[Bobby Shafto]

There is no description or explanation of the bi-polar model on the TFES wiki. (If there is, I couldn't find it.)

If the bi-polar model is the preferred model, having replaced the north polar azimuthal model most associated with flat earth belief, I think this deficiency merits attention. I know it's not my charter to worry about how TFES presents a defense of a flat earth, but it's come to my attention that some of my critiques of "flat earth theory" (if there is such a thing) is based on a misunderstanding of what the Society currently supports.

I've read through some of the older discussion topics that delve into a bi-polar model of a flat earth, but rather than resurrect any of them, I thought it might be better to start fresh. And I've been reading the Sea-Earth Globe publication that may have been what motivated the Flat Earth Society to elevate a bi-polar model over a monopole one. I also see extensive argument by Sandokahn for his own passionate version/explanation of bi-polarism.

I don't think a bi-polar model is zetetically supportable, but I think both I and TFES might benefit from a discussion about it: the Society so that it can consider drafting an explanation of the model for the public and me so that I know if I'm understanding it correctly and investigate it properly.

Before I had read the Zetetes publication, (and I probably haven't scratched the surface of Sandokahn's writings),  I drew this up to start my questioning:



It was impressed upon me in another discussion topic that the bi-polar map(s) found on the wiki are notional and that there is no map. Rather, the bi-polar concept is but a model. So I drew this up without any map characteristics. I don't understand the model mechanism for the sun's shift from a northern hemiplane transit to a southern hemiplane. Here, I have the diamond marking the start of the sun's path on the day before the September Equinox. The sun at this point is slightly north of the equator. It then travels around the northern pole at maximum distance until reaching the centroid, the point at which it intersects with the equator. That is the point of equinox. Then, the next 24 hours it's path is the mirror of the previous day, but now around the southern hemiplane's perimeter, until reach the approximate location shown by the star icon.

That's a 48-hour journey bracketing the point of equinox. And the (angular?) distances above and below the equator are exaggerated, as is the distance from the perimeter since I don't know exactly how that should work. The equator, in particular, is confusing since during day of equinox the sun follows a path along the equator; but in a bi-polar model, that line (if that's what the equator is) is split between the far reaches of the north and south hemiplane. I also just guessed and rounded the corners at the left and right edges of the equator, uncertain how the sun makes that bend...assuming it even is an actual bend.

The document previously linked offers this graphic with accompanying explanation that is, at least for me, rife with problems:



I kind of hope this doesn't wind up being a bunch of round earthers piling on with criticism of these model variants. Not to discourage criticism because that's how ideas are burnished, but this shouldn't be round earthers doing the work to "murder board" and refine a bi-polar model. If there's already an existing articulation of the current, preferred model, point me to it. Else, can we talk it through and see where the model stands?

[titidam]

This post is definitely needed. The model needs to be detailed.

There can't be any discussion about Flat Earth if every argument stumbles on the fact that TFES supports a mostly undescribed model.

Even the wiki is misleading on this subject, describing the monopole model on every single page under Form and Magnitude. Except for the 2 maps which we are told don't represent anything.

[Tom Bishop]

I have felt that this was interesting, and would perhaps provide a clue for constructing a Flat Earth model. The "equal day and night happens on the equinox" thing is a myth, and is time and location dependent.

https://pingpdf.com/pdf-ancient-observatories-stanford-solar-center-stanford-university.html

Calculating the Equinoxes

Most dictionaries erroneously define the equinox as: “the time or date (twice each year) at which the Sun crosses the celestial equator, when day and night are of equal length (about September 22 and March 20)”. However, there is no place on Earth where the day and night are of equal length on the given days.

Latitude Determines Day Length

In fact, latitude determines day length. Even if day and night aren’t exactly equal on the day of the equinox, there are days when day and night are both very close to 12 hours. However, this date depends on the location’s latitude, and can vary by as much as several weeks. The table shows approximate dates for when day and night are as similar as possible according to latitude.

