- #36
Hurkyl
Staff Emeritus
Science Advisor
Gold Member
- 14,981
- 26
Misspoke?DaveC426913 said:The Moon has a ... Earthrise, Earthset.
Misspoke?DaveC426913 said:The Moon has a ... Earthrise, Earthset.
Funny, but true. Gravitationally-locked satellites have some interesting qualities.Hurkyl said:Misspoke?
JaredJames said:The moon orbits the earth, if it didn't spin we'd see a different piece of the moon each night. Your picture supports the fact it is spinning by only showing one piece of the moon ever being shown.
DaveC426913 said:The Moon does indeed rotate about its own axis. The Moon has a sunrise, sunset, starrise starset and Earthrise, Earthset.
The fact that we here on Earth see one side facing us at all times does not mean it does not rotate, in fact, it proves it does rotate.
ttown_okie said:If the moon had any spin at all we would be able to see all sides of it, because we can not, you know that the moon is not spinning on its axis.
ttown_okie said:The moon is not rotating about its own axis at any point in its orbital path.
JaredJames said:Not true, it is spinning but timed perfectly so we only see one side.
If it wasn't spinning, the same side of the moon would always face the sun and we would see a different area each night.
Your picture supports us not you.
ttown_okie said:I do not think so, the orbit around the Earth is the reason one side faces the Earth. If the moon was spinning this would not happen. If I fly a plane in an orbit around the Earth, at no point in time did I have to apply a rotational force to my plane to correct for the curvature of the Earth, I simply flew parallel to the Earth with my engine always applying thrust perpendicular to the Earth. It is the same with the moon, the core of the moon is not imparting any spin at all to the moon itself. One side faces the Earth because of gravity. therefore the moon does not rotate abouts its own axis. I think you mean that it rotates about the Earths axis.
Timoothy said:Below is a gif that might help.
Notice that the red dot makes one complete rotation around the axis (green dot) of the moon during a complete orbit of earth.
http://h1.ripway.com/cluelusshusbund/Moon/MoonEarthOneRotation.gif
JaredJames said:What does the core have to do with anything? The core isn't the reason the Earth spins so why is the moon special?
ttown_okie said:The cores of the Earth and the moon are vastly different. The core of the Earth supports a strong electromagnetic field around the Earth, the moon does not have this. I did not say the core is the absolute reason the Earth spins, but it is an important piece of the puzzle as to why. What is your theory about why the Earth spins, I can describe mine if you like.
Borek said:ttown, think about it this way. Earth rotates - no doubt about it. Now imagine a geosynchronous satellite. It always hangs exactly over the same point on the Earth surface, so it always sees exactly the same view of the Earth - as if the Earth wasn't rotating. So, if you were living at geosynchronous satellite you would think Earth doesn't rotate, even if it does.
This is not much different from what happens to the Moon - it rotates, but from the point of view of someone living on the Earth it always shows the same side, so it looks like if didn't.
JaredJames said:I don't care for your theory, neither does science. The Earth's core has nothing to do with the reason the Earth is spinning.
ttown_okie said:Please enlighten us.
JaredJames said:http://en.wikipedia.org/wiki/Earth's_rotation
No one knows for sure, but the current theories have nothing to do with the core causing the spin.
It's not "us", it's just you.
ttown_okie said:I agree that no one knows for certain but it is quite arrogant to claim the core has nothing to do with rotation of the Earth when nobody knows. I think the magnetic field flowing through the core has something to do with the Earth rotation and if the core was comprised with an entirely different composition it would quite likely affect the rotation of the Earth.
JaredJames said:There's a difference between the spin of the Earth affecting the core and the core spinning being the cause of the Earth spinning. You claimed the latter.
ttown_okie said:At no point have I ever said that the core spinning cause the Earth to spin. In fact have have not said why I think the Earth spins in this thread at all. I did acknowledge that yes I do think the core has something to do with it. I do not think a spinning core explains it.
ttown_okie said:I did not say the core is the absolute reason the Earth spins, but it is an important piece of the puzzle as to why.
ttown_okie said:I can visualize what you are saying but the satellite is orbiting the Earth, not he other way around.