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Astronomy Cast Episode 195 from Monday, June 21, 2010.

Welcome to Astronomy Cast, our weekly facts based journey through the cosmos, where we help you understand not only what we know, but how we know what we know.

My name is Fraser Kane, I'm the publisher of University Day, and with me is Dr. Pamela Gaia Professor at Southern Illinois University Everest Falls.

Pamela, how are you doing? I'm doing well, and thank you so much for being a morning person.

This is one of those times where cramming recording in between all my travel and your kids' summer breaks.

Yeah, I think I woke up four minutes ago, but I'm going to go.

Okay, so Saturn is best known for its rings. This huge and beautiful planetary ring system is easy to spot in even the smallest backyard telescope.

So you can imagine they were surprised when Galileo first noticed them, but astronomers have gone on to find rings around the other gas giant worlds in the solar system.

The differences are surprising.

All right, so let's start and tell the story of Saturn's rings, because I think it's quite funny.

Well, so poor Galileo, he has a telescope. He's using it to look up rather than looking for enemy vessels coming over the horizon, which was its original marketed purpose.

And when he looks at Saturn because his telescope just isn't that good, it kind of looks like a very symmetric teapot, a big circle in the center with two handles off to the side.

One of his original interpretations was he thought it was actually three planets that were somewhat bound together in the ecliptic.

Like a planet with ears.

Yeah, exactly.

And that was just because his telescope just wasn't good enough to really figure it out.

And I guess he, I mean, when you or I look through a small, even through the Galileo scope, right, we see the same thing, but we know we're seeing.

And so we're like, oh, look, you can see the rings. But if you have no idea what you're looking at, you can imagine your brain is trying to wrap your head around this funny shape.

Well, it's this ball with ears.

And making it even worse, one of the things that we saw just last year actually is, as Saturn orbits, the angle at which we see its rings changes, where sometimes they seem to form a hula hoop all the way around Saturn allowing you to see the gap between Saturn and its rings all the way around the planet.

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