The Southern Cross, Celestial Poles, and The Shape of The Earth

[Henk001]

South of the equator when you are looking south at the southern night sky you always see the same point in the sky: the south celestial pole. Therefore the lines of sight must be parallel.
Three examples
Sydney, Australia (notice the Sydney Opera House on the left)
View attachment 26852
Image Source: http://www.rc.au.net/blog/2012/06/26/kirribilli-sydney-harbour-trails/
From Reúnion

From ESO, Chili

So, instead of this

We must assume this

 

[Mick West]

In the norther hemisphere even the most casual observer is generally familiar with at least one constellation: Ursa Major, the Great Bear, aka "The Big Dipper" in the US or "The Plough" in the UK. People are also generally familiar with Polaris, the Pole Star or North star. You might even remember that the last two stars of Ursa Major point at Polaris, and Polaris is always within a degree of true north, so quite useful for navigation.

Far fewer people in the northern hemisphere are familiar with the appearance of the skies in the Southern Hemisphere. This is a likely explanation as to why most successful flat earth promoters are in the Northern Hemisphere.

In the Southern Hemisphere there's no easy equivalent of Polaris, as the southern celestial pole (the point at which all the stars seem to rotate about) is in a region of the sky with few bright stars. There is however an equivalent of Ursa Major, the constellation known as Crux, or more commonly The Southern Cross. Crux give us a similar useful locating tool for the southern celestial pole, as the longer arms of the cross point towards the pole.

Another thing that people in the North don't often think about is that in the South the stars seem to rotate clockwise around the celestial south pole, whereas in the North they rotate counter-clockwise.

This all creates an excellent demonstration of the shape of the Earth.

Consider two places on the globe, Sydney in Australia and Santiago in Chile (any similar locations will do). Now in the southern winter the nights are long, just before sunrise in Sydney the sun has set in Santiago. If people in both places look South (i.e. away from the North Pole) at the same time, then what do they see in the sky?

Here's the view from Santiago. Crux is at the bottom.


Here's the view from Sydney, at the exact same time!



Clearly, despite looking in nearly exactly opposite direction (on a flat earth), we are actually looking at the same piece of sky. This is only possible if we are on a globe.


This is inarguable proof that the Earth is not flat, so if you ever get into an argument with someone who claims to believe in the Flat Earth (and a lot of them, of course, are just trolling), then ask them to explain this problem first to save time.

 

[Mick West]

Another way of visualizing the Southern Celestial Pole is to take Star Trail images looking South. Here's one from Chile:

Image Source: https://commons.wikimedia.org/wiki/File:All_In_A_Spin_Star_trail.jpg

And one from Australia (notice the Sydney Opera House on the left)

Image Source: http://www.rc.au.net/blog/2012/06/26/kirribilli-sydney-harbour-trails/

The centers of rotation in both images are due south. On the globe this is simply pointing towards the southern celestial pole. On a "Flat Earth" south is in totally opposite directions, yet somehow looking at the same thing.

 

[Trailspotter]

You do not need to go to the Southern hemisphere to confirm the existence of the Southern Celestial Pole. Instead, you can point a camera southwards and take a long exposure shot or night time-lapse video to visualise the star trails and see that there is the opposite centre of rotation to the Northern Celestial Pole below the horizon, so the celestial axis connecting the two poles comes through the Earth at an angle, corresponding the latitude of the observer. Such an observation that any Flat Earther can do for themselves, demonstrates that Earth is surrounded by the "Celestial Sphere" rather than covered by a Sky dome.

 

[Mick West]

You do not need to go to the Southern hemisphere to confirm the existence of the Southern Celestial Pole. Instead, you can point a camera southwards and take a long exposure shot or night time-lapse video to visualise the star trails and see that there is the opposite centre of rotation to the Northern Celestial Pole below the horizon, so the celestial axis connecting the two poles comes through the Earth at an angle, corresponding the latitude of the observer. Such and observation that any Flat Earther can do for themselves, demonstrates that Earth is surrounded by the "Celestial Sphere" rather than covered by a Sky dome.

