus. Astronomers earlier speculated a of causal relationship between Iapetus 'dark' side and the moon Phoebe, and the newly discovered ring material completes the inference. The picture of Iapetus from the Cassini probe clearly shows one side of the moon pitted with lower-albedo (that is, darker) surface material, this comes from material from the ring falling inward to the saturnian system and impacting the moon "like bugs on a windshield".

What I find fascinating is the sheer size of this structure. 'Ring' is kind of an understatement, it is more like a donut in that the thickness is several times the diameter of Saturn, which itself has a diameter some 11 times of Earth. It's an awesome discovery that really highlights the advances in astronomy that have been made in only a short time. And in space flight too, as a great deal of the data we have about Saturn comes from the probes we sent there. When I was a kid first reading about astronomy and the planets we knew Saturn had something like 17 moons. Now we know it has at least 60 and now this giant donut field of extra crap around it. It's obviously an important new (to us) part of Saturn's already complicated planetary system. It makes the Earth-moon system look positively quaint. Speaking of which, I wonder if some day we'll have our own ring from all the shit we've left up in near orbit.

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