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Hi Popeye,
There are many examples of synchronous rotation within our Solar System with the example of our Moon the nearest.
A picture is worth a thousand words and I have a demonstration that I often use with school groups that graphically demonstrates synchronous rotation of our Moon.
I normally ask for two volunteers and make one student the Earth and the other the Moon. This is done indoors, I have my Earth in the middle of the room with my Moon a suitable distance from it.
I ask the rest of the group to note what wall my Moon is facing, then I have my Moon prescribe one quarter of an orbit around the Earth, but always facing the Earth. After one quarter of an orbit, although my Moon is still facing the Earth, it is now facing a different wall of the room, as in completing one quarter of an orbit it has also completed one quarter of a rotation on it's axis.
I then have my Moon do another quarter of its orbit, all the time still facing the Earth. Now, after half of one orbit of the Earth, my Moon is facing the wall in the room that initially was behind it at the start of the orbit. My Moon, in traveling half way round one orbit of the Earth has completed half of one rotation on it's axis.
I then have my Moon complete another quarter of one orbit around the Earth, effectively three quarters of one orbit, my Moon is now facing yet another different wall of the room and has rotated three quarters of one rotation on its axis.
I then have my Moon complete it's orbit. It has been facing the Earth for the entire orbit but has faced all four walls of the room in doing so. Therefore my Moon has rotated ounce on it's axis in preciously the same period that it took to complete one orbit of the Earth.
This is synchronous rotation.
The ultimate example of total synchronous rotation, involves Pluto and it's largest Moon Charon. This is the only example of total synchronous rotation within our Solar System. The time that it takes Charon to rotate ounce on it's axis is the same time that Charon takes to complete one orbit of Pluto which is the same time it takes Pluto to complete one rotation in it's axis. Therefore if you were on the surface of Pluto and could see Charon, Charon would always be in the same position in the sky. If on the other hand, you were on the surface of Pluto, opposite from Charon, then you would never know that Charon existed, Charon would never appear in your local sky.
Hope this helps.
Regards
Trevor
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