Thread: This may seem like a dumb question...

1. Why do planets rotate? I understand why they revolve, but I don't see what makes them rotate. Am I missing something obvious?

And can someone explain synchronious orbits to me?

aaand one more thing-I read this on http://physics.fortlewis.edu/Astrono...ML/AT30803.HTM
As just mentioned, the Moon's rotation period is precisely equal to its period of revolution about Earth—27.3 days so—the Moon keeps the same side facing Earth at all times

How does this work. If it's rotating then the same side can't be facing earth because it's spinning...or that's what I thought. What am I missing?
Even the diagram on the website shows a different side of the moon facing the Earth at different times.

2.

3. they rotate because the discs they were created from rotated and that momentum is still here as rotational m,omentum on the planbets.
syncronised orbit is simply a orbit that have the same time to complete one orbit the planet have to make one day

4. Or to put it another way: When a satelite is in synchronous orbit it will pass directly over a given spot twice a day, a geosynchronous orbit however always remains over a given point aslong as that point is on the equator. These are both orbits at the same distance from earth(or what ever body ), any other orbits(usually lower orbits) may take weeks months or years to pass directly over a given spot twice.

5. But how can the same side always be facing the planet if the satellite is rotating? Do satellites rotate? I thought they did...

6. The satellite is rotating very slowly so it takes a long time to fully spin. Here's something you can try that might help you understand how this works. Find a tree and stand a couple steps away from it facing it. Now shuffle around it, staying the same distance from the tree and always facing it, until you get half way around the tree. Now you have spun yourself by half a rotation... if you were facing north at the start you are facing south now and that's what the moon and satellites do, only the Earth isn't a big tree.. :S :P hope that kinda helps..

7. I get it! That was awesome! Thanks so much.

wow...I feel like a little kid, I have to walk around a tree to understand it.

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