Indeed, and you don't even need to be in the southern hemisphere to see the Southern Cross. You can see circling a point below the horizon from quite a ways north. Including Bangkok, home of Flat Earth promoter Eric Dubay.

 

[Amber Robot]

The Flat Earth Theory requires that the north and south hemispheres are radically different, and it turns out they are basically the same, just flipped.

Basically, the flat earth proponents take a single observable, like "I can't see curvature", and based on that create a model that blatantly disagrees with a hundred other observables. They never seem to attempt to look at even the simplest calculations of the predictions of their model. Sigh...

 

[Astro]

Here's a timelapse I took of the south celestial pole during a trip to South Africa last year:
The stars are definitely moving clockwise around the south celestial pole, in direct contradiction to what a flat earth would predict.

 

[dove779]

Hello and thank you for this great forum. Personally, I find the view of the stars from the southern hemisphere to be the best globe earth proof. But is there a way I can find a proof, in the form of a clear, non edited picture or a video, of the southern cross and the rest of the southern celestial pole, that has been taken from Australia, South America, and South Africa? Even better - a proof that you can watch the southern cross from South America and South Africa at the same point in time? For some reason I could not find such proofs on a simple google search.

 

[Mick West]

Even better - a proof that you can watch the southern cross from South America and South Africa at the same point in time? For some reason I could not find such proofs on a simple google search.

There's an indirect proof in that Stellarium has always been shown to match photos exactly for any given time and location. So you can just view from that location (and time) in Stellarium.

The way to falsify this would be to demonstrate Stellarium does not match reality.

A more zetetic proof is always going to rely on you trusting someone. I would suggest some kind of live stream between two flat earth believers who can stream what they see on their cameras at the same time.

Unfortunately, there's not a lot of flat earth believers in the Southern hemisphere, for obvious reason.

 

[Movie Vertigo]

You do not need to go to the Southern hemisphere to confirm the existence of the Southern Celestial Pole. Instead, you can point a camera southwards and take a long exposure shot or night time-lapse video to visualise the star trails and see that there is the opposite centre of rotation to the Northern Celestial Pole below the horizon

I did just that in my latest video. Even though I'm 52 degrees north, you can still see the stars are rotating about the south celestial pole.
There's also enough vertical field of view that you can see the celestial equator towards the top of the video, and above that a small section stars rotating about the north celestial pole.

 

[Mad Lord Snapcase]

Hello and thank you for this great forum. Personally, I find the view of the stars from the southern hemisphere to be the best globe earth proof. But is there a way I can find a proof, in the form of a clear, non edited picture or a video, of the southern cross and the rest of the southern celestial pole, that has been taken from Australia, South America, and South Africa? Even better - a proof that you can watch the southern cross from South America and South Africa at the same point in time? For some reason I could not find such proofs on a simple google search.

I took an all night time lapse looking south east from the west coast of New Zealand. It's not edited beyond placing all the individual photos in Windows Movie Maker and saving them as a video. It was my first attempt at doing this, so the quality is not great, but it's still clear enough to see the stars rotating clockwise followed by the sun rising in the east. I manually changed the exposure time on the camera as dawn approached, not in post processing.

Source: https://youtu.be/cMTg3FZNZP0

 

[Enricks]

From ESO, Chili
View attachment 17850

Just a side question: why are some trails in this pic in front of the building top?

 

[Hevach]

You can see some other ghosting around the observatory, particularly on the left side, and weird repeated shadows. Likely the observatory changed positions during the exposure.

 

[Mick West]

Here's a time lapse showing the telescope move and the circular motion of the stars
Source: https://youtu.be/xJlqe0dYFlg?t=3m24s

 

[DavidB66]

Just a word of warning on star trail time lapse photographs: some popular images on the internet, including several showing the south celestial pole with Sydney Opera House in the background, are composites. Searching Google Images for 'Sydney star trails', I would say at least half of the top twenty results are physically impossible, because the celestial pole is in the wrong place. Either it is too low in the sky, or it is not to the south of the viewpoint, or both. This one is a conspicuous example: http://www.flickriver.com/photos/wild_images/15283220928/


To be fair, the photographer describes it as 'Southern Hemisphere star trails stacked over a night image of the Sydney Opera House', so the use of the word 'stacked' might give a warning that it is a composite. I guess that any photographer wanting to take a striking image of Sydney will try to get its most familiar landmarks, the Harbour Bridge and the Opera House, in the picture somehow, even if it means throwing geography to the winds! Fortunately the picture showing star trails over the Opera House earlier in this thread does appear to be physically possible, though the photographer's blog describing his methods does imply there was a great deal of processing involved.

