Question Does everything in space spin - does the Sun spin ?

[DOGGDADD]

Does the Sun rotate on an axis-does the Sun spin ?

 

[Wolfshadw]

Yes it does:

Solar Rotation Varies by Latitude - NASA

The Sun rotates on its axis once in about 27 days. This rotation was first detected by observing the motion of sunspots.

www.nasa.gov

-Wolf sends

Edit: Can't speak to everything, but as far as I know (AFAIK), everything does have a rotation.

 

[rod]

"Does the Sun rotate on an axis-does the Sun spin ?"

When it comes to the Sun rotation, quality telescopes using safe solar filters will show the Sun spins. Tracking sunspots do this. Today I viewed sunspot active region AR2824. https://www.spaceweather.com/

If a large sunspot holds together, in about 26 days or so, it will move around the Sun and reappear again. The source Wolfshadw cited says "The Sun rotates on its axis once in about 27 days. This rotation was first detected by observing the motion of sunspots. "

This is factual and readily verifiable. Since 01-May-2021 I viewed 6 sunspots, AR2818 - AR2824. The sunspots slowly move across the Sun compared to Jupiter's Great Red Spot. The GRS moves across Jupiter when I view using my telescopes in 4 hours or a bit more. Fascinating to watch rotation on the Sun and Jupiter and easy to see using good telescopes and safe solar filters. Mars in October last year was at opposition. Mars at telescope high power (I viewed at 216x) shows surface features and those features move across Mars too in the eyepiece while watching over several hours or more. Mars is spinning.

 

[Helio]

Rotation requires a reference frame, so sitting still I’m still rotating because the Earth is rotating me with it.

The Sun, being a gas ball, rotates at rates that vary with latitude. Deeper inside the Sun, it rotates like a solid.

 

[Catastrophe]

Does everything in space spin - does the Sun spin ?

Yes. Relative to something.

Cat

 

[David-J-Franks]

Rotation requires a reference frame, so sitting still I’m still rotating because the Earth is rotating me with it.

The Sun, being a gas ball, rotates at rates that vary with latitude. Deeper inside the Sun, it rotates like a solid.

Does everything in space spin - does the Sun spin ?

Yes. Relative to something.

Cat

Helio and catastrophe can you please check. it's just a thought but I don't think spin needs a reference frame or something relative to it to spin. I think spin is an absolute property. I say this because something spinning will have an internal centripetal force ( centrifugal force for non-scientists) to it, and that's an absolute value, regardless of whether it's relative to something else or not.

Yes, I also think most things are spinning, right from the components of atoms up to galaxies. To add my own personal thought, I actually think the whole contents of the big bang must be spinning as well. I say this, firstly because it's not bolted down to anything, laugh laugh, and therefore is absolutely without friction so it can move. also if it were not spinning that would mean it had 0 spin. 0 is an exact value, and so, because there's no such thing as 'exact' for something that is free to move it must be spinning laugh laugh again.

I suggest this could be considered as a contributing reason why expansion is observed everywhere in our observable universe. If the whole contents of the big bang were rotating then the centrifugal force would cause everything to fly outwards giving the appearance of expansion.

I say this because I believe the big bang contents is not the universe as per theory, and that is just simply an object that exists in its own right in a pre-existing space, and so is not all of space as per theory.

 

[Catastrophe]

David, just noticed this:
"Helio and catastrophe can you please check. it's just a thought but I don't think spin needs a reference frame or something relative to it to spin. I think spin is an absolute property. I say this because something spinning will have an internal centripetal force ( centrifugal force for non-scientists) to it, and that's an absolute value, regardless of whether it's relative to something else or not."

All spin must be relative. Just for starters, to make it simple, assume all planets (and moons, if you like) have the same ("upright") axis of rotation. Now periods of rotation differ enormously. From memory, the only similar ones are Earth and Mars.

If you have two planets with axes "upright", and they are close together, if their rotation periods are equal, they will always have the same relative aspects. Obviously, they are never close together and their rotation periods are not exactly equal. Even if there were exactly equal rotations, their distances vary continuously. Earth is about 8.3 and Mars 12.7 light minutes from the Sun. Thus the distance between Earth and Mars varies between 4.4 and 21 light minutes, so the appearances are different from those if they were close together.

