Sun-Earth-Moon Gravity

Aside from cavediver's answer, my personal opinion is that our current understanding of how the forces of nature work is still vastly incomplete. Therefore, any attempt at answering a question that deals with the universe as a whole should be taken with at least a hint of skepticism. After all, the classical physicists thought they had it all figured out until something like the ultra-violet catastrophe came along.

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To answer the original question (which hasn't quite been done yet), is that the sun is not pulling the earth, or the moon, in "towards" itself in the way you are thinking. In circular motion, an object tries to move tangentially to a second object. But force of attraction caused to motion to not be purely tangential, which would cause the first object to continue to move to infinity, but rather to be angled slightly towards the second object. This happens at each moment in the motion, giving rise to a circular orbit, rather than the naturally linear one.The key thing to observe in circular forces is the resultant velocity. The sun's force on Mars is greater than its force on Earth, but this only causes Mars to circle to sun faster and at a smaller radius. Circular forces do not pull object towards the center of the orbit, they only change the way in which the objects circle around the center.So it wrong to ask why the sun does not pull the moon away from the earth, because the sun's force is only making the moon rotate around the sun, not to be drawn towards it.

Platypus writes: Think someone made a mistake.

I was gonna point this out like 20 minutes ago but reconsidered because I don't like being nitpicked on and certaintly wouldn't want to nitpick other people. But now that someone's done it for me, might as well get the rest out of my system. A few minor nitpics Should be "angular", not circular.There is no such thing as a "linear orbit".No such thing as a circular or "angular" force (at least not how you are defining it). All gravitational forces pull other objects toward the centers of the sources of the forces. The word "orbit" should be used here.

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Really? Oh thank God. You may just have saved the tens of thousands of professional cosmologists/particle physicists/relativists from wasting their lives on a useless pursuit. Have you written to all of the relevant departments yet? They will be overjoyed to hear from you! You're so right. All my time as a professional scientist was spent unwittingly making this very same error, but now you put it this way it is so easy for me to see the complete folly behind my approach.

Somehow, you translated "my personal opinion is that our current understanding of how the forces of nature work is still vastly incomplete" into "my personal opinion is that we shouldn't even try to understand the forces of nature..."What's wrong with having some reservations? There was no error behind the catastrophe. The classical model was just inadequate to explain the observation at the time and so eventually another model came along (QM) that could explain it. Again, the cautious me says that we're bound to run into problems later on that may need to move onto a new model.Don't get me wrong, I'm not saying at all what you thought I was saying. Remember that I was talking to someone who obviously did not have even the basics down. The typical questions that we usually get from someone like that usually reveal that they expect science to take the same approach to the questions as religious doctrines. I just wanted to make sure that he knows science isn't about "this is the truth and all others are false..."Anyway, have you had a couple of drinks?

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Ok, first off has little to no relevance in science.You then follow your "personal opinion" with That's a mighty big conclusion to draw from your own personal opinion. It may well be true, but it hardly follows... The error was in Believe me, none of us think like that (although a couple did back around 1980 with N=8 SUGRA, but they shall remain nameless) Of course there are problems. And of course there will be modifications and new models. But to direct the level of tentativity you did at the most basic elements of GR is naive. If I had been explaining the ways in which string theory can remove the singluarities of GR, or even how cold dark matter factors into the large scale structure of the universe, you would have a point. But we are talking about the most accurately tested theory known to man, a theory that is over 90 years old. It will require a bit more than anyone's "personal opinion" to budge. Not at all. I'm just very defensive about my life's passion. Just remember, what I described is not some new-fangled hyper-theoretical super-jargon - it is exactly as it would have been explained in 1915... except they wouldn't have had the luxury of ninety years of solid evidence to back them up!

