The spin of the earth .

[Roger Dynamic Motion]

Question : What are the coordinate vectors responsible for the earth; to spin?.

[KipIngram]

Just a few days ago, in response to another thread, I proved (as far as I can tell) to myself that if material that is originally spread out across a range of solar radii, with each piece originally pursuing its own independent orbit, coalesce into a planetary body then rotation is required. I did assume circular orbits, but based on something Mordred said about the virial theorem I think it could be used to extend the proof to elliptical orbits.

 

The proof also assumes that all of the original pieces are orbiting in the same direction, but I imagine it would be much less likely for counter-rotating pieces of material to coalesce given they'd have a very large velocity with respect to one another.

 

If you are interested I can post that here, or I can PM it to you.

 

The gist of it is that energy conservation restricts the final radius to a value that is too small to provide conserving angular momentum, so rotation is required to make up the difference.

If you're just asking what vector represents the planet's angular momentum, then that is a vector parallel with the axis of rotation and with direction found by the right hand rule (for Earth it would be from South Pole to North Pole.

[swansont]

Coordinates or vectors are not responsible for spin. They describe it.

 

You can use whatever coordinate system you wish, though some would be easier to use. e.g. Spherical coordinates, or some closely related system, because the earth is a spheroid.

[Mordred]

Its good your using the virial theorem and yes it does also apply to elliptoid orbits. The virial theorem naturally obeys the conservation of angular momentum.

[frankglennjacobs@gmail.com]

Maybe if any item in the protoplanetary disk were not in orbit, it would just fall straight into the sun.

 

So that leaves the items that are in orbit. ?No?

 

When two such items combine, the one with the very slightly higher orbit will be traveling just a little faster.

 

That will tend to make the combined pair rotate toward the east.

 

(No. That is not how to say it. Clockwise? No. To the right? No. Roger, help me with this terminology.)

 

When a billion such items have coalesced, is not their rotation combined?

 

Is it not in the same direction as nearly everything else?

 

It seems very odd to notice a large object in orbit -- not rotating nor revolving in the same direction as the others.

 

(Little children point and say, "!Look, Mamacita! A retrograde satellite.")

Edited May 29, 2017 by frankglennjacobs@gmail.com

[Roger Dynamic Motion]

Maybe if any item in the protoplanetary disk were not in orbit, it would just fall straight into the sun.

 

So that leaves the items that are in orbit. ?No?

 

When two such items combine, the one with the very slightly higher orbit will be traveling just a little faster.

 

That will tend to make the combined pair rotate toward the east.

 

(No. That is not how to say it. Clockwise? No. To the right? No. Roger, help me with this terminology.)

 

When a billion such items have coalesced, is not their rotation combined?

 

Is it not in the same direction as nearly everything else?

 

It seems very odd to notice a large object in orbit -- not rotating nor revolving in the same direction as the others.

 

(Little children point and say, "!Look, Mamacita! A retrograde satellite.")

your quote ../ Maybe if any item in the protoplanetary disk were not in orbit, it would just fall straight into the sun.

 

Where is the sun located in your statement ?

[frankglennjacobs@gmail.com]

The sun (or protosun) would be in the dynamic center of the rotating protoplanetary disk. Itself would be rotating in the same direction, because each item of infall would either have no angular momentum or else it would have whatever angular momentum it had until impact. This would be transferred to the sun (or protosun). (Of course, any item with some other vector of angular momentum would add its own energy to this.)

[KipIngram]

That was my first line of reasoning too, but the conservation of energy / momentum seemed more rigorous, and led not only to rotation but to rotation such that the solar day is longer than the sidereal day.

[Roger Dynamic Motion]

The sun (or protosun) would be in the dynamic center of the rotating protoplanetary disk. Itself would be rotating in the same direction, because each item of infall would either have no angular momentum or else it would have whatever angular momentum it had until impact. This would be transferred to the sun (or protosun). (Of course, any item with some other vector of angular momentum would add its own energy to this.)

protoplanetary disk,,/

 

is It a Galaxy? you have in mind.

That was my first line of reasoning too, but the conservation of energy / momentum seemed more rigorous, and led not only to rotation but to rotation such that the solar day is longer than the sidereal day.

The sun our sun that we see every day ../ where is it located ?/ Near the black hole ?

[KipIngram]

The sun our sun that we see every day ../ where is it located ?/ Near the black hole ?