OK. That is the simple case. In reality the axes are at different and the rotation periods are different. Thus there is absolutely no standard against which to measure rotation. Not even the Sun can provide a standard as it is not solid and different latitudes rotate at different periods.

You asked: "Helio and catastrophe can you please check. it's just a thought but I don't think spin needs a reference frame or something relative to it to spin."

The answer is that there is no single frame of reference - everything spins differently relative to everything else.

Cat

 

[Helio]

IIRC, there is still a debate about rotation. There is a famous case where a bucket of water is flung by a rope round and round in a universe with no mass, except for the bucket. The question is whether the water would creep up the sides? Mach,I think, said no.
I suppose a rotational can be independent, but to have meaning I would think you need references.

A modified Tychonic model has the Earth at the center. This rotational frame is not in violatiion of GR, surprisingly, but with all other motions, including our galaxy, our current model works much better.

 

[Catastrophe]

Helio, we on Earth, have proof that we are rotating with respect to the Sun. That proof is the existence of day and night. We know that (probably dozens, if not more planets, dwarf planets, moons, asteroids. TNOs etcetera, are rotating. There are no absolute rotations, but there are thousands of relative rotations - any object viewed from another object shows change of view of surface features. I cannot see any doubt whatsoever about this. It would be, to deny night and day.

Cat

P.S. Is not the bucket of water orbiting = revolving around, not rotation? The bucket is not turning on an axis, but orbiting a central point external to the bucket. It is like the Earth orbiting the Sun, not turning on its axis.

 

[David-J-Franks]

IIRC, there is still a debate about rotation. There is a famous case where a bucket of water is flung by a rope round and round in a universe with no mass, except for the bucket. The question is whether the water would creep up the sides? Mach,I think, said no.
I suppose a rotational can be independent, but to have meaning I would think you need references.

A modified Tychonic model has the Earth at the center. This rotational frame is not in violatiion of GR, surprisingly, but with all other motions, including our galaxy, our current model works much better.

Helio and Catastrophte,

First borrow a rotating space station, the type that provides artificial gravity, like the one in 2001 a space odyssey (Elon Musk might have one).

Catastrophe, take with you, Helio, a walkie talkie and some bathroom scales.

Leave Helio tethered outside the space station. You go in and close all the curtains so you can't cheat by looking at the stars. Then stand on the scales on the floor of the inside perimeter of the space station. The scales will register your weight.

If you know your mass, and the radius of the space station you can calculate your absolute rate of spin without looking out of the window, by using the formulae;

Force (centripital) = mass x velocity^2/radius

In this equation, the force, the mass and the radius are absolute values, so the velocity term must also be an absolute value.

As the curtains were closed, all the information Catastrophe had was obtained from inside the space station. So the answer was independent and not relative to anything outside. The spin of the space station is therefore an absolute value.

Suppose Helio has poor eyesight and can only see the space station but not any stars. When asked, Helio will swear the space station is not rotating. If Catastrophe, on the scales, tells Helio that he has a weight, then Helio must conclude that the space station is spinning and that he is going around with it.

Some might be confusing spin with revolving or orbiting. They are different things. Spin is where the axis of rotation passes through the body in question and revolving or orbiting is where the axis of rotation is external.

Without thinking too hard, I think the same reasoning should apply to orbits as well. Since they are gravitationally bound a system might behave as a single spinning object.

I suppose a rotational can be independent, but to have meaning I would think you need references.

I think the meaning is that Catastrophe has an independant fixed weight regardless of what's going on outside and that he can communicate it.

 

[Catastrophe]

Hole in one! (Golfing term, meaning 'right on')!

"Some might be confusing spin with revolving or orbiting. "

Cat

Vide all I posted about spin (about an axis - not about orbiting).

 

[Catastrophe]

Just to remind you good folks, this thread is entitled:

Does everything in space spin - does the Sun spin ?

Cat

 

[David-J-Franks]

Helio, we on Earth, have proof that we are rotating with respect to the Sun. That proof is the existence of day and night. We know that (probably dozens, if not more planets, dwarf planets, moons, asteroids. TNOs etcetera, are rotating. There are no absolute rotations, but there are thousands of relative rotations - any object viewed from another object shows change of view of surface features. I cannot see any doubt whatsoever about this. It would be, to deny night and day.

