|LoFi version for PDAs||Help Search Members Calendar|
|Welcome Guest ( Log In | Register )||Resend Validation Email|
|Robittybob1||Posted on Today at 8:28 AM|
From the diagram, looking from the lower left hand corner, follow the arc up to the right and see how the Moon takes quarter revolutions around the Earth. So that is the way the Earth "throws the Moon up and over itself" but it is not just the Moon orbiting the Earth but the Moon is coming and going from the Sun as well and this will affect its kinetic energy to potential energy balance. So I guess it is really difficult to take the eccentricity out of the Moon-Earth system, even though with the Yo-yo Moon Capture theory when they were tidally locked, I'd like to know whether all this eccentricity was present then or not? If my reasoning is correct the eccentricity is inherent, but with the larger orbit, as the Moon is making now compared to then, I would hazard a guess that the eccentricity is getting worse because the radius is getting larger (the Earth is adding energy all the time), but on the other hand it could be lessening because the orbital period is getting longer. So which effect dominates?
Any comments on what the answer maybe please?
The study below has picked up an increase in the eccentricity of the Moon. So maybe the action of throwing the Moon into a higher orbit, which implies the Moon gets both closer to the Sun and further away depending on which side of the Earth it is on, has an intensifying effect on the Moon's eccentricity. Well that is my rough and ready guess.
The following study could be read:
"On the anomalous secular increase of the eccentricity of the orbit of the Moon"
I thought it a bit odd they didn't have an explanation for the increase in eccentricity yet I had proposed a reason even before I had known about this scientific study!
|Capracus||Posted on Today at 7:33 AM|
How does a Theia collision alter the history of life on Earth? It wold be another 800 million years before the appearance of life on Earth, still ample time for development.
|Robittybob1||Posted on Today at 3:36 AM|
I want to clear up one thing, for there seems to be a contradiction in what I have said in the last several posts:
1. "3. At each pass of the planets Earth and Luna, the relative motion between the planet Luna (Moon) is slowed by speeding the Moon up (lower Lunar -Sun orbit)
(This must mean the period between conjunctions increase with time, as the orbital periods become synchronized. This bit is a logical consequence of #3.)"
And prior to that:
2. "The Moon gains speed on one leg, the Moon and the Earth move toward each other relatively (as well as orbiting the Sun, so I'm not suggesting anything goes backwards). The Moon would then slow on the going-away half of the orbit. I think that means the two halves are dynamically balanced."
So I will agree that these two statements are partially true but also a little contradictory too, for I would say that if there was angular momentum transferred the two halves of the orbit will not be fully dynamically balanced as a consequence. The transfer of the momentum dampens the balance.
This transfer of momentum would tend to make the Earth and Lunar spin anticlockwise looking down on the system. [I will try to use the term Luna for the planet Luna prior to its capture as the Moon.]
|Robittybob1||Posted on Yesterday at 11:11 PM|
| It is one thing to say the Earth captures the planet Luna and throws it over itself! I have to really figure out if that is possible.
It must have been possible for other planets as plenty of the planets have captured moons, but is it possible for Earth to capture Luna?
I like the way the tidal deceleration has worked to synchronize the two bodies (bringing them into nearly the same orbital period).
I recall seeing a diagram (Trippy's?)of the Moon's wavy passage around the Sun. The Moon orbits the Earth but this is more or less created from periods of dropping toward the Sun and then being flung out again. The Moon never goes backwards when viewed from the Sun.
This image gives the idea correctly, whereas most YouTube animations have the scales out so much it looks like the Moon goes periodically backwards when viewed from the Sun's perspective.
|Robittybob1||Posted on Yesterday at 7:52 PM|
| So to recap some of the features of the Yo-yo capture theory in the last page:
1. There was a slow to non-spinning Earth prior to Moon capture.
2. The Earth catches up to the Moon via the natural orbital velocity difference.
3. At each pass of the planets Earth and Luna, the relative motion between the planet Luna (Moon) is slowed by speeding the Moon up (lower Lunar -Sun orbit)
(This must mean the period between conjunctions increase with time, as the orbital periods become synchronized. This bit is a logical consequence of #3.)