 

[Z.W. Wolf]

From ESO, Chili
View attachment 17850

Just a side question: why are some trails in this pic in front of the building top?

Even odder... it looks like there are interference patterns. I can't think of any reason for that.

 

[Mick West]

Even odder... it looks like there are interference patterns. I can't think of any reason for that.

Moire patterns, that's where they are strongest for Moire on concentric circles (made of square pixels). Take a pattern like this:

You can probably see the patterns just on the screen, especially as you scroll the image, but if you resample it, it's more apparent as a still image:

 

[edby]

From p.23 of Zetetic Astronomy by 'Lady Blount' and Albert Smith. This explains how the southern stars appear to rotate clockwise around a southern axis, while the northern stars appear to rotate anticlockwise around a northern axis, rather like two gear wheels rotating in opposition.

Note that unlike pre-Copernican astronomy, where the celestial sphere is a sphere, in Zetetic Astronomy they move in a plane. The sun spirals round from a northern orbit (in London summer) to a southern one (in Sydney summer).

Only one problem I think. A star in the southern hemisphere which is close to a star in the northern hemisphere where the gears come into contact will appear to move away as the gears rotate. But we don't in fact see this when we stand on the equator. All the stars appear to have fixed position with respect to each other. Nor do we see any blank space in the parts, e.g. ACF where they are diverging.

Interesting theory though.

 

[Mick West]

All the stars appear to have fixed position with respect to each other.

That's the key. It's very hard to convey though. The notion of something that looks like an infinitely distant celestial sphere is just something that the mind rejects. The problem is you can't draw a diagram because of the scale.

This video shows a typical representation, utterly unlike reality, which confuses people.
Source: https://www.youtube.com/watch?v=1Toya19H12w

 

[edby]

Does it confuse people? I find it perfectly natural to think of it as a sphere, rotating around the earth.

It's imagining it as a flat plane that I find difficult, indeed impossible.

My natural model, conforming to senses is: flat earth, spherical heavens.

However the Zetetic movement was born at a time when people knew about different 24 hr time zones. That is inconsistent in a model where everyone lives on the top of the flat earth, and the sun would be invisible to everyone at the same time.

 

[Mick West]

Does it confuse people? I find it perfectly natural to think of it as a sphere, rotating around the earth.

I confuses people because the stars are actually trillions of miles away scattered through the universe like specks of dust — then they see a diagram where the stars are about 20,000 miles away fixed on a semi-transparent sphere.

It's a very useful way to thinking about the night sky, but A) it's not like that, and B) the constellations would change size if it was that close (smaller at the horizon) — so you've got to also note it's trillions of miles away, despite the diagram.

Once you get it, then it's natural. But if you're starting out thinking the Earth it flat, then you will have problems. It's an abstraction with problems, so accepting that then lets them accept other abstractions, like intermeshed cogs and atmospheric lensing.

 

[edby]

Ah right. Indeed, but the Ptolemaic system doesn't make any such assumptions about the vast distance of stars.

Stellar parallax wasn't observable until 1838, I think. https://en.wikipedia.org/wiki/Stellar_parallax, from which the true distance of stars can be worked out.

 

[edby]

[edit] Here we are

In 1838 Bessel won the race, announcing that 61 Cygni had a parallax of 0.314 arcseconds; which, given the diameter of the Earth's orbit, indicated that the star is 10.3 ly away.[7][8][9] Given the current measurement of 11.4 ly, Bessel's figure had an error of 9.6%. https://en.wikipedia.org/wiki/Friedrich_Bessel

 

[Mick West]

Ah right. Indeed, but the Ptolemaic system doesn't make any such assumptions about the vast distance of stars.

