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Do all the planets take the same time to revolve around the sun?
Question Date: 2015-03-02
Answer 1:

Hi, thanks for the cool question. Can you imagine that over 400 years ago a scientist called Johannes Kepler found a law that describes how the planets rotate around the sun? And many thousand years before that, people were already looking at the stars and observing that planets rotate around the sun. I always find that amazing. Anyway, the short answer to your question is: No!.... The further a planet is from the sun, the longer it takes for the planet to move around the sun. There are two reasons: Firstly, try to imagine walking in circles around a chair in the middle of a room. If you are very close to the chair, you will take a short time to walk around. Now if you move far away from the chair and walk at the same speed, it will take you a long time to walk a circle around the chair. This is the same for planets moving around the sun. The further away, the longer you have to go. In addition to that, planets that are farther away from the sun and have longer to go also revolve at a slower speed than the planets close to the Earth. Those two facts together cause a planet that is far from the sun to take much longer to revolve around the sun than planets close by.

Thus for example Jupiter takes nearly 12 years to go around the sun and Pluto takes 248 years. On the other hand, Mercury (the closest planet to the sun) takes only 88 days to revolve around the sun.

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