Year: 2015-16

School: Delhi Public School

Grade: 9

City: Doha - Qatar


Target: Rings and Moons

"One of the greatest fascinations of the solar system is the rings of Saturn. They have often earned Saturn the title of the most attractive planet in the solar system. The rings are located in the plane of Saturn's equator, which are inclined at 27 degrees to the orbital plane.

The rings of Saturn were thought to be the remnants of a moon that strayed too close to the planet and was torn apart by tidal forces. The boundary at which it becomes too close for a moon to orbit a planet is called Roche Limit and was calculated by Edward Roche in 1849. In 19th century James Maxwell suggested that Saturn's rings comprised many small particles rather than being single solid blocks of rings. This theory was proved by the evidence of differential rotation; the particles nearest the planet were orbiting at a faster rate than those farther out.

In 2005, Cassini space probe discovered that Saturn's rings have their own atmosphere comprising molecular oxygen. The rings are labelled alphabetically from A to G in the order in which they were discovered, rather than the order in which they orbit the planet. The rings vary in size from the E ring, the furthermost from the planet, which is 300,000 km in width to the D ring, closest to the planet, which is just 8500 km in width. All rings are relatively thin mostly less than 1 km in thickness and sit in the planet in the equatorial plane. The B ring is the brightest. The C ring lies in the B ring. The A ring contains a large number of ringlets and gaps. F is very fine and consists primarily of dust. G ring was found recently and is very narrow.

TETHYS,MIMAS AND ENCELADUS

Tethys, Mimas and Enceladus are 3 of the 6 medium sized moons of Saturn. Tethys was discovered by Cassini between 1671 and 1684.Tethys has a density similar to water, indicating it comprises mainly water ice. Most notably an immense crater named Odysseus on Tethys' surface is as of the same size of Mimas (400 km in diameter).

William Herschel discovered Mimas and Enceladus in 1789.They are the innermost of the medium sized moons. In 2005 Cassini probe discovered that Enceladus was the source of microscopic material in Saturn's outermost diffuse E - ring. Mimas, the closest of the 3 moons actually lies in the E ring, a heavily cratered moon. Cassini in 2005 found atmosphere in Enceladus mainly comprising of water vapour and a hotspot was found at the South Pole. The temperature around the pole was warmer than the surrounding planet, indicating an internal heat source on the moon, oddly focused around the pole. This phenomenon could signify another place where scientists might search for sub surface liquid water in the solar system.

CONCLUSION

It is because of these reasons I find this topic more interesting as there are more mysteries to solve in the rings and also in its 3 moons."

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