Well, it would have to have a fairly large distance, otherwise the constellations would be measurably smaller near the horizon.

And talking about Ptolemaic, it might confuse everyone if you are explaining why the Earth is not flat by showing how things work better in a geocentric spherical model, when really they know you at least think it's heliocentric.

 

[edby]

Right, but the guiding principle of Zetetic theory is to prefer an explanation where things are actually the way they appear to be. If you look at YouTube, the most common comment is 'I know what it looks like, and it looks like it's flat', 'water can't be curved' etc.

However there is a problem when we extend this to the heavens. Pre-theoretically, it looks like a large sphere with the stars and moon at some large, but not incredibly large, distance from us. And that works fine until we find out about time zones, which we didn't know about in ancient days. So there is a conflict between 3 perfectly natural ideas (1) earth appears flat (2) heavens look like a rotating sphere (3) you can call people up on the, er, other side of the world and it is day time, whereas it is night where you are.

One of these has to give. For Flat earthers, it's (2). The stars are on a flat plane.

Hope that makes more sense.

 

[Z.W. Wolf]

Does it confuse people? I find it perfectly natural to think of it as a sphere, rotating around the earth.

It confuses people who:
-struggle with expanding a concept
-have difficulty dealing with metaphors and analogies
-are overly-literal
-have poor spatial reasoning

Especially a group that is aggressive, engages in motivated thinking and rationalization, and unconsciously places themselves in a mode of thought that exaggerates all the four above problems.

 

[Z.W. Wolf]

I've made some changes.

...the guiding principle of Zetetic theory is to prefer an explanation where things are actually the way they appear to be. If you look at YouTube, the most common comment is 'I know what it looks like, and it looks like it's flat', 'water can't be curved' etc.

However there is a problem when we extend this to the heavens. Pre-theoretically, it looks like a large sphere dome with the stars and moon at some large, but not incredibly large, distance from us.

And that works fine until we find out about time zones, which we didn't know about in ancient days. So there is a conflict between 3 2 perfectly natural ideas (1) earth appears flat (2) heavens look like a rotating sphere dome.[Intuitive]

[Analytical] (3) you can call people up on the, er, other side of the world and it is day time, whereas it is night where you are.

One of these has to give. For Flat earthers, it's (2) (3) [because this involves more than one mental step, and it is more amenable to rationalization].

 

[Z.W. Wolf]

Ah right. Indeed, but the Ptolemaic system doesn't make any such assumptions about the vast distance of stars.

Stellar parallax wasn't observable until 1838, I think. https://en.wikipedia.org/wiki/Stellar_parallax, from which the true distance of stars can be worked out.

There were steps between the Ptolemaic model and the modern heliocentric model.

-The Copernican heliocentric model placed all 5 known planets in circular orbits around the sun while retaining epicycles and deferents. [Still quite flawed.]
-The rival Tychonic system placed the earth at the center, with the sun and moon orbiting the earth and all 5 known planets orbiting the sun. The inferior planets were in small orbits that never circled the earth and the superior planets were in large orbits that did circle the earth but were not orbiting the earth. Retrograde motion was explained with no need for epicycles and deferents. Interesting.

Both retained the celestial sphere model.

Wikipedia

The Copernican explanation for the lack of parallax was that the stars were such a great distance from Earth that Earth's orbit was almost insignificant by comparison. However, Tycho noted that this explanation introduced another problem: Stars as seen by the naked eye appear small, but of some size, with more prominent stars such as Vega appearing larger than lesser stars such as Polaris, which in turn appear larger than many others. Tycho had determined that a typical star measured approximately a minute of arc in size, with more prominent ones being two or three times as large.

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Astronomers in Tycho's time were doing naked eye observation, they didn't fully grasp atmospheric effects, or know much about optics of the human eye or optics in general. They swore they could see stars with shapes and sizes. (Many people still do and will draw stars confused as UFO's with complicated shapes.)

