Where Troy Once Stood

[Gaby]

Hope this now made things a bit clearer.

But you're mixing apples and oranges, so to speak. In order for your orange to do the Dzhanibekov effect, it has to have something akin to a butterfly nut inside of it.

It would work if the orange had the equivalent of a butterfly nut inside of it AND if the edible inner part of the orange "boiled", so this "butterfly nut" is free to move around to do its Dzhanibekov effect. Otherwise, the entire sphere with its butterfly nut is solidly held together as a single part. When the butterfly nut is free to move with something akin to a Dzhanibekov effect, the poles will change. The dots you painted can find themselves a new location, independent of the prior axis of rotation:

https://videos.files.wordpress.com/0QF3nivm/ecdos3-mp4.mp4

This is what deep Earth research is pointing at: heat released from the core butters up the mantle, which then facilitates the outer mantle + crust to move around in a semi-Dzhanibekov effect because the earth has something akin to an inner "butterfly nut" that facilitates such an event.

Q: (Gaby) TES (The Ethical Skeptic) has a hypothesis based on these blobs and posits that Earth's core and mantle dynamics drive periodic rotational instabilities, leading to true polar wander events.

[Background info: Exothermic Core-Mantle Decoupling - Dzhanibekov Oscillation (ECDO) Theory]

A: Partly involved, yes.

Q: (Gaby) He claims that a weakening of the core mantle magnetic coupling causes heat from the Earth's core into the mantle, excluding these blobs. This makes the rest of the mantle denser than the blobs, contributing to:

- Loss of current influence in the position of our geographic North Pole

- Increase in sea surface temperature and in the Earth's axis of rotation

- Shift in the planet's rotation around its maximum axis (the denser mantle)

- Increasing the chances of a True Polar Wander event with an axis of gyroscopic moment based upon the African blob.

A: Very close!

The two blobs and the two denser parts of the mantle is your "butterfly nut" inside the earth. It only happened because heat is being released from the inner core into a specific pattern favoring a gyroscope. Before, it was business as usual, the Earth spinning along its axis for thousands of years.

 

[SasaM]

But you're mixing apples and oranges, so to speak. In order for your orange to do the Dzhanibekov effect, it has to have something akin to a butterfly nut inside of it.

That's true for inherent instability of the system, but it should also work for solid bodies when being significantly perturbated from outside, like that nudge or perhaps cometary interactions, to get them out of stable rotation.

Dzanibekov effect is an extreme example, what I'm saying is that any significant perturbation from outside of the system can distrupt its rotation so to change the rotational axis orientation, like its precession and angle to the orbital plane, and axis position, that is location of the poles on the rotating body. No need per se for crustal movement to come into play for the location of the poles to change.

In case of the Earth, cometary interactions could in principle change the axis orientation and its position, that is move geographic poles out of their previous locations on the globe and change the precession angle, although these types of perturbations probably would not be strong enough to cause complete axis reversal like it happens in Dzanibekov effect due to the instabilities that are already there in the Earth's interior.

In case of an orange, a nudge or for example a friction introduced from outside of the rotating fruit would change its axis of rotation and where the poles are, though only temporarily if no significant mass redistribution would happen to change the moments of inertia of the orange body. In that case, after some time the rotation would return to its stable pattern if no new perturbations would happen.

In short, I am not disproving or invalidating ES hypothesis and theory, but just pointing out that rotational axis can change, with poles changing their positions, without the need for any crustal movement, just by being distrupted from outside like from outer space.

 

[Persej]

A few nights ago, I was watching a TV show on History Channel where they talked about how pyramids in Egypt were placed to represent stars in the Orion constellation. But they said that there is one thing that was unusual in that theory - the Orion constellation would have to be looked at upside down for that alignment to make sense. But perhaps in the past, during the construction of the pyramids, the Earth really was upside down?

 

[SasaM]

FWIW, here's what the AI Search Assist of DuckDuckGo on Vivaldi mobile said.

