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By John Weiss

John WeissWhen Galileo first observed Saturn’s rings with his improved telescope in 1610, he wasn’t sure what he was actually seeing. Even today, four hundred years and four spacecraft later, the rings hold many mysteries. How old are they? How long will they last? Why does Saturn appear to have such an extensive set of rings when the other giant planets have rings mostly made up of dust? What can rings teach us about how planets form? We can’t currently answer these deep questions, but we do know an awful lot about the rings, especially since we’ve never even seen a ring particle. In this upcoming webinar, Out of the Box Talks: How Are the Rings of Saturn Like a 155,000 Mile Diameter Granulator?, we’ll explore what we do know about the rings and how we think we know it.

7699_18471_1As a start, we’ll talk about measurements we have made and why they don’t tell us everything we wish to know. The immediate problem is that, as with particles being mixed in a granulator, it is impossible to directly observe the ring particles themselves as they collide and mix with each other. We are thus forced to use cruder proxy measurements to tease our quantities of interest. However, each of these measurements has drawbacks and can be “fooled” if the rings are not behaving as simply as we hope. (Spoiler alert: they’re not!)

Another tool we possess for understanding the rings is computer modeling. Using some basic physics, a bit of computational cleverness, and a lot of computer time, we can produce models showing how small patches of the rings evolve over short (a few to many days, typically) timescales. These models can be used to both understand the physics of the rings on larger scales as well as to determine properties of the ring particles that we can’t get other ways. However, these models, too, have their weaknesses.


This talk will focus on what we know about Saturn’s rings, how we think we know about them, and some of the cool, weird behaviors we see in the rings that you might not expect. As with most granular flows, including granulators, collective behavior of the particles often leads to counter-intuitive results that simple, fluid-based models would never predict! And, since this is astronomy, I promise a bunch of gorgeous pictures of Saturn and its rings to remind us all how amazing and fascinating this stuff is. This “out of the box” AAPS webinar is meant to be a fun discussion and coming together of minds from very different worlds (figuratively of course). Register today!

John Weiss, Ph.D., has been interested in astronomy since he found an old star-gazing guide in his grandmother’s house. Weiss is currently an assistant professor of physics at St. Martin’s University in Lacey, Wis., where he gets to teach intro physics as well classes on the history of science and upper-level mechanics and astrophysics.