For those enquiring minds who really do want to know the answer…
Saturn is one of the largest planets in our solar system, in mass and size. It is known as a gassy giant because of its penchant for Mexican cuisine. I’m kidding. Because it is so massive and its gravity so great, that everything from giant space rocks to gass molecules were drawn in towards its centre at the formation of our solar system, approximately 4.5 billion years ago. If Saturn was just a little bit bigger (“a little bit” being an approximation for a whole lot), the intensity of its gravitational pull would have generated the central pressure and heat necessary to initiate nuclear reactions. And THIS would have made Saturn a star! The same applies to Jupiter, which is also a flatulant giant.
So, in other words, Saturn and Jupiter are failed stars… or that is what my astronomy professor always referred to them as.
Saturn’s rings are composed of orbiting particles of rocks and ice, some no bigger than snowballs and others the size of a bus, according to NASA’s fun cosmology website. Each of these particles, gargantuam and minute, are by definition moons, all in gentle orbit around the giant planet. They share this orbit with 63 other more “traditional” moons, the largest of which is the aptly-named Titan.
While it is unclear as to why all of this orbiting debris has accumulated into almost perfect geometric circles around the planet, the answer is suspected to lie in gravity. Over the many millions of years subsequent to the formation of the solar system (or seven days subsequent to creation), each particulate, snowball, moon and hunk of rock has had the time to settle into a position that reflects, in part, the force of attraction between itself and its giant parent planet. One might suspect that the larger, heavier particles will be arranged in belts closest to the planet, while the lighter and less dense particles will be in belts further away.
And you might suspect this because the force of attraction between two objects is proportionate to their respective masses and disproportionate to the distance between them. In other words, the heavier you are, the more attractive Earth finds you, which is why your bathroom scale groans every morning. You can refer to this spectacular blog entry for elucidation on this point: Gravity And The Laws of Attraction, Somewhat Revised.
This is precisely what I thought, but the picture is more complex than that. Each particle in orbit around its central giant – each particle of dust and each bus-sized space rock – is travelling at a certain speed. And while gravity acts to pull these particles in towards Saturn, they continue along a path that is perpendicular to it, rather than careening inwards. The force that propels these “moons” forward is called the centripetal force and you would have experienced that as a child when you were flung off a merry-go-round, because your douchebag brother seemed to think the word “stop!” meant “faster!”
Saturn’s rings are therefore organised into belts of particles that are travelling at different velocities. I have a very helpful reader to thank for this relevation and you will find his comment below.
And so, this gasy giant finds itself swathed in many beautiful, carefully arranged rings all consisting of particles, rocks, snowballs and moons travelling at varying velocities; trapped in an eternal dance around itself. Here’s something else: so does Jupiter and Neptune! The only difference is that the two latter planets’ bridal trains are thinner and far more translucent and so Saturn, with its ostentatious display, has become the planet in our solar system famed for its rings.