The Planet Saturn
Monday, March 22. 2010

 On Monday 22 March, 2010, Saturn was at its closest to Earth and was fully illuminated. The rings, however, are approaching their edge on position and it will soon be difficult to see any details. The ring position as viewed from the Earth varies with the relative position of Saturn to the Earth and with Saturn’s orbit round the Sun. The planet is at its brightest when the rings are at the maximum inclination to its
orbital plane and at present these are moving gradually to a position where they will be edge on as viewed from the Earth. Saturn’s poles are tilted 26.4 degrees to the plane of its orbit, as are the plane of the rings. Due to this configuration, Saturn’s rings present a different and progressive picture to the Earth throughout its 29 earth-year orbit round the Sun

On 31 December 2003, Saturn was of magnitude -0.5 when its ring angle was 25.5 degrees, while on 22 March 2010 its magnitude was only 0.5 when the angle of its rings was 8.7 degrees Saturn is the second most massive planet, and the second largest in size. It is a Gas Giant, with a rotational period of 10-11 hours (depending onlatitude), and with an orbital period of 29.5 years. Its rapid rotation flattens Saturn at the poles by about 10%, making it the most oblate planet. Its composition is mostly hydrogen and helium and is largely liquid but it is likely to have a dense rocky core, probably 15 to 20 times as dense as that of the Earth’s. Saturn has an internal heat source, and radiates more energy than it receives Saturn has the lowest overall density of any planet in our solar system, of 0.7 g/cc, which is less than that of water. The interior is probably similar to Jupiter, with metallic hydrogen responsible for the strong magnetic field of Saturn. The
concentration of helium relative to hydrogen is somewhat less than that of Jupiter. This is thought to be due to the colder temperature of Saturn. The volume of Saturn is 755 times that of the Earth and 95.2 times as massive.
To date, 61 moons have been found orbiting Saturn. The largest and major ones in order of size are: Titan 5800 km. in diameter, Rhea 1450 km., Japetus 1800 km., Tethys 1200 km., Dione 1150 km., Enceladus 630 km., Mimas 485 km., Janus and Hyperion 300 km., and Phoebe 200 km.

1610 - Galileo Galilei becomes the first to observe Saturn's rings with his 20-power telescope. He thought the rings were "handles" or large moons on either side of the planet. He said "I have observed the highest planet [Saturn] to be tripled-bodied. This is to say that to my very great amazement Saturn was seen to me to be not a single star, but three together, which almost touch each other "

 1883 - The first photograph of Saturn's rings is taken by Commons.

(Information obtained by courtesy of  The Hamlyn Guide to Astronomy and graphics from the NASA website –“Historical Background of Saturn’s Rings”)

This article was submitted for Griceland Observatory by research astronomer Dave Robinson.

Main image taken on the 23rd March 2010 with a Philips Toucam and Meade 12" LX200 Classic telescope. 1000 images were taken in K3CCD and the best 300 were aligned and stacked resulting in this composite. Final processing done in Photoshop CS2....