content long 21-August-2019 11:09:54

Winners - United Kingdom

10 - 12 years old - Movie of Saturn's moon, Tethys, passing behind Rhea


Rebecca Ngoka

I believe that the best of the three options would be a short movie of Saturn’s moon, Tethys, passing behind Rhea. Here is why I chose this option:
If Cassini makes a short movie of Tethys then we will be able to see in detail Saturn’s moon passing behind Rhea. This will benefit us because we will be able to see what things are like on different planets. A distant image of Jupiter would be unnecessary because we already have some of those and if it’s distant then we won’t be able to see much detail.
Furthermore, Cassini can capture the structure and features of both Tethys and Rhea; such as whether there are any craters or an atmosphere.
The film will show the exact movements of the two moons. Pictures don’t show as much detail. For example, a picture may be taken of Tethys passing behind Rhea. It will only show what this and the moons look like in one position; it could look completely different when in another position.
Another way that this will benefit us is that the set of grouped-together images will show something very special called an ‘occultation.’
Occultations happen when one object, like a planet or a moon, passes in front of another, hiding it from view. In this case, Rhea will pass in front of Tethys. Occultations like this give us a very accurate way to assess the orbits of these moons, which change slowly over time.    
In addition, Rhea and Tethys are still a mystery to us. Scientists are still unsure of what the interior of Tethys looks like. Some measurements suggest it has a rocky core, whereas other data indicates that it is the same throughout. Tethys is just as intriguing. It is composed of water-ice, making it one of the whitest and brightest objects in the Solar System.
Also, some reddish streaks, named “tiger scratches” have been sighted; they don’t match with any surface features. Their origin is currently unknown, which is why the third option will be of aid to our space knowledge.
Rhea was initially discovered by Giovanni Domenico Cassini. He was born on June 8th 1625 in Perinaldo, Italy and discovered Rhea in 1672. Tethys was found by the same man in 1684. Cassini named the four moons he discovered, the Sidera Lodoicea. The English translation of this is the Stars of Louis, after King Louis IV. Rhea was referred to numerically as Saturn V based on its distance from the planet. Tethys’ numerical reference was Saturn III.
To conclude, I hope my research has been of use to the investigation. I feel that the best option is definitely the third one and I am sure many others will agree with this decision.

Last Update: 20 May 2016

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