There's a reason why I said "my personal opinion". It means take it or leave it and it means absolutely zip if trying to apply it to real science. It was just the skeptic in me talking. Point taken. Well, I'd understand your defensiveness if I proclaimed my words to be the truth of all truths in science. Again, there's a reason why I said "my personal opinion". I was just trying let him know that scientific models aren't treated as doctrines and that healthy skepticism is encouraged.Again, I have run across too many people that think scientific theories and models are equivilent to doctrines in religion. The last thing I want is for them to get an impression that the answers we give is equivalent to the 10 commandments.

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Sun cannot pull away Moon from Earth because of the following condition:The difference of gravitational accelerations caused by Sun on Moon to that caused by Sun on Earth is less than gravitation acceleration caused on Moon by Earth.I.e.,Acclelration due to gravity of Sun on Moon - Acceleration due to gravity of Sun on Earth < Accleration due to gravity of Earth on MoonThat is why Moon still orbits Earth without settling in an independent orbit of its own like that of Mars.In other words while orbiting around Sun, both Earth and Moon are accelerating towards Sun without much difference in their individual accelerations.When we are talking about differences in gravitation acceleration over distances, we are basically talking about tidal forces.

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Usually, in a well-conducted debate, speakers are either emotionally uncommitted or can preserve sufficient detachment to maintain a coolly academic approach.-- Encyclopedia Brittanica, on debate

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Um, no. That's not the reason why the moon is orbiting the earth. In fact, that's not even true. The gravitational force between the moon and sun is stronger than gravitational force between earth and moon. Actually, that's not the reason why the moon doesn't appear to have its own independent orbit. If mars is close to earth, the two planets would be orbiting each other.But if you look at the path of the moon around the sun and completely ignore that the earth is there, you'd see that the moon does indeed orbit around the sun.So, the question "why doesn't the moon orbit the sun?" makes no sense. Why? Because the moon does orbit the sun.

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We are BOG. Resistance is voltage over current.

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Disclaimer:

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Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

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He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

Tazmanian Devil, you need to think more on what I wrote. This is not something which just came out of my mind but is the exact scientific explanation.Yes, Moon does orbit the Sun, but that is not my point, it doesn't have an independent orbit like that of an asteroid or a planet. In fact it is part of gravitationally bound Earth + Moon system which together orbit the Sun. So there is a difference in having an independent orbit or orbiting by being part of a gravitationally bound system.If a gravitationally bound system like Earth and Moon have to separate by a force external to this system (like Sun's gravitational force), it is not the intensity of Sun's force on any particular body - Moon or Earth that counts. So even if Sun pull's Moon twice as stronger than that of Earth on Moon, still the Moon does not need to separate from Earth.It will separate only if the tidal forces of Sun on Earth-Moon system trying to pull away Moon from Earth are stronger than the gravitational force of Earth on Moon. In other words both Earth and Moon are accelerating towards the Sun, it is the difference in the acceleration, i.e., the net acceleration of separation of Moon from Earth due to Sun (in other words tidal force) that counts. This should be greater than the acceleration due to gravity that binds Moon to the Earth.Tidal force of Sun separating Moon from Earth = Mass of Moon * ( accln due to gravity of Sun on Moon - accln due to gravity of Sun on Earth). This tidal force should be greater than the gravitational force that binds the Earth and Moon system.Edited by 2gud, : No reason given.Edited by 2gud, : Re-phrased certain sentences

Point taken.Well, I guess sometimes the bleedingly obvious needs to be pointed out.Anyway, I'm still right and you're still wrong

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We are BOG. Resistance is voltage over current.

​

Disclaimer:

​

Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

Please let me know where you are right and where I am wrong.I don't have a problem in accepting if I am wrong I thought none of us are Prophets (messengers of God whose words are infallible) and we are discussing a scientific topic!

Um, the smilie with the tongue sticking out usually means it's a joke.But to be fair, your answer doesn't really address the question in the original post. Originally, the question is "why doesn't the moon orbit the sun?" Well, the answer is "you moron, the moon does orbit the sun."

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We are BOG. Resistance is voltage over current.

​

Disclaimer:

​

Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!