reply to post by cushycrux
That is the exct same video I have already posted once, upthread.
Stewie appeared to be under the (hopefully false) impression that you thought the Moon's rotation was caused
by gravitational attraction
When, in fact, BOTH bodies have been rotating ever since they formed. The initial states of matter, as they gravitated into spheres, and their
diameters decreased (but over-all mass stayed about the same) sped up their rotational speeds, over those millions of years. Eventually, settling
into an orbital relationship with each other that is VERY DIFFERENT than we see today.
So, the conservation of angular momentum
was at work in the formation of the spheres, but has ALSO been at work ever since. The Moon's
orbit is not perfect, and has been "spiralling" outward, ever "higher" for billions of years. Four billion years ago, the Earth/Moon distance was
much smaller, and BOTH of them rotated much faster.
The Moon's gravitational pull has "tugged" at the Earth for all that time, and this has SLOWED the Earth's speed of rotation to what it is today.
[edit=Same reason the Moon's rotation slowed, too. Earth is the 800-pound gorilla, more massive. So, Earth won that battle.]
Same time, that ENERGY is "robbed" by the Moon, and is imparted into increasing its orbital velocity. Thus, as orbital velocity increased, the orbit
HAD to change, and get farther out. That's how the physics of orbital mechanics work.
That is slightly over-simplified, for clarity. Because it is a complex interaction, and not stable over time....variable. But, there are math
calculations (from "rocket scientists") who can decipher the current orbital relationship, noting the Moon's exact rate at which it is getting farther
away, and then "work the problem backwards" to infer conditions in the distant past. It's math, and physics. Some "unknown" possible variables could
be perturbations from very large asteroid or meteor impacts, or even (unlikely, but still...) a possible ancient near-miss with some large celestial
body of some sort....not enough to seriously disrupt the orbits of most Solar System objects, but minor changes? Hard to know, without a baseline to
No astronomers to make measurements four billion years ago, and keep records for the entire time period since!
edit on 27 October 2010 by weedwhacker because: Note