Cat

P.S. Is not the bucket of water orbiting = revolving around, not rotation? The bucket is not turning on an axis, but orbiting a central point external to the bucket. It is like the Earth orbiting the Sun, not turning on its axis.

There are no absolute rotations, but there are thousands of relative rotations

The more I think about it the more I think the opposite is true, i.e all rotations are absolute, because rotation causes an absolute value of internal centripital force proportion to its rotation speed, dependent only on the mass and radius of the object, which can be measured or calculated. It's not dependent on what any outside observers see or measure.

any object viewed from another object shows change of view of surface features.

Yes, but that doesn't disprove the object being viewed doesn't have an absolute rate of spin. How fast you are moving doesn't change the fixed internal centripital force of the object.

You're right to bring the bucket of water up. My research showed that spin and orbiting or revolving are both different kinds of rotation. I still think both are absolute values.

Apologies in case I've denied night and day for you.

 

[Catastrophe]

David, there is very little ABSOLUTE in this world and, sorry, to disagree with you, but spin (imho) ain't one of them. Absolute with respect to what absolute reference standard?
A spinning object may be stationary and surrounded by a spinning Universe. (Careful!)

"My research showed that spin and orbiting or revolving are both different kinds of rotation. I still think both are absolute values." No. Sorry. Quite different - imho. My emphasis.

Please think again before night and day alternate too many times. They do, you know.

Cat

 

[Catastrophe]

Well, sorry, I will continue.
We know that the Sun spins differently at different latitudes. The core also spins differently. It is not an absolute frame of reference. Just suppose that the Sun did spin uniformly despite latitude or composition. There is an absolute frame of reference? No.
Just consider a trillion such "Suns" all spinning uniformly.
Where is the absolute frame of reference? Which "Sun" is the correct one?

Cat

To continue (if t'were necessary?) consider Earth orbiting Sun. Assume 'perfect' Sun as above.
The fact that Earth spins in approx 24 hours has no connection with the time it takes to orbit the Sun. (Quote me the Kepler Law which contradicts this - or any other law).
So Earth spins once in 24 hours wrt Sun. Now add Venus, which spins retrograde. Which is absolute - Sun, Earth or Venus? You have 3 relative spins S-E, S-V, and E-V. Which is absolute? And if you say Sun - then see above - which "Sun"?

 

[Helio]

I’m using a phone so I will be brief.

The point of the bucket was to get background gravity into the picture. In GR, it is valid to say the space station is still and the universe is rotating around it. That’s relativity.

Of course, it quickly becomes tricky as to how forced are found to fit the appearances. These are call fictious forces.

 

[Catastrophe]

"it is valid to say the space station is still and the universe is rotating around it."

Trillions of universes rotating around billions of planets (and moons, and . . . . . . )

Reduction ad absurdum.

Trillions of universes rotating fictitiously around billions of . . . . . . . . .

Q. E. D.

Cat

Quote
Rotating Coordinates in Relativity
Relativity is built on the existence of inertial frames. . . . . . . . . . The first thing relativity does with an inertial frame is define coordinates for it. These coordinates are meaningful: in particular, the time coordinate is constructed such that two events in the frame that have the same time coordinate will be measured by all inhabitants of the frame to occur at the same time. Other coordinates can be constructed that don't obey this idea. These other coordinates have limited value because, in particular, two events that occur simultaneously might be allocated different values of such a time coordinate.
Quote

Helio, what is your take on this?

* The Earth spins once in 24 hours wrt Sun. Now add Venus, which spins retrograde. Which is absolute - Sun, Earth or Venus? You have 3 relative spins S-E, S-V, and E-V. Which is absolute? And if you say Sun - then see above - which "Sun"? *

 

[Catastrophe]

We are getting horribly off track here imho. The topic is:
Does everything in space spin - does the Sun spin ?
Post #1 asks: "Does the Sun rotate on an axis-does the Sun spin ?" My emphasis.

May I respectfully suggest that if anyone wants to discuss swinging buckets or other matters relating to one body swinging or orbiting around another, they might like to consider starting an appropriate thread. The question here is not: does the Earth orbit around the Sun?

The Earth, and all astronomical bodies spin on their axes. The Earth spins on its axis in approximately 24 hours. The Earth also orbits the Sun in one year. If anyone thinks that these are the same, then I believe we should agree our definitions before proceeding further. Does this sound a good common sense solution? A little polite agreement here can save pages of confused "discussion" otherwise.

