Offline Xfires

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Re: Anyone for a public discussion?
« Reply #20 on: November 13, 2017, 03:17:49 AM »

The whole paper is about creating a simple 3D model of rotating bodies and then concluding that because a simulation can be made of moving bodies, that the n-body problem has been solved.

At no point do they actually come up with a solution to the three body problem. They think that they can create a 3D model of moving bodies, run it a few times, see the pattern and therefore they can predict future occurrences from the pattern and the three body problem has been solved.

This is like saying that you solved the 3 body problem because you went online to one of those comet gravity simulators and tossed some balls around to rotate around each other, traced out where they were moving and that you therefore solved the 3 body problem.

It is not the same at all. In your example, you are finding a pattern where there is none, whereas, in the 3 body problem, they have run the simulations so many times that they can see the same pattern repeat itself so many times that they can formulate a guess that it is accurate to a close enough margin that it doesn't really matter   

Offline mtnman

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Re: Anyone for a public discussion?
« Reply #21 on: November 13, 2017, 03:51:06 AM »

This is like saying that you solved the 3 body problem because you went online to one of those comet gravity simulators and tossed some balls around to rotate around each other, traced out where they were moving, and that you therefore solved the 3 body problem. It is not a solution. You found a pattern in your gravity simulator. It is not useful for solving problems.
3 body problem, eclipses, etc.

Isn't this where Junker or someone usually criticizes posts for being off topic and derailing threads?

Tom, are you accepting or declining his invitation?

« Last Edit: November 13, 2017, 03:30:15 PM by mtnman »

Re: Anyone for a public discussion?
« Reply #22 on: November 13, 2017, 05:36:25 AM »
Hmm, interesting storm of responses.

I'll reply here to Tom Bishop's assertion that modern astronomy predicts occultations by using patterns derived from previous observations. This goes to the heart of how science works.

Indeed, science always starts from observed patterns; then people produce models to understand those patterns, and eventually laws to systematize them. The relevant example here is Kepler's Laws of Planetary Motion, which then led to Newton's Theory of Universal Gravitation. Modern astronomy uses gravitational theory (Newtonian or Einsteinian, depending on the accuracy needed) to calculate the motion of the moon in its orbit about the earth and the planets in their orbits about the sun. Patterns tell us that occultations of Aldebaran by the moon occur regularly, but theory predicts that a particular occultation can be observed at a particular site at a time specified to within a tenth of a second. Observations feed back into the theory, giving us ever better predictive capability.

This is what I ask from a flat-earth theorist. Not patterns, but precise predictions.

That modern astronomy no longer relies on mere patterns to predict occultations is shown by the fact that we can predict occultations of stars by newly discovered asteroids. The popular astronomy magazine Sky and Telescope regularly publishes such predictions to encourage backyard astronomers to look for them.

And since the theme of the three-body problem has crept into this discussion, I should remark that ephemeris calculations of newly discovered asteroids (or of any other solar system object) are routinely done by numerical integration of the equations of motion of that body in the gravitational field produced by the sun, all the planets, and the several largest asteroids. This is not an impossible problem; it is solved thousands of times daily.

Re: Anyone for a public discussion?
« Reply #23 on: November 13, 2017, 05:46:36 AM »
At no point do they actually come up with a solution to the three body problem. They think that they can create a 3D model of moving bodies, run it a few times, see the pattern, and therefore they can predict future occurrences from the pattern and the three body problem has been solved.

you're severely misunderstanding two things: 1) what the paper is saying, and 2) what an analytic solution means.

first, the paper is not describing patter recognition.  the parts you're describing are meant to demonstrate that the code does what it's supposed to do by asking it to find numerical solutions to problems for which there are known analytic solutions.  the author starts by demonstrating that it correctly solves two-body problems.  then he shows that it correctly solves a special case of the three-body problem.  and so on.

second, you're conflating "does not have an analytic solution" with "cannot be solved."  that's not what it means, though.  here's an example:

suppose you make a graph of an object's position over time and you get a graph like this.  there's a function that will tell you the value of the graph at any arbitrary point along the horizontal axis.  this "motion" has an anlytical solution.  it can be described by functions we know.


