What does the word “Ring” conjure up in your head? Maybe you think wedding ring, boxing ring, Ring Ring, the ABBA song, or perhaps even battered onion rings…. Mmmm that has got me feeling hungry! For me it has connotations with a planet that is visible in the night sky in June 2013, and that planet is Saturn.
Saturn is the sixth planet from the Sun and is the second largest in the solar system. A day on Saturn is 10 hours 39 minutes long, and it takes 29.5 Earth years to revolve about the Sun. The atmosphere is primarily composed of hydrogen with small amounts of helium and methane. At the last count it had 62 Moons, but it is another feature of this gas planet which makes it spectacular, its ring system.
Although the other gas giants in the solar system, Jupiter, Uranus and Neptune, also have rings, those of Saturn are without a doubt the most extraordinary. They are by far the biggest and brightest and can be seen from Earth with even the smallest of telescopes. They are distinct and without doubt make Saturn one of the most beautiful objects in the Solar System.
The astronomer Galileo in 1610 was the first person to see the rings although he could not determine what they were with his small telescope. He incorrectly guessed that there were two large moons on either side of Saturn. It wasn’t until 1655 when Christiaan Huygens pointed his scope to the night sky that the word “Disk” was used, although he surmised that they were solid. In 1859, James Clerk Maxwell demonstrated that the rings could not be solid or they would become unstable and break apart. He proposed that the rings were composed of numerous small particles orbiting Saturn independently.
Maxwell was correct as we now know that the rings of Saturn are made from particles of rock and ice. Some of the particles can be as small as a grain of sand and some can be as big of a house. We are still learning about the rings ever since the first spacecraft called Pioneer 11 flew by in the late 1970’s called Pioneer 11. There were also close fly-bys by the Voyager 1 and 2 crafts in the early 1980’s before a dedicated probe was sent up called Cassini in the early noughties. Cassini arrived at its destination orbiting the ringed planet in July 2004. This was the first craft to orbit the giant gas planet and it still in operation as of June 2013. It has taken many images and video of this beautiful jewel in the Solar System.
There are a few theories about how the rings came to be. Édouard Roche, a French astronomer and mathematician, proposed in the 19th Century that the rings were once a moon of Saturn’s which was broken apart by the planet’s gravitational forces. Other theorists have jumped on Roche’s theory but lay the disintegration of the moon to an impact from a large comet or asteroid. A second theory puts forward the claim that the rings are actually formed from left-over material from which Saturn was formed. Either way, it cannot be denied that the rings are truly amazing and spectacular.
There are seven rings which have been labelled with an individual letter A-G. They are in the order in which they were discovered, not in alphabetical order. Starting from the planet the rings order is D, C, B, A, F, G and E. The brightest rings are A and B with ring B known for being the widest and thickest. C is quite transparent with D barely visible. The ring F is actually held together by two of Saturn’s Moons, Pandora and Prometheus (you may have heard these names before, with Pandora the fictional moon in the Alpha Centauri system on which the film Avatar is based, and there was a movie called “Prometheus” released in 2012, although being set somewhere near Zeta Reticuli, it had nothing to do with Saturn’s moon). These moons control he movement of the particles of rock and ice in this ring and are thus known as shepherding moons. The rings G and E are the furthest rings from the planet and contain almost microscopic particles.
So, earlier I did say that Saturn is visible in the 2013 June night sky. Here is how to find it. Although not fully dark, Saturn will come out around 10:30pm and will be in the general direction of South. It will look like a bright “yellow” coloured star. Close to the planet will be the bright star Spica in the constellation of Virgo. So look for two bight object close to one another. Stars will twinkle, planets do not that that is a top tip for telling them apart.
So get out and do some stargazing, if you don’t have a telescope give your friend a “ring” to see some amazing rings in the night sky!
(Article by Sinead McNicholl, Education Support Officer)