[JHelzer]

The https://wiki.tfes.org/Southern_Celestial_Rotation page has the following question and answer

Q. How can two people on opposite sides of the earth in Australia and South America both see the same South Pole Stars simultaneously?
A. Since those areas are many hours apart from each other, when it is night or dusk for one area it is likely day or dawn for the other. It is questioned whether it is the case that those observers see the same stars simultaneously. Due to the time difference it may be that they see the stars alternately.

Can we discuss a better answer?  During the weeks surrounding the solstice in December this answer is true and works great, but in June the hours of darkness on the southern coast of Australia and South America are lengthened to the point that they do indeed have simultaneous viewing of the same stars.  I used https://www.timeanddate.com/sun/south-africa/cape-town to compare the nautical twilight hours in Cape Town, South Africa to Melbourne, Australia on June 14th, 2020 and there are over 3 hours of simultaneous night time viewing at those locations.

What would be a better answer to this question?

[Tom Bishop]

You pointed out a small date and time where you think the stars will be visible simultaneously.

You then assume that you are correct that those stars can be seen simultaneously.

You then ask us to come up with a different explanation because you are going to go ahead and assume that your assumption is correct.

Do you see a flaw there?

[JHelzer]

I do see the flaw you are talking about.  I did not mean to discuss the assumption that the same stars can be seen.  I specifically want to talk about the answer which states that there may not be the opportunity of darkness to view the stars simultaneously.  I don't like that part of the answer because it is known that there are times when the sky is sufficiently dark to see stars at the locations mentioned in the wiki answer.

Here is the data I used.  Hopefully there are no errors in my math.

Location	Date	Nautical Twilight	UTC Conversion
Cape Town, South Africa	June 14, 2020	6:42pm - 6:50am	20:42 - 08:50
Melbourne, Australia	June 14, 2020	6:09pm - 6:31am	05:09 - 17:31

This data demonstrates that in June from UTC 05:09 to 08:50 (3 hr 41 min) there is darkness in both locations sufficient to see stars.

[Alvin]

What about the southern cross, that's visible at the time and date JHelzer gave.

[SteelyBob]

You pointed out a small date and time where you think the stars will be visible simultaneously.

It's not 'small' - it's a substantial portion of darkness, over three hours in the example used, where it is dark simultaneously in two parts of the world that are separated by roughly 90 degrees of longitude. The same is also true of South America and South Africa - I just checked on Google for today and it shows sunset tonight in Buenos Aires is at 2310 UTC, with sunrise in Johannesburg, South Africa not occurring until 0327 UTC - that's a similar overlap.

Whilst it's not easily viewed without a dark sky and ideally a telescope, Sigma Octantis is almost perfectly aligned with due south, and appears at an altitude equal to the observer's latitude in the Southern hemisphere. So on a dark night, our observer in Buenos Aires would look due south and about 35 degrees up, and our friend in Johannesburg would look south and 26 degrees up, and they would be looking at the same star, stationary in the night sky, with all the others appearing to rotate around it, for around four hours or so at the same time.

There's lots of ways of verifying that, and of course one doesn't even need to go to such extreme distances for this observation to be problematic for FET. If you just got two people a few hundred miles apart in, say Australia, to observe Sigma Octantis at the same time they would both measure it as being on the same true heading - this could not happen on the monopole FE, as our observers would be looking in slightly different directions with their backs to the north pole.

[edited to add 'slightly' in the last sentence]

[JHelzer]

Many thanks for the additional support for the need to change the answer in the wiki. The underlined wording below is what I am suggesting needs to be changed.

A. Since those areas are many hours apart from each other, when it is night or dusk for one area it is likely day or dawn for the other. It is questioned whether it is the case that those observers see the same stars simultaneously. Due to the time difference it may be that they see the stars alternately.

Does the Flat Earth Community have any suggestions for a better answer?  Perhaps something about the bipolar FE model would be a better direction.

[Tron]

Its my understanding that people in northern latitudes see a different set of stars then people in the south.   A height and location difference could explain this on a flat earth.

[JHelzer]

Its my understanding that people in northern latitudes see a different set of stars then people in the south.

Yes.  Some stars and constellations (Ursa Minor) are visible only in northern locations, some stars and constellations (Southern Cross) are visible only in southern locations, and some stars and constellations (Orion) are visible to both northern and southern locations.

Circumpolar constellations like Ursa Minor and Southern Cross can be seen year round, while equatorial constellations like Orion are seasonal.