Q: can outside perturbation change rotational axis and position of the poles on the rotating body


Search Assist

Yes, outside perturbations, such as gravitational forces from other celestial bodies, can change the rotational axis and position of the poles on a rotating body. This phenomenon is part of what is known as precession, which involves slow changes in an astronomical body's rotational parameters. Wikipedia

Effects of Outside Perturbations on Rotational Axis​

Types of Perturbations​

• Gravitational Forces: External gravitational influences, such as those from nearby celestial bodies, can alter the rotational axis of a body. This is particularly relevant in astronomy, where the gravitational pull from the Moon and Sun affects Earth's rotation.
• Impact Events: Collisions with asteroids or comets can also change a body's rotational axis and position of its poles. Such impacts can impart significant angular momentum, leading to a shift in orientation.

Mechanisms of Change​

• Torque-Induced Precession: When an external torque is applied, it can cause the rotational axis to precess. This means the axis will trace out a cone over time, leading to changes in the position of the poles.
• Nutation: This is a smaller, periodic oscillation of the rotational axis that can occur due to external forces. It can affect the stability of the rotational axis and the position of the poles.

Implications for Earth​

Precession of the Equinoxes​

• Earth's rotational axis undergoes a slow change known as the precession of the equinoxes, which is influenced by gravitational interactions. This cycle takes about 26,000 years to complete, causing the positions of the poles to shift gradually.

Long-Term Changes​

• Over tens of thousands of years, external perturbations contribute to changes in Earth's axial tilt and orbital eccentricity, which are significant factors in climate changes and ice ages.

In summary, outside perturbations can indeed change the rotational axis and the position of the poles on a rotating body through various mechanisms, including gravitational forces and impact events.
Wikipedia

 

[axj]

Q: can outside perturbation change rotational axis and position of the poles on the rotating body

This is an imprecise question. Precession of the axis does not change the location of the geographical poles on the planet.

From Brave AI:

No, precession does not change the geographical poles on Earth. The precession of the Earth's axis refers to the slow, conical wobble of the rotational axis, which causes the direction it points in space to change over time. This movement affects the celestial poles—the points in the sky around which the stars appear to rotate—but it does not alter the geographic locations of the North and South Poles on the Earth's surface. The positions of the poles and equator on Earth remain fixed; only the orientation of the Earth's axis relative to the fixed stars changes.

 

[SasaM]

This is an imprecise question. Precession of the axis does not change the location of the geographical poles on the planet.

Well, in principle neither the nutation would change the position of the geographic poles, but then there is following image on the Wikipedia page about it:

with the caption saying:

Yearly changes in the location of the Tropic of Cancer near a highway in Mexico.

Then, on the Wikipedia page about Tropic of Cancer it says:

The Tropic of Cancer's position is not fixed, but constantly changes because of axial precession in the Earth's longitudinal alignment relative to the ecliptic, the plane in which the Earth orbits around the Sun.

and a bit later:

The distance between the Antarctic Circle and the Tropic of Cancer is essentially constant as they move in tandem. This is based on an assumption of a constant equator, but the precise location of the equator is not truly fixed.

If equator is "not truly fixed" implies that the poles are also not truly fixed.

So, on Wikipedia page about equator:

Precise location​

The precise location of the equator is not truly fixed; the true equatorial plane is perpendicular to the Earth's rotation axis, which drifts about 9 metres (30 ft) during a year.

In short, geographic poles have been changing their location even now as we speak.

I would appreciate very much if someone could show me how the change in rotational axis position in general, that is change in locations of geographic poles in particular, can come only from crustal movement, meaning that their drift mentioned above in relation to nutation also has to come from such a crustal movement.

Besides that, I'll give my best to not bother any more with this subject and drive the discussion here in the off topic direction.

 

[axj]

In short, geographic poles have been changing their location even now as we speak.

I would appreciate very much if someone could show me how the change in rotational axis position in general, that is change in locations of geographic poles in particular, can come only from crustal movement, meaning that their drift mentioned above in relation to nutation also has to come from such a crustal movement.

Yes, you are right that a minute amount of true polar wander does occur all the time. And it is even theorized that tens of millions years ago there was a 25 degree true polar wander without crustal displacement - that the rotation itself shifted (not an axial tilting) and as such changed the location of the geographical poles.

So what you are saying seems possible and it is even the preferred scientific explanation for true polar wander. However, it seems that crustal displacement may be the primary cause of true polar wander, especially if it is a large movement of the poles in a short time. We do not actually know if the minute yearly true polar wander is caused by crustal displacement or changes of the rotation itself.

It is a surprisingly complex topic. There are even two types of nutation ("rotation wobbles") and two different kinds of one of those nutation types. Anyone not confused yet?