now suppose you see this graph.  there is no function that will tell you the value of the graph at any arbitrary point along the horizontal axis.  it's just a bunch of random chaotic movement.  it's hardly a failure of physics that mathematics does not have analytic functions to describe a graph like this.


the only reason two-body problems can be solved analytically is that it's circular/elliptical motion, and we have lots of functions for that.  if two-body motion were like the second graph, then we wouldn't have analytic solutions for them, either.  it's not a coincidence that the special cases for which there are analytic solutions to the three-body problem all involve circular motion.

ironically, these simulations are exactly about using geometry and physics to solve a problem that has no purely mathematical solution.
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Offline Tom Bishop

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Re: Anyone for a public discussion?
« Reply #24 on: November 13, 2017, 06:35:36 AM »
Quote from: retiredAstrophysicist
Indeed, science always starts from observed patterns; then people produce models to understand those patterns, and eventually laws to systematize them. The relevant example here is Kepler's Laws of Planetary Motion, which then led to Newton's Theory of Universal Gravitation. Modern astronomy uses gravitational theory (Newtonian or Einsteinian, depending on the accuracy needed) to calculate the motion of the moon in its orbit about the earth and the planets in their orbits about the sun.

Except that NASA still uses the Saros Cycle for its Lunar Eclipse and Solar Eclipse predictions, which is an ancient pattern-based method for finding the time of the eclipse. They are not using a geometric model.

Go to NASA's Eclipse Website -> Resources -> Eclipses and the Saros

That is the only method given on that entire website. They do not describe "motion laws" and "gravitational theory". They describe a method used by an ancient society of people who believed that the earth was flat.

It is mentioned on the NASA site that the Solar Ecliple may also be predicted with Besselian Elements, but we can see from this description of the method on stackexchange (at the bottom) that it is just another pattern-based method.

Quote
That modern astronomy no longer relies on mere patterns to predict occultations is shown by the fact that we can predict occultations of stars by newly discovered asteroids. The popular astronomy magazine Sky and Telescope regularly publishes such predictions to encourage backyard astronomers to look for them.

Why are you lying to us?

Go here to find how Sky and Telescope makes such predictions of the occultations of stars by asteroids: http://www.skyandtelescope.com/observing/planetary-occultation-highlights-for-2002/

Do you see any equations on that page? Do you see any assumptions of the distances to stars or asteroids?

They are making a map of the path stars travel over the surface of the earth (they don't move much, unlike the moon) and determining where the path of the astroid will intersect. This is absoutely a method that relies on patterns. They are determining what the pattern of the stars over the earth are, and determining whether the asteroids will intersect that path. This is pattern based. There are no geometric equations or any real Round Earth Theory assumptions.

Quote
This is what I ask from a flat-earth theorist. Not patterns, but precise predictions.

I don't see why we need to give any predictions more than the pattern based method which already exist. Sky and Telescope tells us that this can all be predicted without needing to know much about the Round Earth model.

Quote
And since the theme of the three-body problem has crept into this discussion, I should remark that ephemeris calculations of newly discovered asteroids (or of any other solar system object) are routinely done by numerical integration of the equations of motion of that body in the gravitational field produced by the sun, all the planets, and the several largest asteroids. This is not an impossible problem; it is solved thousands of times daily.

You will have to show that any such geometric models are accurate.

NASA certainly isn't using a three body problem to give us its eclipse predictions. Sky and Telescope is not using complex gravitational equations for their asteroid occultations predictions.

Are we to believe in this assertion without evidence?
« Last Edit: November 13, 2017, 06:58:21 AM by Tom Bishop »

Re: Anyone for a public discussion?
« Reply #25 on: November 13, 2017, 06:53:24 AM »
First, NASA does use a special solve of the three body problem for eclipses. If you haven't managed to piece that together after last time I'm not bothering to go over it again.

Second, as I pointed out last time, not insignificant evidence has been found pointing to the astronomers of the time period of the Saros Cycles creation, believed in a round Earth. I presented this last time you brought this up as well, so I don't expect it to sick this time either. I'll dig things up when I'm not on mobile, but a heliocentric globe model was found.

