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Asked by 101owen101 to Jonathan, Samantha, Sam on 5 Jul 2012.
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Jonathan Kay answered on 5 Jul 2012:
The Moon is quite close to the Earth and smaller. It stays at about the same distance from the Earth because the forces balance out. The Earth attracts the Moon and the Moon attracts the Earth through the force of gravity. The first person to understand why that doesn’t result in them getting closer to each other was Isaac Newton, a great British scientist.
Every object with mass attracts every object with mass anywhere in the universe. Yesterday there was an announcement that scientists might have identified the Higgs boson. When that research has gone a bit further we might understand why anything has any mass at all.
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Samantha Weaver answered on 5 Jul 2012:
No – like Jonathan said gravity holds everything in orbit. The moon spins around the Earth a bit like a ball on a piece of string. Likewise, the planets revolve around the Sun. If somehow gravity disappeared the moon or planet would fly off into space rather than falling to Earth. Try it by spinning a ball around your head on a piece of string and then letting go. It won’t land on your head!
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Sam Chilka answered on 5 Jul 2012:
When satellites travel around the earth they are always being slowed down by friction with the earth’s atmosphere, so they need a fuel supply to keep their speed up. When the fuel runs out, they will keep slowing down, and will start to fall towards the earth – this is called orbital decay.
If the moon were to slow down, then it would eventually fall towards the earth. But, there is no evidence that the moon is slowing down, as there is nothing around it to make friction to slow it down.
The other planets in our solar system circle around the sun, not the earth, so there is no danger of them falling to the earth!
Comments
101owen101 commented on :
thank you 🙂