# Earth's Orbit & Fleming's Left Hand Rule

1. Jul 21, 2015

### EtherURWithMe

Please forgive me as I am inquisitive enough to be dangerous.

Question First, Thoughts Behind It:

* How much validity is there in the application of Fleming's Left [edit: RIGHT!] Hand Rule towards the orbit of the Earth around the Sun? *

I saw that NASA recognizes this but they seem to sort of shrug and say "meh".
http://science.nasa.gov/science-news/science-at-nasa/2006/30nov_highorbit

I can't help but notice that the earth's orbit appears to follow (as best i can tell) all the specific parts of Fleming's Left Hand Rule.

Given that the planets and the sun are giant balls of metal moving through a medium with permittivity, is it not a valid assumption that the sun would put off a magnetic field at a right angle to it's motion of travel?

In the laboratory when one is examining this phenomenon it is often suggested to hold a compass up around this field to observe the direction in which the needle points.

How much resemblance does the "pointing" of the earth's axis have with this?

Earth's orbit:

One final question.
Much is made of the "fact" that gravity only attracts, while the electrical and magnetic forces can also repel.

But what would happen if we could flip the earth's poles?
Is it not conceivable that there would then be a repulsion?

Last edited by a moderator: Jul 21, 2015
2. Jul 21, 2015

### EtherURWithMe

I think I meant "RIGHT HAND RULE". Sorry. It's been a couple days since I was digging in to this.
If the earth is orbiting clockwise, it should be the Right Hand Rule.

Which would make the assumption then that the Sun is a charged particle, and the field emitted to be a magnetic field.

[as opposed to my "incorrect" LHR which would make the Sun a magnetic particle emitting an electric field, and put the earth orbiting backwards?]

3. Jul 21, 2015

### Bandersnatch

Consider:
- Earth is not a charged particle; all objects in the solar system are electrically neutral; try putting some numbers on this to see how charged Earth would have to be to stay in orbit due to the solar magnetic field;
- solar magnetic field flips its poles every 11 years. Latest flip was in 2013-14 iirc. I'm pretty sure the Earth and the rest of the planets haven't reversed their orbits;
- gravity explains orbital mechanics perfectly, to the best of our measuring abilities; there's no room for another force to be at play.

4. Jul 21, 2015

### Staff: Mentor

None. The right hand rule is for magnetism. The Earth and the other planets orbit the Sun because of gravity. The Sun's magnetic field is negligible at planetary distances.

This link gives a "page not found". Anyway, I would be extremely surprised if NASA thinks magnetism is a significant effect on the Earth's orbit; NASA has looked into some crazy things, but not that crazy.

The Earth has a metallic core, yes, but the Sun doesn't; it's a big ball of plasma with negligible metallic content (the vast majority of the Sun is hydrogen and helium). We're not sure how much metallic content most of the other planets have. Anyway, that's irrelevant since, as noted above, the Sun's magnetic field is negligible at the distances the planets are from the Sun.

None. The Earth is not a compass, and the direction of its axis is not determined by an external magnetic field or anything like it.

No. There are positive and negative charges, but only one kind of mass/energy. Changing the direction of rotation of an object doesn't change the sign of its mass or energy.

5. Jul 21, 2015

### Staff: Mentor

In addition to the posts above: special relativity tells us there is no such thing as absolute motion. "The direction of the motion of sun" is a meaningless concept, only relative motion is interesting.
Even if you choose a coordinate system where the sun is moving, and even if the sun and earth would be charged, then the earth is still moving in the same direction, making the net magnetic effect zero.

=> does not work in literally every aspect.

6. Jul 21, 2015

### Bandersnatch

Apparently, the link was poorly formatted. Here's the correct one:
http://science.nasa.gov/science-news/science-at-nasa/2006/30nov_highorbit/

@EtherURWithMe They're talking about the right hand rule in the context of finding the direction of angular momentum. This has got nothing to do with electricity or magnetism being at play in orbital mechanics, but everything to do with finding the direction of a vector cross product.

7. Jul 27, 2015

### Ken G

Another point to bear in mind is that we already measure the Earth's magnetic field, and the magnetic field in the interplanetary space through which the Earth moves. So we don't need to speculate about these effects, we can calculate them, and see that they are negligible for things like the Earth's rotation and orbit. Gravity is the only force strong enough to affect those things.