Tycho used basic geometry to show that, assuming a small parallax that just escaped detection, the distance to the stars in the Copernican system would have to be 700 times greater than the distance from the sun to Saturn. Moreover, the only way the stars could be so distant and still appear the sizes they do in the sky would be if even average stars were gigantic—at least as big as the orbit of the Earth, and of course vastly larger than the sun. (As a matter of fact, most stars visible to the naked eye are giants, supergiants, or large, bright main-sequence stars.) And, Tycho said, the more prominent stars would have to be even larger still. And what if the parallax was even smaller than anyone thought, so the stars were yet more distant? Then they would all have to be even larger still.[11] Tycho said

Deduce these things geometrically if you like, and you will see how many absurdities (not to mention others) accompany this assumption [of the motion of the earth] by inference.[12]

Copernicans offered a religious response to Tycho's geometry: titanic, distant stars might seem unreasonable, but they were not, for the Creator could make his creations that large if he wanted.[13] In fact, Rothmann responded to this argument of Tycho's by saying

[W]hat is so absurd about [an average star] having size equal to the whole [orbit of the Earth]? What of this is contrary to divine will, or is impossible by divine Nature, or is inadmissible by infinite Nature? These things must be entirely demonstrated by you, if you will wish to infer from here anything of the absurd. These things that vulgar sorts see as absurd at first glance are not easily charged with absurdity, for in fact divine Sapience and Majesty is far greater than they understand. Grant the vastness of the Universe and the sizes of the stars to be as great as you like—these will still bear no proportion to the infinite Creator. It reckons that the greater the king, so much greater and larger the palace befitting his majesty. So how great a palace do you reckon is fitting to GOD?

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-Kepler refined the Copernican system with his first and second laws of planetary motion:The Law of Ellipses and The Equal-Areas Law.

The Tychonic system hung on for awhile in the 17th century but faded. I don't think there were many astronomers who believed in it much past 1650.

In the late 17th century, a number of physical astronomy theories drawing from Kepler's work—notably those of Giovanni Alfonso Borelli and Robert Hooke—began to incorporate attractive forces (though not the quasi-spiritual motive species postulated by Kepler) and the Cartesian concept of inertia.[87] This culminated in Isaac Newton's Principia Mathematica (1687), in which Newton derived Kepler's laws of planetary motion from a force-based theory of universal gravitation.[88]

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By then the Tychonic system was a quaint footnote. Did anyone still find it relevant? I don't know. The last nail (if it was needed) wasn't the measurement of parallax in 1838. It was the discovery of stellar aberration in 1727 by James Bradley while he was searching for evidence of stellar parallax. By that time mainstream astronomy assumed parallax would someday be found with better instruments.

 

[edby]

I've made some changes.

...the guiding principle of Zetetic theory is to prefer an explanation where things are actually the way they appear to be. If you look at YouTube, the most common comment is 'I know what it looks like, and it looks like it's flat', 'water can't be curved' etc.

However there is a problem when we extend this to the heavens. Pre-theoretically, it looks like a large sphere dome with the stars and moon at some large, but not incredibly large, distance from us.

And that works fine until we find out about time zones, which we didn't know about in ancient days. So there is a conflict between 3 2 perfectly natural ideas (1) earth appears flat (2) heavens look like a rotating sphere dome.[Intuitive]

[Analytical] (3) you can call people up on the, er, other side of the world and it is day time, whereas it is night where you are.

One of these has to give. For Flat earthers, it's (2) (3) [because this involves more than one mental step, and it is more amenable to rationalization].

Not sure. I agree at any point in time it looks like a dome, i.e. a hemispherical object. But a rotating dome? What happens at the next point in time when stars have risen in the East? Have we annihilated the ones that set in the West, then created a new set of stars that have ‘risen’? That seems counterintuitive. When we see the top part of a person’s body above a hedge, do we assume intuitively that only the top part exists? Do we intuit that a person facing us has no back, and that when he turns away from us his front is destroyed and a new back part created?


Regarding (3), the time zones, I agree this is not intuition. Yet we have to explain somehow why Zetetic astronomy moved from the intuitive idea of a celestial dome/sphere, to that of a disc.