With all of this information about viewing stars so well established, why does the wiki say things like "It is questioned whether it is the case" and "it may be that they see stars alternately"? It is known that "it is the case" and it is known that there are times and seasons that stars are seen simultaneously.

I enjoy Flat Earth Theory, and I enjoy good arguments about it, but this particular entry in the wiki, needs to be revised.  It is not a good flat earth explanation.

[SteelyBob]

Its my understanding that people in northern latitudes see a different set of stars then people in the south.   A height and location difference could explain this on a flat earth.

That is correct. Even more significantly, which stars you can see, and when and where in the sky they will be can be perfectly predicted by your latitude and longitude. I have never seen a remotely credible explanation for how the stars appear in FET.

[RazaTD]

I am also worried that the mono polar flat earth model is unable to explain this. I have recently asked in another thread about this issue maybe some people from there might have better ideas.

[JHelzer]

You pointed out a small date and time where you think the stars will be visible simultaneously.

You then assume that you are correct that those stars can be seen simultaneously.

You then ask us to come up with a different explanation because you are going to go ahead and assume that your assumption is correct.

Do you see a flaw there?

Using Tom's answer as a starting place the wiki answer could be changed as follows:

Q. How can two people on opposite sides of the earth in Australia and South America both see the same South Pole Stars simultaneously?

A. The stars in the night sky are only visible simultaneously in these locations during a few months of the year.  In those conditions it is questioned whether it is the case that the observers actually see the same stars simultaneously.

[SteelyBob]

Using Tom's answer as a starting place the wiki answer could be changed as follows:

Q. How can two people on opposite sides of the earth in Australia and South America both see the same South Pole Stars simultaneously?

A. The stars in the night sky are only visible simultaneously in these locations during a few months of the year.  In those conditions it is questioned whether it is the case that the observers actually see the same stars simultaneously.

I'd suggest that the question should focus on the actual singular pole star, Sigma Octantis, and not 'stars', in order to avoid a tedious sidebar debate about what time and in what place the constellations like the southern cross can actually be seen. They may well be visible in those two continents at the same time, but if we focus on Sigma Octantis we don't need to worry about that, as it remains perfectly fixed in the sky and is therefore always visible south of the equator as long as darkness and clear skies permit it. If anybody is challenging this, that would be an extraordinary claim, as it would go against every single star map ever produced, and overturn centuries of successful celestial navigation. To that end some kind of proof would be needed, and not just vague statements like 'it is questioned'.

To that end, it's not clear why 'it is questioned'. It's the southern pole star - it's always there, due south, at the observer's latitude elevated above the horizon. It can be hard to see as it's quite dim, but that has nothing to do with 'only a few months of the year' - it's just quite a dim star, so you ideally need a dark sky and a telescope / binos to see it.

Moreover, whilst the focus on different continents is interesting, as it's so extreme, the problem it is highlighting is present for observers separated by only a relatively short distance in longitude, looking at the same star. On the FET monopole map, if they are both facing south (ie with their backs to North), then they will be looking in slightly different directions at the same object, which makes no sense at all.

[Tom Bishop]

You pointed out a small date and time where you think the stars will be visible simultaneously.

You then assume that you are correct that those stars can be seen simultaneously.

You then ask us to come up with a different explanation because you are going to go ahead and assume that your assumption is correct.

Do you see a flaw there?

Using Tom's answer as a starting place the wiki answer could be changed as follows:

Q. How can two people on opposite sides of the earth in Australia and South America both see the same South Pole Stars simultaneously?

A. The stars in the night sky are only visible simultaneously in these locations during a few months of the year.  In those conditions it is questioned whether it is the case that the observers actually see the same stars simultaneously.

This sounds fair enough. I support making an edit to specify this. We should give it a little more time for discussion.

[Pete Svarrior]

Seems like an innocent enough change.

[SteelyBob]

it is questioned whether it is the case that the observers actually see the same stars simultaneously.

Why is it questioned?

[JHelzer]

I don't know the correct answer for this. I am just be happy to help with improving the wiki.  I'm not looking to suggest a perfect definitive answer.  I will be very proud if even a small piece of my suggestion is implemented.

[Tom Bishop]

I have made the edit requested.

[SteelyBob]

I have made the edit requested.

From the wiki:

In those conditions it is questioned whether it is the case that the observers actually see the same stars simultaneously.

Why is it questioned? Are you suggesting that they might be looking at stars that look the same but are in fact different?