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Author Topic: Why doesn't Jupiter crash it's moons?  (Read 1469 times)

Offline gazza711

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Why doesn't Jupiter crash it's moons?
« on: 13/05/2015 23:02:05 »
Why doesn't Jupiter cause it's moons to crash into it?


 

Offline Colin2B

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Re: Why doesn't Jupiter crash it's moons?
« Reply #1 on: 13/05/2015 23:12:48 »
Why doesn't Jupiter cause it's moons to crash into it?
Because the moons are moving, not stationary.
 

Offline chiralSPO

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Re: Why doesn't Jupiter crash it's moons?
« Reply #2 on: 13/05/2015 23:21:33 »
The moons are in free fall, but they are falling in a very special way that we call "orbiting." These moons have very stable orbits, meaning they will stay as they are for a very long time (but not necessarily forever--our own moon is on course to crash into the Earth in several billion years, and one of the Martian moons may crash in less than one billion!) Jupiter may have started out with many moons that it no longer has, and they either crashed into Juptier, or got flung off into space because their orbits got disturbed.
 

Offline David Cooper

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Re: Why doesn't Jupiter crash it's moons?
« Reply #3 on: 14/05/2015 18:22:17 »
You could equally ask why the Sun doesn't crash its planets. If you write a computer program to apply the inverse square law to a small object and a much more massive one, you can set it going at different speeds and see what happens. If it is stationary it will fall straight onto the other object and collide with it, but a little bit of movement sideways is all it takes to put it into a stable orbit which may be eliptical or circular. If you introduce more objects and do the same with them, you can end up with them all going round in stable orbits, but if you write more complex code to allow the gravity from these objects to pull at each other as well (I've never got round to trying this bit out), then they'll begin to interact with each other and you might find that some are driven into the central massive object or are flung off into space. The ones that survive may end up in orbits that resonate with each other, as you can see with Jupiter's moons - the outer three of the big four have resonant orbits, orbiting in multiples of the same length of time.
 

Offline Colin2B

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Re: Why doesn't Jupiter crash it's moons?
« Reply #4 on: 14/05/2015 18:44:31 »

atoms are 3d, compare atom with solar system is not correct.


Why are you putting this here? It wasn't a question about atoms. They have a right to move posts which are in the wrong topic.
This one is only about planetary orbits.
 

Offline roger_b

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Re: Why doesn't Jupiter crash it's moons?
« Reply #5 on: 17/05/2015 09:50:48 »
The moons are in free fall, but they are falling in a very special way that we call "orbiting." These moons have very stable orbits, meaning they will stay as they are for a very long time (but not necessarily forever--our own moon is on course to crash into the Earth in several billion years, and one of the Martian moons may crash in less than one billion!) Jupiter may have started out with many moons that it no longer has, and they either crashed into Juptier, or got flung off into space because their orbits got disturbed.
Do you mean that the moon orbit is constantly slightly changing and the moon is moving closer and closer to Earth?
 

Offline chiralSPO

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Re: Why doesn't Jupiter crash it's moons?
« Reply #6 on: 17/05/2015 14:33:36 »
Our moon is actually currently getting farther and farther from the Earth (very slowly), but will eventually (in a few billion years) start getting closer. http://www.thenakedscientists.com/forum/index.php?topic=51541.msg436293#msg436293

« Last Edit: 17/05/2015 14:36:29 by chiralSPO »
 

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Re: Why doesn't Jupiter crash it's moons?
« Reply #6 on: 17/05/2015 14:33:36 »

 

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