 

[Z.W. Wolf]

The Egyptians and Mesopotamians thought the sky was a fixed dome, not a rotating one. The heavenly bodies were in the fabric or body of the dome but their motion did not come from the motion of the dome. They moved about inside it. The sun and moon traveled over the earth and then under it or through a tunnel in its lower depths. Thus sunsets had a more logical cause than modern flat earth theory. In this model the earth would enter night at the same time everywhere. Later the Greeks postulated that this was not true, but they had no way to prove it.

 

[edby]

Surely the idea of a tunnel implies a sphere rather than a hemisphere? Or did they think the tunnel was completely flat or straight? How do we know they believed this?

 

[edby]

However a check on A History of Ancient Mathematical Astronomy By O. Neugebauer p.577 suggests you are right.

Interesting.

 

[Z.W. Wolf]

The Egyptians and Mesopotamians were much more concentrated on the religious and prophetic meaning of astronomy and less on cosmology. We're talking about a very long history and there is no one completely standard model, but very generally the Mesopotamians believed that the flat world was afloat in an infinite ocean; not on the surface, but in the midst. There were waters above the dome of the sky as well. This belief was shared by the Hebrews and scraps of this flat earth cosmology show up in the Old Testament.

The Egyptians believed the earth is flat and oval with a vast Underworld with different levels, gates, and passages. Ra, the sun god, had to make a difficult journey through the Underworld each night. He entered in the west and emerged, reborn, in the east. This cosmology makes some sense if you stay at home and don't travel about. I've never seen an explanation for setting and rising stars, but it makes sense that they too dipped below and rose above the edge after an Underworld journey. I don't know if the Egyptians felt it necessary to even think about that. I do know that they had a special reverence for the circumpolar stars which never set, either during a complete day or the year. They were eternal.

Later, the Greeks had a different, analytical, mindset and were interested in the physical nature of the universe in its own right. Through analysis, and an awareness of what the sky looks like from different parts of the earth, they found evidence for a spherical earth, inside a celestial sphere.

I'll let Aristotle speak for himself:

"Again, our observations of the stars make it evident, not only that the earth is circular [spherical], but also that it is a circle [sphere] of no great size. For quite a small change of position to south or north causes a manifest alteration of [what is visible in the sky at] the horizon. There is much change, I mean, in the stars which are overhead [in the sky], and the stars seen are different, as one moves northward or southward. Indeed there are some stars [e.g.Canopus] seen in Egypt and in the neighborhood of Cyprus which are not seen in the northerly regions; and [circumpolar] stars, which in the north are never beyond the range of observation, in those regions [Egypt] rise and set. All of which goes to show not only that the earth is circular [spherical] in shape, but also that it is a sphere of no great size: for otherwise the effect of so slight a change of place would not be quickly apparent."

Simple geometry; which should be intuitively obvious.

Aristotle was just one of many. He was speaking of a standard model that was emerging. One of the arguments for this model was that if the earth were flat, the entire earth would enter night at the same time. They believed it didn't. But this was circular logic, because they had no empirical evidence for "time zones." They weren't perfect.

In the Egyptian model the sunset intuitively looks "right." The sun is falling below an edge. The 19th century Zetetics couldn't ignore time zones and had to modify the more logical Egyptian model, and posited a sun making a circle above the the FE. This makes no analytical sense, but neither does it make intuitive sense. That's not what the sun looks like it's doing. It's an example of how the modern Flat Earthers have to concoct elaborate theories that violate their own philosophy of trust your own eyes.

At first, 21st century FE Believers simply ignored the two celestial poles; (mostly because they didn't know about them). Now they can't. They are now engaged in concocting more and more elaborate theories to explain the two celestial poles. Some of them involve refraction through the dome, some with reflections in the dome of two counter-rotating disks, others more mystical, and some that rely on simple confusion. The modern heliocentric model is much more intuitive, it looks as if we are inside a celestial sphere. The FE Believers are once again violating their own philosophy.

 

[edby]

Thanks for this, v helpful. Incidentally, slightly off topic, but do you have a sense of when people started thinking that stars were really a very long way away? I read that Herschel suggested this about the Milky Way, but couldn't find a reference.

