Monday, 6 September 2010
The amazing rings of Saturn are an incredibly intricate and detailed structure surrounding the gas giant planet.
The main rings reach from 7,000 km to 80,000 km above Saturn's equator, and have an estimated thickness of only 10 metres.
The rings are divided up into 7 major sections, named alphabetically in the order they were first discovered. Traveling from the innermost ring to the outermost the names are D, C, B, A, F, G and E.
The Keeler Gap lies between the A and F rings and the gap between the A and B rings is called the Cassini Division named after Giovanni Cassini who discovered the gap in 1676.
The F and G rings are very thin and difficult to see.
As you get closer, you see the rings are further divided into thousands of smaller rings.
Getting closer still, you can see the rocks that makeup the rings. These rocks range from 1 centimetre to 10 metres across. We believe they are nearly pure water ice, which reflects the sunlight very well, making the rings so bright and clear to the eye.
The Cassini space probe found that the rings of Saturn have their own atmosphere, composed of oxygen and hydrogen, produced when light from the Sun interacts with ice in the rings. The atmosphere is incredibly thin. So thin that if it were somehow condensed flat onto the rings, it would be about one atom thick.
The intricate ring structure is thought to arise, in several different ways, from the gravitational pulls of Saturn's many moons.
The passage of tiny moonlets such as Pan clear out some of the gaps, while other ringlets seem to be held in place by the gravitational effects of other small moons we call shepherd satellites.
Scientists think the moon Mimas holds the Cassini Division in place.
There are two main theories regarding the origin of Saturn's rings.
One proposes that the rings were once a moon of Saturn 300 km in diameter, bigger than Mimas. Either its orbit decayed until it came close enough to be ripped apart by Saturns gravitational field or it was struck by a comet breaking it apart.
The last time there were collisions large enough to break up a moon that big was during what is known as the Late Heavy Bombardment four billion years ago.
The second theory suggests that the rings were never part of a moon, but are instead left over from the original material from which Saturn formed.
In either case Saturn's rings seem to be very old. They are one of the most distinctive and beautiful features of our solar system.