 

? I don't know what brought a black hole into the thread. Our sun is well away from the center of the galaxy. Seems like I've read somewhere we're about 2/3 of the way out to what's considered "the edge"?

[Roger Dynamic Motion]

? I don't know what brought a black hole into the thread. Our sun is well away from the center of the galaxy. Seems like I've read somewhere we're about 2/3 of the way out to what's considered "the edge"?

ok than!~I have nothing to follow with if the sun is not at the center of the Galaxy.

[frankglennjacobs@gmail.com]

I can't quite put my finger on where I heard it, but the word is that the entire Galaxy is rotating or it would fall into itself.

 

The Galaxy is a loose arrangement of about a thousand-million stars. (There are thousands of millions of other galaxies, too.)Somewhere there's a connection between the rotation of the Galaxy and the rotation of the protostars and their protoplanetary disks, getting down to our own planet and so on. Maybe it works the same way for really BIG dust clouds as for the "mere" cubic parsec sizes.

 

I believe we are 25,000 light years "out' from the center of our Galaxy, but you can usually see it, edge-on, on a clear, dark night without a telescope or even binoculars.

 

The nearest star (besides, of course, the sun) is calculated to be about four light years away.

 

Look it up and see if the "Solar Day" is the time for the earth to rotate the same side to the sun, and if the "Sidereal Day" is the time for the Earth to rotate the same side to the same spot among the stars. These two "days" are slightly different because the earth is in orbit around the sun, covering approximately one degree a day of sky. (There should be enough material attached to those to flesh out your Thread on rotation.)

Edited May 30, 2017 by frankglennjacobs@gmail.com

[swansont]

I can't quite put my finger on where I heard it, but the word is that the entire Galaxy is rotating or it would fall into itself.

 

The Galaxy is a loose arrangement of about a thousand-million stars. (There are thousands of millions of other galaxies, too.)Somewhere there's a connection between the rotation of the Galaxy and the rotation of the protostars and their protoplanetary disks, getting down to our own planet and so on. Maybe it works the same way for really BIG dust clouds as for the "mere" cubic parsec sizes.

 

I believe we are 25,000 light years "out' from the center of our Galaxy, but you can usually see it, edge-on, on a clear, dark night without a telescope or even binoculars.

 

The nearest star (besides, of course, the sun) is calculated to be about four light years away.

 

Look it up and see if the "Solar Day" is the time for the earth to rotate the same side to the sun, and if the "Sidereal Day" is the time for the Earth to rotate the same side to the same spot among the stars. These two "days" are slightly different because the earth is in orbit around the sun, covering approximately one degree a day of sky. (There should be enough material attached to those to flesh out your Thread on rotation.)

 

 

How is any of this relevant to the discussion?

[frankglennjacobs@gmail.com]

Roger Dynamic Motion asked about rotation of objects.

 

He asked if we are near "the Black Hole," and whether the sun is at the center of the Galaxy and whether the protoplanetary disk was the Galaxy itself.

 

I am aware that I answered more than Roger asked, but he brought up the subjects.

Edited May 30, 2017 by frankglennjacobs@gmail.com

[Roger Dynamic Motion]

Roger Dynamic Motion brought in a consideration of "the Black Hole," and whether the sun is at the center of the Galaxy and whether the protoplanetary disk was the Galaxy itself.

 

I am aware that I answered more than Roger asked, but he brought it up.

 

 

 

Roger Dynamic Motion brought in a consideration of "the Black Hole," and whether the sun is at the center of the Galaxy and whether the protoplanetary disk was the Galaxy itself.

 

I am aware that I answered more than Roger asked, but he brought it up.

 

 

Just a few days ago, in response to another thread, I proved (as far as I can tell) to myself that if material that is originally spread out across a range of solar radii, with each piece originally pursuing its own independent orbit,

______________________________________

 

 

 

What is the meaning of Solar radii?

 

 

Edited May 30, 2017 by Roger Dynamic Motion

[frankglennjacobs@gmail.com]

Just jumping to conclusions, I would guess that it is the calculated distance from the center of the sun to its apparent surface.

[Roger Dynamic Motion]

Just jumping to conclusions, I would guess that it is the calculated distance from the center of the sun to its apparent surface.

[

Edited May 31, 2017 by Roger Dynamic Motion