 

[Trailblazer]

Thanks for this, v helpful. Incidentally, slightly off topic, but do you have a sense of when people started thinking that stars were really a very long way away? I read that Herschel suggested this about the Milky Way, but couldn't find a reference.

Tyco Brahe used parallax measurements in 1577 to show that a comet was further away than the moon. He also tried and failed to observe parallax with the stars, so concluded that either the Earth was motionless at the centre of the universe, or the stars were a really really long way away.

He chose the wrong option, unfortunately.

 

[Mick West]

Thanks for this, v helpful. Incidentally, slightly off topic, but do you have a sense of when people started thinking that stars were really a very long way away? I read that Herschel suggested this about the Milky Way, but couldn't find a reference.

It's kind of a necessary conclusion from heliocentrism, given the very large orbit of the Earth. One of the earliest heliocentrists was Aristarchus of Samos (b 310 BC) . Wikipedia says of him:

Aristarchus suspected the stars were other suns that are very far away, and that in consequence there was no observable parallax, that is, a movement of the stars relative to each other as the Earth moves around the Sun. Since stellar parallax is only detectable with telescopes, his accurate speculation was unprovable at the time.

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[edby]

This book looks good.

In the dramatic tradition of the best selling "Longitude", this book charts the historical path of observational astronomy's most daunting challenge: measuring the distance to a star. The greatest scientific minds applied themselves in vain to the problem across the millennia, beginning with the ancient Greeks. Not until the 19th century would three astronomers, armed with the best telescopes of the age, race to conquer this astronomical Everest, their contest ending in a virtual dead heat. Against a backdrop filled with kidnappings, dramatic rescue, swordplay, madness, and bitter rivalry, the author brings to life the heroes of this story. A destitute boy plucked from a collapsed building becomes the greatest telescope maker the world has ever seen, a hot tempered Dane's nose is lopped off in a duel over mathematics, a merchant's apprentice is forced to choose between the lure of money and his passion for astronomy, and a musician astounds the world by discovering a new planet from his own backyard. https://www.amazon.co.uk/Parallax-Measure-Alan-W-Hirshfeld/dp/0716737116

 

[Mick West]

Archimedes wrote:
https://en.wikipedia.org/wiki/The_Sand_Reckoner

His [Aristarchus'] hypotheses are that the fixed stars and the Sun remain unmoved, that the Earth revolves about the Sun on the circumference of a circle, the Sun lying in the middle of the orbit, and that the sphere of fixed stars, situated about the same center as the Sun, is so great that the circle in which he supposes the Earth to revolve bears such a proportion to the distance of the fixed stars as the center of the sphere bears to its surface.[4]

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That seems to suggest that the stars are at 2 AU (1 AU = distance from sun to earth), which it would seem to be obviously incorrect even back then, so maybe I'm misreading it?

Ah, later it is clarified:

Archimedes then concluded that the diameter of the Universe was no more than 1014 stadia (in modern units, about 2 light years),

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[Dan Ly]

This book looks good.

I own a copy of this book and would highly recommend it. It's a fascinating tale detailing the working of many astronomers who toiled over centuries trying to find stellar parallax. It basically became the equivalent of the space race. If I recall correctly, it was actually Thomas Henderson who first successfully detected stellar parallax from observations of Alpha Centauri but he was cautious to publish because of a number of false positives from work by others. In the end it is Friedrich Bessel who gets the credit because he published first! Anyway, I don't want to get too off topic I just recommend reading this book

 

[edby]

I own a copy of this book and would highly recommend it. It's a fascinating tale detailing the working of many astronomers who toiled over centuries trying to find stellar parallax. It basically became the equivalent of the space race. If I recall correctly, it was actually Thomas Henderson who first successfully detected stellar parallax from observations of Alpha Centauri but he was cautious to publish because of a number of false positives from work by others. In the end it is Friedrich Bessel who gets the credit because he published first! Anyway, I don't want to get too off topic I just recommend reading this book

Thanks, and just as well you posted that as I had already ordered it from Amazon.

It's kind of on-topic as it relates to the question of what the celestial sphere looks like. It doesn't look as though all the stars are different distances. Yet they are, or at least that's what 'science' says.