<p>That does not happen. That cannot happen on grounds of conservation of angular momentum.</p>
<p>You might confuse this with a text talking about the Sun's magnetic field which undergoes a constant change and reverses polarity roughly every 11 years. You do see this <a href="https://en.wikipedia.org/wiki/Solar_cycle" rel="noreferrer">cycle in magnetic activity</a> easily by means of number of Sunspots and where they occur on the Sun.</p>

CC BY-SA 4.0
2022-08-08T14:43:18.270Z
A minor nit:  you can conserve AngMomentum and reverse the rotation relative to the planetary planne by rotating the sun's axis of rotation 180 degrees.  (You'd have to have a little bit of angular momentum in *that* plane, of course).
Carl Witthoft
CC BY-SA 4.0
2022-08-08T15:02:23.607Z
@CarlWitthoft Yeah, according to some theories, that is what happened to planet Venus, I guess!
apk
CC BY-SA 4.0
2022-08-08T16:50:59.153Z
@CarlWitthoft no, you can't. Any change in the axis of rotation is a change in angular momentum, it can only be done by exchanging momentum with some other object.
Christopher James Huff
CC BY-SA 4.0
2022-08-08T17:32:09.460Z
@ChristopherJamesHuff But if you start out with some angmom on that axis, it remains.  Granted that probably leads to a smooth continuous precession of the main polar axis.
Carl Witthoft
CC BY-SA 4.0
2022-08-08T17:34:33.683Z
That will be nutation. Precession requires an external force as a torque on the angular momentum which will not be significantly present for the sun
planetmaker
CC BY-SA 4.0
2022-08-08T18:56:08.977Z
Even nutation is a result of forces from other objects. Internal forces from fluid currents that differ from the overall rotational motion or other changes in mass distribution can also cause temporary variations, but they can not change the overall angular momentum. Flipping the axis 180 degrees involves a change by double the initial angular momentum, it'd violate conservation of momentum by twice as much as rotation simply spontaneously halting.
Christopher James Huff
CC BY-SA 4.0
2022-08-08T20:23:47.753Z
Turns out we can kind of do this with a solid object, which the sun most definitely is _not_. https://www.youtube.com/watch?v=1x5UiwEEvpQ
Joshua
CC BY-SA 4.0
2022-08-08T20:33:54.997Z
How does the Dzhanibekov effect relate to this answer? https://youtu.be/1VPfZ_XzisU?t=7 In short this video demonstrates a complete 180 degree reversal of the axis of rotation under zero external force, conserving angular momentum.
Beanluc
CC BY-SA 4.0
2022-08-09T00:05:24.467Z
Effects like the Dzhanibekov effect depend on radically different moments of inertia along different axes that can transfer the angular momentum.  Note that the rotation direction is still the same relative to the external universe, just the physical orientation of the object has inverted and is thus locally spinning the "other way".  In no way would this result in the object shifting from prograde to retrograde, which are external measures of direction.
throx
CC BY-SA 4.0
2022-08-09T17:47:52.717Z
@Beanluc the axis of rotation is not changing in that video.
Christopher James Huff
CC BY-SA 4.0
2022-08-08T10:19:58.347Z
2022-08-08T10:19:58.347Z
planetmaker
<p>Prograde means rotating in the same direction in which most of the planets in our solar system rotate, which is counterclockwise, and retrograde rotation means the opposite, i.e., clockwise rotation.
I do not remember the source, but somewhere I had read that Sun continues shifting between prograde and retrograde rotation. The rotation will be prograde for a particular period of the interval; after that, it will be retrograde and then again prograde. I do not remember exactly where I had read this. But now, when I search on google if this is true, I am not getting any relevant information. Now I doubt whether this is indeed true or not. Can someone help me with this?</p>
<p>Note: I am talking about retrograde rotation, not retrograde orbit.</p>

<the-sun><solar-system><rotation>
Does the Sun shift periodically between prograde and retrograde rotation about its axis?
apk
# Does the Sun shift periodically between prograde and retrograde rotation about its axis?

(Asked by: username_0 on 2022-08-08)

Prograde means rotating in the same direction in which most of the planets in our solar system rotate, which is counterclockwise, and retrograde rotation means the opposite, i.e., clockwise rotation.
I do not remember the source, but somewhere I had read that Sun continues shifting between prograde and retrograde rotation. The rotation will be prograde for a particular period of the interval; after that, it will be retrograde and then again prograde. I do not remember exactly where I had read this. But now, when I search on google if this is true, I am not getting any relevant information. Now I doubt whether this is indeed true or not. Can someone help me with this?

Note: I am talking about retrograde rotation, not retrograde orbit.

**Tags:** the-sun, solar-system, rotation


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## 1 answers

### Answer by username_1 on 2022-08-08. Score: 23 | Accepted answer

That does not happen. That cannot happen on grounds of conservation of angular momentum.

You might confuse this with a text talking about the Sun's magnetic field which undergoes a constant change and reverses polarity roughly every 11 years. You do see this [cycle in magnetic activity](https://en.wikipedia.org/wiki/Solar_cycle) easily by means of number of Sunspots and where they occur on the Sun.

> **Comments:**
> **username_2**: A minor nit:  you can conserve AngMomentum and reverse the rotation relative to the planetary planne by rotating the sun's axis of rotation 180 degrees.  (You'd have to have a little bit of angular momentum in *that* plane, of course).  
> **username_0**: @username_2 Yeah, according to some theories, that is what happened to planet Venus, I guess!  
> **username_3**: @username_2 no, you can't. Any change in the axis of rotation is a change in angular momentum, it can only be done by exchanging momentum with some other object.  
> **username_2**: @username_3 But if you start out with some angmom on that axis, it remains.  Granted that probably leads to a smooth continuous precession of the main polar axis.  
> **username_1**: That will be nutation. Precession requires an external force as a torque on the angular momentum which will not be significantly present for the sun  
> **username_3**: Even nutation is a result of forces from other objects. Internal forces from fluid currents that differ from the overall rotational motion or other changes in mass distribution can also cause temporary variations, but they can not change the overall angular momentum. Flipping the axis 180 degrees involves a change by double the initial angular momentum, it'd violate conservation of momentum by twice as much as rotation simply spontaneously halting.  
> **username_4**: Turns out we can kind of do this with a solid object, which the sun most definitely is _not_. https://www.youtube.com/watch?v=1x5UiwEEvpQ  
> **username_5**: How does the Dzhanibekov effect relate to this answer? https://youtu.be/1VPfZ_XzisU?t=7 In short this video demonstrates a complete 180 degree reversal of the axis of rotation under zero external force, conserving angular momentum.  
> **username_6**: Effects like the Dzhanibekov effect depend on radically different moments of inertia along different axes that can transfer the angular momentum.  Note that the rotation direction is still the same relative to the external universe, just the physical orientation of the object has inverted and is thus locally spinning the "other way".  In no way would this result in the object shifting from prograde to retrograde, which are external measures of direction.  
> **username_3**: @username_5 the axis of rotation is not changing in that video.  

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