4. Earth Moon interact captures planet Luna (Moon) and throws it into an elliptical orbit over the top of the Earth from the Sun's perspective.
|Robittybob1||Posted on Yesterday at 5:27 AM|
| Looking to see if I can get help with the the dynamics of Moon capture.
I came across this interesting discussion on the possibility of Moon Capture.
"LUNAR ORIGIN MODELS > THE CAPTURE MODEL"
Some good points and nothing to really indicate the Yo-yo theory is incorrect. In fact they even suggested that it is possible for a moon to go from the retrograde orbit to a prograde orbit. To me that means at some stage any moon that did this must stop and probably become tidally locked at the turnaround.
The logic is you can't change linear direction without stopping at some point.
Remember the Yo-yo theory also has the Moon and the Earth becoming tidally locked together 3.5 billion years ago.
But up to now I haven't had to think about the Moon starting off with a retrograde orbit, but it is worth knowing, but I doubt whether it will help.
You know I am beginning to think there have been so many attempts to account for the Moon's origin that a theory like the Yo-yo theory may have already been proposed, but I haven't read about yet.
|Robittybob1||Posted on Yesterday at 12:41 AM|
| There is a force of gravity between the two bodies Earth & Moon (E&M). This force will cause an acceleration A = F/M (from F = M * A), from the acceleration we can find the new velocity V = A * t. The time is 10 years
V then affects the period and radius for any extra energy will be converted to gravitational potential energy so the Moon's orbit with the Sun will alter and make the Moon orbit Faster (or slower) (which) at a different height The change in height will take (mgh) 50% of the extra energy in the system (the other 50% is in the Earth dynamics (even though we are saying for simplicity sake the Earth doesn't move).
That is the bit I'm unsure of at the moment???
This means that even though the Moon slows down due to the Earth pulling it back (so to speak), but because it drops in toward the Sun, it will actually be orbiting faster and moving forward faster, this still means the time to conjunction will increase for the Earth won't be catching up to the Moon as fast. (all from the effect of slowing the Moon ends up making it go faster but on a different orbital radius.
Have I got that logic right?
|Robittybob1||Posted on May 19 2013, 10:04 PM|
If the co-planet Moon is pulled toward the Earth how much does it speed up? does the speeding up significantly change the period of conjunction? I'm thinking it must. 16058 years is time taken for the natural difference in orbital period of the Early Moon-Early Earth to allow one complete lap, if they accelerate toward each other as they approach, some of this is reversed as it leaves the Earth, so that must mean the average velocity is higher and period is reduced.
But by how much? The Moon gains speed on one leg, the Moon and the Earth move toward each other relatively (as well as orbiting the Sun, so I'm not suggesting anything goes backwards). The Moon would then slow on the going-away half of the orbit. I think that means the two halves are dynamically balanced.
With our calculations we will use both the Early Moon-Early Earth as 42 times the current masses, remember. So you might agree the Earth and Moon at opposite sides of the Sun would have only minimal gravitational affect on each other. At the conjunction the tug will be the strongest. I know this isn't rocket science.
Assuming it is a circular orbit there is a radius and the change in "theta" the angle between them.When the speed changes both theta and radius will change too.
Since the Moon is much less massive than the moon we could look at the situation assuming all the changes affect the Moon only to begin with and when we feel happy with the results we will complicate the situation by having them both move.
Earth:Moon mass ratio = 81.3:1 (Moon Earth mass ratio = 0.0123)
Theta change per year = 360/16057
so we will look at 10 year blocks. This gives 0.22420128 degrees change in theta every 10 years and we will look at this finer when the rates become significant. There is probably more movement occurring in the last year prior to conjunction than in the first 5000 years after their greatest separation. So sensitivity in the later stages will be important.
|Robittybob1||Posted on May 19 2013, 09:07 AM|
Probably a bit like a double pendulum? - Just joking. Try and predict the motion!
|Robittybob1||Posted on May 19 2013, 08:23 AM|
| If it is possible to imagine it happening like this does that mean it is possible to put maths to the problem? I can't see why NOT but it will be interesting to see it. It is a matter of being able.
Am I able to do it?
Where do you start?