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Offline Tom Bishop

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Re: Anyone for a public discussion?
« Reply #26 on: November 13, 2017, 07:06:48 AM »
you're severely misunderstanding two things: 1) what the paper is saying, and 2) what an analytic solution means.

first, the paper is not describing patter recognition.  the parts you're describing are meant to demonstrate that the code does what it's supposed to do by asking it to find numerical solutions to problems for which there are known analytic solutions.  the author starts by demonstrating that it correctly solves two-body problems.  then he shows that it correctly solves a special case of the three-body problem.  and so on.

second, you're conflating "does not have an analytic solution" with "cannot be solved."  that's not what it means, though.  here's an example:

suppose you make a graph of an object's position over time and you get a graph like this.  there's a function that will tell you the value of the graph at any arbitrary point along the horizontal axis.  this "motion" has an anlytical solution.  it can be described by functions we know.


now suppose you see this graph.  there is no function that will tell you the value of the graph at any arbitrary point along the horizontal axis.  it's just a bunch of random chaotic movement.  it's hardly a failure of physics that mathematics does not have analytic functions to describe a graph like this.


the only reason two-body problems can be solved analytically is that it's circular/elliptical motion, and we have lots of functions for that.  if two-body motion were like the second graph, then we wouldn't have analytic solutions for them, either.  it's not a coincidence that the special cases for which there are analytic solutions to the three-body problem all involve circular motion.

ironically, these simulations are exactly about using geometry and physics to solve a problem that has no purely mathematical solution.

Gary, what are you talking about?

In the article you linked the authors basically created a scenerio where three bodies moved around each other and decided that they solved the three body problem. When you make a graph with a function you are computing a pattern.

Solving the three body problem is actually much more complicated than that; it's providing a solution that will allow us to solve the problems in space and physics, where we do not know the exact "function" that brings the scenerio to its conclusion. You admitted yourself that the solution of the page was not very useful.
« Last Edit: November 13, 2017, 07:10:07 AM by Tom Bishop »

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Offline Tom Bishop

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Re: Anyone for a public discussion?
« Reply #27 on: November 13, 2017, 08:34:22 AM »
First, NASA does use a special solve of the three body problem for eclipses. If you haven't managed to piece that together after last time I'm not bothering to go over it again.

A simple link will suffice. I have been all over that website and have found no such thing.

Quote
Second, as I pointed out last time, not insignificant evidence has been found pointing to the astronomers of the time period of the Saros Cycles creation, believed in a round Earth. I presented this last time you brought this up as well, so I don't expect it to sick this time either. I'll dig things up when I'm not on mobile, but a heliocentric globe model was found.

Here was your post:

What I stated is all laid out right here and I'm not speaking about Babylonia as a whole, but the astronomers and astrologers of the time. Even in Greece the idea of a round Earth was (at least early on) largely a view among the higher educated populace. At least based on what I've read while looking into this.

Under your Babylonian Astronomy section you linked us to as your evidence there is no mention of Round Earth anywhere. Do a search for "round" on that page. We do see the word Heliocentric, however (and that Wiki section says it was just one guy who supported Heliocentricism, FYI). You asserted that because they believed that the planetary model was Heliocentric, that this must also be a Round Earth model.

You are incorrect on all points. The word "round" or "sphere" does not appear on the Babylonian Astronomy page on the page you linked us to in reference to the earth's shape, and Heliocentric merely means sun at the center.

Under our current Flat Earth model, in fact, the planetary model is also Heliocentric. The sun is the center of our solar system. The Babylonians were smart enough to figure that out that the earth is flat and that the planetary model is Heliocentric. They were truly ahead of their time.

Rama Set

Re: Anyone for a public discussion?
« Reply #28 on: November 13, 2017, 01:04:18 PM »
Tom, the Saros cycle as it was used 1,000s of years ago is not sufficient to predict eclipses worldwide. You also have to perform a transformatiom of the coordinates based on, what kind of earth shape? Anyone? Anyone? Yes, a round earth.

Re: Anyone for a public discussion?
« Reply #29 on: November 13, 2017, 01:28:39 PM »
Is Babylon the center of the world and weren't there mythological objects on the babylonian map.
« Last Edit: November 13, 2017, 01:31:22 PM by 332e3134 »

Rama Set

Re: Anyone for a public discussion?
« Reply #30 on: November 13, 2017, 01:59:40 PM »
Is Babylon the center of the world and weren't there mythological objects on the babylonian map.