 

[SasaM]

In short, geographic poles have been changing their location even now as we speak.

I would appreciate very much if someone could show me how the change in rotational axis position in general, that is change in locations of geographic poles in particular, can come only from crustal movement, meaning that their drift mentioned above in relation to nutation also has to come from such a crustal movement.

Besides that, I'll give my best to not bother any more with this subject and drive the discussion here in the off topic direction.

In conclusion and as a sort of closing argument, few bits about this so called polar motion (Wikipedia link).

Principle​

In the absence of external torques, the vector of the angular momentum M of a rotating system remains constant and is directed toward a fixed point in space. If the earth were perfectly symmetrical and rigid, M would remain aligned with its axis of symmetry, which would also be its axis of rotation. In the case of the Earth, it is almost identical with its axis of rotation, with the discrepancy due to shifts of mass on the planet's surface. The vector of the figure axis F of the system (or maximum principal axis, the axis which yields the largest value of moment of inertia) wobbles around M. This motion is called Euler's free nutation. For a rigid Earth which is an oblate spheroid to a good approximation, the figure axis F would be its geometric axis defined by the geographic north and south pole, and identical with the axis of its polar moment of inertia.

...

The observed angle between the figure axis of the Earth F and its angular momentum M is a few hundred milliarcseconds (mas). This rotation can be interpreted as a linear displacement of either geographical pole amounting to several meters on the surface of the Earth: 100 mas subtends an arc length of 3.082 m, when converted to radians and multiplied by the Earth's polar radius (6,356,752.3 m). Using the geometric axis as the primary axis of a new body-fixed coordinate system, one arrives at the Euler equation of a gyroscope describing the apparent motion of the rotation axis about the geometric axis of the Earth. This is the so-called polar motion.

Polar motion in arc-seconds as function of time in days (0.1 arcsec ≈ 3 meters).

Theory​

Annual component​

Figure 2. Rotation vector m of the annual component of polar motion as function of year. Numbers and tick marks indicate the beginning of each calendar month. The dash-dotted line is in the direction of the major axis. The line in the direction of the minor axis is the location of the excitation function vs. time of year. (100 mas (milliarcseconds) = 3.082 m on the Earth's surface at the poles)

There is now general agreement that the annual component of polar motion is a forced motion excited predominantly by atmospheric dynamics. There exist two external forces to excite polar motion: atmospheric winds, and pressure loading.

As can be read about polar motion, even without considering external torques, such as that nudge or cometary interactions, changing the locations of the geographic poles is thought to be related to forced motion, i.e. external forces coming from the atmosphere. Which suggests that significant distruptions from really outside of the planetary system would cause even larger changes in Earth's rotational axis position, where the poles are located on the globe, and very likely also its orientation to fixed stars.

As Gaby said in relation to determining the date of this year's lunar standstill; I rest my case.

It is a surprisingly complex topic. There are even two types of nutation ("rotation wobbles") and two different kinds of one of those nutation types. Anyone not confused yet?

Yeah, there's also a text about that, IRC, about Chandler wobble, in ECHCC.

 

[SasaM]

So what you are saying seems possible and it is even the preferred scientific explanation for true polar wander. However, it seems that crustal displacement may be the primary cause of true polar wander, especially if it is a large movement of the poles in a short time. We do not actually know if the minute yearly true polar wander is caused by crustal displacement or changes of the rotation itself.

True.

What all this recent back and forth discussion has yielded, OSIT, is a possibility that Posidonius' apparent errors in relative geographic positions of Rhodes and Alexandria, while calculating Earth's circumference (described in this post), might be attributed to later changes in Earth's rotational axis due to possibly cometary interactions, maybe even that one that presumably ended the Roman Empire, without necessarily invoking crustal displacement in the process.
The crustal displacement of course could have been involved, but does not need to be, as cometary interactions alone obviously can change both, Earth's rotational axis orientation AND its position, that is the locations of the geographic poles on the globe.

Me thinks that in the similar manner processes behind the potential crustal displacement, like ES hypothesis Gaby informed us about, can also change both, rotational axis position AND its orientation to fixed stars, by 'simply' changing the distribution of mass or density in the Earth's interior, which in effect affects the tensor of moment of inertia and by that also the direction of the principal axes of rotation of a solid body. But that's probably a discussion subject for some other time and place.