How could there never be an equal day and night throughout the year on the equator for say... a round earth? And the latitudes near it, to the North and South of the equator, having equal day and night weeks away from the equinox? It doesn't really makes any sense.

However, the indication that 45 degrees N has its equal days several days after September Equinox and that 45 degrees S has its equal days several days before the equinox, and vice-versa for the March Equinox, suggests to me some sort of bi-polar model where the spotlight of the sun is moving from one hemiplane to the next, if that is indeed what is happening.

Unfortunately this source does not tell us which longitude(s) this data is from. It is quite surprising, nonetheless, since we have been told only about one million times that the earth experiences equal day and night on the equinox.

[titidam]

The refraction of the Sun by the atmosphere increases the duration of dawn, slightly tweaking daytime length including at the equinox. This variation depends on many factors like temperature and humidity.

But if we're not going to criticize bi-polar Earth in this thread, you're not going to criticize Round Earth. Let's be constructive and define the model.

[edby]

Any such model must explain the movements of the stars. The significant observations here are (1) their positions remain fixed with respect to one another and (2) they appear to move as a fixed system around the earth. I.e. Orion remains the same shape throughout the night, but appears to move around the sky, likewise all the other constellations.

[AATW]

How could there never be an equal day and night throughout the year on the equator for say... a round earth? And the latitudes near it, to the North and South of the equator, having equal day and night weeks away from the equinox? It doesn't really makes any sense.

without looking into this in any detail I'm going to say it's related to the earth's tilt with respect to the sun. If the axis of rotation was perpendicular to the direction of the light from the sun then we'd get equal days and nights all year round. The angle away from the perpendicular combined with the orbit of the earth around the sun causes the variation in day length as we go through the year.

It is quite surprising, nonetheless, since we have been told only about one million times that the earth experiences equal day and night on the equinox.

A rare agreement from me, that is what I understood an equinox to be too. I believe that does actually occur at most latitudes but the date of it varies. I didn't realise it varied as much as that document shows though.

[Curious Squirrel]

How could there never be an equal day and night throughout the year on the equator for say... a round earth? And the latitudes near it, to the North and South of the equator, having equal day and night weeks away from the equinox? It doesn't really makes any sense.

without looking into this in any detail I'm going to say it's related to the earth's tilt with respect to the sun. If the axis of rotation was perpendicular to the direction of the light from the sun then we'd get equal days and nights all year round. The angle away from the perpendicular combined with the orbit of the earth around the sun causes the variation in day length as we go through the year.

It is quite surprising, nonetheless, since we have been told only about one million times that the earth experiences equal day and night on the equinox.

A rare agreement from me, that is what I understood an equinox to be too. I believe that does actually occur at most latitudes but the date of it varies. I didn't realise it varied as much as that document shows though.

I would note https://www.timeanddate.com/astronomy/equinox-not-equal.html has the same chart (or at least a similar one) and explains why the equator never technically has a 12 hour day, as a day starts when the first edge of the sun peeks over the horizon, and ends then it vanishes completely, thus adding extra minutes to even the day of the equinox. Refraction also plays a part, and adds at least 6 minutes to every day everywhere on Earth. But I believe we're getting heavily off-topic here. What does there not *technically* being a day with 12 hours of daylight on the equinox at the equator have to do with attempting to create a bi-polar model?

[markjo]

I have felt that this was interesting, and would perhaps provide a clue for constructing a Flat Earth model. The "equal day and night happens on the equinox" thing is a myth, and is time and location dependent.

Tom, if you really want to get pedantic, the equilux is when there is equal daylight and night.  As previously noted, atmospheric refraction can cause this equal day/night phenomenon to occur a few days before or after the equinox, depending on your location.

[Bobby Shafto]

Edited:

The etymology of the word is "equal+night" but Equinox as it is used (and as we should be using it) is not defined by day/night equivalence. It's the moment when the sun's zenith over the earth reaches the equator.

I do think that's an important concept to make clear since I think it will be important for development of an actual bi-polar model and especially any map based on that model.