Celestia Forums

some guy i'm talking with on another forum believes that without the moon, the earth with spin wildly out of control and quakes and volcanoes will cease to exist.

Anyhoo, does anyone have links to credible sources disproving this claim?

Besides wikipedia. Not everyone likes it.

Neither Mars nor Venus are "spinning out of control". Neither of them has a massive moon.

I don't know about the quakes and volcanoes part, but I have read that the moon does have an effect on the Earth's rotation. Specifically that it limits changes to the axial tilt. I've read that without it, it would not be stable at 23%. I can't say specifically where I read that, just that I have.

The Earth's rotation is not stable at 23?°. It varies periodically between 21.5?° and 24.5?°.

Without the moon, the range of variation would be greater than 3?°. How much more, I don't know but I understand that 0?° to 80?° over millions of years may be possible.

I don't know how earthquakes and volcanoes would fit in, but I suspect that these are more driven by the internal heat of the Earth and not by the presence of the moon. The moon does cause tides in the solid earth and this would inject some heat. But it is unlikely that the moon is the main source of heat inside the Earth.

The Earth acts like a gyroscope in its orbit around the sun in that it maintains the direction of its spin axis in space. The implication of the conservation of angular momentum is that the angular momentum of the rotor maintains not only its magnitude, but also its direction in space in the absence of external torque. Thus the axis and the northern hemisphere will be tipped toward the sun for part of the year (summer) and away from it at another time of year (winter). This is the cause of the seasons of the Earth.
Earth Sciences
Astrology

safertr wrote:The Earth acts like a gyroscope in its orbit around the sun in that it maintains the direction of its spin axis in space. The implication of the conservation of angular momentum is that the angular momentum of the rotor maintains not only its magnitude, but also its direction in space in the absence of external torque. Thus the axis and the northern hemisphere will be tipped toward the sun for part of the year (summer) and away from it at another time of year (winter). This is the cause of the seasons of the Earth.

Copying literally from non-cited sources
http://hyperphysics.phy-astr.gsu.edu/hbase/earg.html
is bad style in "Physics and Astronomy"!

safertr wrote:Astrology

Physics and Astronomy??

Bye Fridger

It appears there is quite a bit more involved than just the moon.

International Earth Rotation and Reference Systems Service

*edit*
And, to steal a quote from the site -
"The variability of the earth-rotation vector relative to the body of the planet or in inertial space is caused by the gravitational torque exerted by the Moon, Sun and planets, displacements of matter in different parts of the planet and other excitation mechanisms. The observed oscillations can be interpreted in terms of mantle elasticity, earth flattening, structure and properties of the core-mantle boundary, rheology of the core, underground water, oceanic variability, and atmospheric variability on time scales of weather or climate. The understanding of the coupling between the various layers of our planet is also a key aspect of this research."