Cat

 

[David-J-Franks]

Just to remind you good folks, this thread is entitled:

Does everything in space spin - does the Sun spin ?

Cat

Hi Catastrophe,

I don't think it's going off-topic too much, I guess this was aimed at me.

All I've been doing is responding to your post - no 5 as below;

Does everything in space spin - does the Sun spin ?

Yes. Relative to something.

Cat

The "Yes. Relative to something." reply was a red flag for me . I think it's fair to challenge something I don't agree with, also it's still about spin.

Since there's still something in common with the posts, I would prefer to keep the continuity of thought in this thread. Also, it looks like this thread would die off soon anyway.

If you still want to move it, then OK, let us know. Unless I hear from you, I'll carry on here for now Lots more to say yet

 

[Catastrophe]

David, nothing is aimed against you. I do not make personal attacks. What I find (honestly) abhorrent is confusing the idea of spin, which is common to every understood body in the observed universe, spinning around its own axis, with moving around a central point. viz orbiting around another body. Totally different matters.

I do not want to get into trouble with repetition, but I find it impossible for anyone to respond to the following:

THIS IS WHAT THE OP ASKED:
Does everything in space spin - does the Sun spin ?
Post #1 asks: "Does the Sun rotate on an axis-does the Sun spin ?" My emphasis.

May I respectfully suggest that if anyone wants to discuss swinging buckets or other matters relating to one body swinging or orbiting around another, they might like to consider starting an appropriate thread. The question here is not: does the Earth orbit around the Sun?

The Earth, and all astronomical bodies spin on their axes. The Earth spins on its axis in approximately 24 hours. The Earth also orbits the Sun in one year. If anyone thinks that these are the same, then I believe we should agree our definitions before proceeding further. Does this sound a good common sense solution? A little polite agreement here can save pages of confused "discussion" otherwise.

Do we have a problem in distinguishing between "day and night" and "year"?
That is, between spinning and orbiting. Spin = day and night, orbit . year?

I really do believe we should sort out our definitions/ assumptions. PLEASE

Please, David, there is nothing whatsoever personal here. "No good wars." etcetera.
Please can we agree on some premises?

I was serious about this thread.

THIS IS WHAT THE OP ASKED:
Does everything in space spin - does the Sun spin ?
Post #1 asks: "Does the Sun rotate on an axis-does the Sun spin ?" My emphasis.

If you want to discuss "years" instead of "day and night" - I believe this belongs elsewhere. If I start a thread "spinning or orbiting" or something you choose, I will join you there. I think the OP should have the choice here - spin.

With sincere friendly wishes for a good discussion,

Cat

OK. I agree asteroids may "tumble" around a constantly changing axis. Not really relevant.

 

[Catastrophe]

David, a key seems to be:
'The "Yes. Relative to something." reply was a red flag for me . I think it's fair to challenge something I don't agree with, also it's still about spin.'

That speaks to definitions, so let's try and clear it up.

I cannot see the problem with everything spinning relative to something.
Earth spins relative to Sun, hence day and night.
Venus spins retrograde. Relative to Sun, its spin is different. Venus spins relative to Earth - maybe better to say Earth spins relative to Venus. All spin is relative to an observer situated on another body (or anywhere). What is wrong with that?

Cat

 

[David-J-Franks]

David, nothing is aimed against you. I do not make personal attacks. What I find (honestly) abhorrent is confusing the idea of spin, which is common to every understood body in the observed universe, spinning around its own axis, with moving around a central point. viz orbiting around another body. Totally different matters.

I do not want to get into trouble with repetition, but I find it impossible for anyone to respond to the following:

THIS IS WHAT THE OP ASKED:
Does everything in space spin - does the Sun spin ?
Post #1 asks: "Does the Sun rotate on an axis-does the Sun spin ?" My emphasis.

May I respectfully suggest that if anyone wants to discuss swinging buckets or other matters relating to one body swinging or orbiting around another, they might like to consider starting an appropriate thread. The question here is not: does the Earth orbit around the Sun?

The Earth, and all astronomical bodies spin on their axes. The Earth spins on its axis in approximately 24 hours. The Earth also orbits the Sun in one year. If anyone thinks that these are the same, then I believe we should agree our definitions before proceeding further. Does this sound a good common sense solution? A little polite agreement here can save pages of confused "discussion" otherwise.

Do we have a problem in distinguishing between "day and night" and "year"?
That is, between spinning and orbiting. Spin = day and night, orbit . year?

I really do believe we should sort out our definitions/ assumptions. PLEASE

Please, David, there is nothing whatsoever personal here. "No good wars." etcetera.
Please can we agree on some premises?

I was serious about this thread.

THIS IS WHAT THE OP ASKED:
Does everything in space spin - does the Sun spin ?
Post #1 asks: "Does the Sun rotate on an axis-does the Sun spin ?" My emphasis.

If you want to discuss "years" instead of "day and night" - I believe this belongs elsewhere. If I start a thread "spinning or orbiting" or something you choose, I will join you there. I think the OP should have the choice here - spin.

With sincere friendly wishes for a good discussion,

Cat

OK. I agree asteroids may "tumble" around a constantly changing axis. Not really relevant.

Please give me chance to catch up , you know I'm a slow plodder and like to go down the thread in order.

Anyway, because things need clearing up I'll start with this post and then jump back to where I was.

First can I say it's not me that's confused by spin and orbit, if you remember back to post 10, it was me that first suggested they were both different.

OK, some definitions;

What I find (honestly) abhorrent is confusing the idea of spin, which is common to every understood body in the observed universe, spinning around its own axis, with moving around a central point. viz orbiting around another body. Totally different matters.

No, not totally different matters. Spin and orbit both come under the same general category of 'ROTATION'. The only difference is that with spin the axis of rotation is through the body, and with orbit, a common axis of rotation is external to the body. Both are rotations, and I suspect a lot of the maths is similar to both. So not really off-topic.

The Earth spins on its axis in approximately 24 hours. The Earth also orbits the Sun in one year. If anyone thinks that these are the same, then I believe we should agree our definitions before proceeding further.

They both fall under the catorgory of rotation, and I think the same maths.

Do we have a problem in distinguishing between "day and night" and "year"?
That is, between spinning and orbiting. Spin = day and night, orbit . year?

Yes, different, but both are forms of rotation.

I think the OP should have the choice here - spin.

I haven't deviated from spin, other than in one sentence. My space station idea was all about spin and try to prove that it's absolute.

Give me some time now, and I'll go back up the thread and start addressing some of the examples you gave. I might have to go for a meal first, so don't hold your breath

 

[Catastrophe]

David, have a good break and enjoy your meal.

Nothing more to say until you are ready to resume

There is one absolutely fundamental difference. Spin involves one body, orbit involves two bodies. Of course, either may be observed from outside.

Cat

 

[David-J-Franks]

Catastrophe and Helio,

No one has tried to argue against my space station example or the equation in it.

Most have responded by putting up counterarguments and examples. Before I address these, will someone comment on my space station example or the equation in it, please. Will you say why, if you think it's wrong. I'll put the equation here again, can you please have a hard look at it again. Quote from my space station example, post 10 above;

If you know your mass, and the radius of the space station you can calculate your absolute rate of spin without looking out of the window, by using the formulae;

Force (centripital) = mass x velocity^2/radius

In this equation, the force, the mass and the radius are absolute values, so the velocity term must also be an absolute value.

As the curtains were closed, all the information Catastrophe had was obtained from inside the space station. So the answer was independent and not relative to anything outside. The spin of the space station is therefore an absolute value.

Note the force term in the equation is from the bathroom scales on which Catastrophe was standing.

To me, it looks rock solid, black and white, am I missing something? I'm aware you could nitpick by bringing in minuscule relativistic effects, but I'm hoping you'll stick to the spirit of the discussion.

I'm not pressurising you, so if you don't want to respond here, just say pass and I'll continue from a different angle.

When you, Catastrophe, have responded here one way or another, I'll start addressing your comments from post 14 downwards

 

[Catastrophe]

I am not playing games like 'you do this if I do that'.

I have made my case, you choose, sadly it seems, to prevaricate, I have asked to clarify assumptions - specifically - we just seem to speak different languages.

There are no winners. We shall both enjoy our assumptions.
Have fun. Live long and happily.

Best wishes,

Cat