Irrelevant.  The Saros cycle was and is a very good way to predict eclipses. 

Offline StinkyOne

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Re: Anyone for a public discussion?
« Reply #31 on: November 13, 2017, 02:20:37 PM »
Why are you lying to us?

Go here to find how Sky and Telescope makes such predictions of the occultations of stars by asteroids: http://www.skyandtelescope.com/observing/planetary-occultation-highlights-for-2002/

Do you see any equations on that page? Do you see any assumptions of the distances to stars or asteroids?

They are making a map of the path stars travel over the surface of the earth (they don't move much, unlike the moon) and determining where the path of the asteroid will intersect. This is absolutely a method that relies on patterns. They are determining what the pattern of the stars over the earth are, and determining whether the asteroids will intersect that path. This is pattern based. There are no geometric equations or any real Round Earth Theory assumptions.

For the ease of argument, let's say this is all pattern-based. In what way does that disprove a round Earth? You use this pattern thing as a strawman to attack astronomy as a whole, but you really haven't thought it through. Here is your problem - even if everything in the sky is based on a repeating pattern, the ability to accurately tell you when and where something is going to occur requires a map that is highly accurate. Can FET make similar predictions over a large area? Can FET make any predictions at all?

Sky and Telescope magazine is for a lay audience. They are not going to include equations... smh
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Re: Anyone for a public discussion?
« Reply #32 on: November 13, 2017, 02:42:11 PM »
First, NASA does use a special solve of the three body problem for eclipses. If you haven't managed to piece that together after last time I'm not bothering to go over it again.

A simple link will suffice. I have been all over that website and have found no such thing.
https://eclipse.gsfc.nasa.gov/SEpubs/5MCSE.html
Not sure how you've missed these considering they're the references on the bottom of the eclipse website. Please direct your attention to the 'Predictions' section of the page.

Quote
Second, as I pointed out last time, not insignificant evidence has been found pointing to the astronomers of the time period of the Saros Cycles creation, believed in a round Earth. I presented this last time you brought this up as well, so I don't expect it to sick this time either. I'll dig things up when I'm not on mobile, but a heliocentric globe model was found.

Here was your post:

What I stated is all laid out right here and I'm not speaking about Babylonia as a whole, but the astronomers and astrologers of the time. Even in Greece the idea of a round Earth was (at least early on) largely a view among the higher educated populace. At least based on what I've read while looking into this.

Under your Babylonian Astronomy section you linked us to as your evidence there is no mention of Round Earth anywhere. Do a search for "round" on that page. We do see the word Heliocentric, however (and that Wiki section says it was just one guy who supported Heliocentricism, FYI). You asserted that because they believed that the planetary model was Heliocentric, that this must also be a Round Earth model.

You are incorrect on all points. The word "round" or "sphere" does not appear on the Babylonian Astronomy page on the page you linked us to in reference to the earth's shape, and Heliocentric merely means sun at the center.

Under our current Flat Earth model, in fact, the planetary model is also Heliocentric. The sun is the center of our solar system. The Babylonians were smart enough to figure that out that the earth is flat and that the planetary model is Heliocentric. They were truly ahead of their time.
Yes you would need to actually follow the link to https://en.wikipedia.org/wiki/Seleucus_of_Seleucia where it's explained what his model was. Considering he has the Earth rotating about it's own axis, I have my doubts it was a flat Earth in use. As for the other scholars mentioned, neither system discussed makes reference to globe/flat (I personally feel if it was flat it would be noted though) so we have 25% of noted figures of that period holding to a round Earth.

I would argue on yours being 'Heliocentric' as it's more a bastardization of Geocentric and Heliocentric and not quite either, but that's neither here nor there.

Re: Anyone for a public discussion?
« Reply #33 on: November 13, 2017, 02:51:05 PM »
Is Babylon the center of the world and weren't there mythological objects on the babylonian map.

Irrelevant.  The Saros cycle was and is a very good way to predict eclipses.

Does it not contradict then being ahead of their time? Your response is more of a deflection from that; I see that a lot on here.

I don't really intend to post much on here, I was just curious.

Offline mtnman

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Re: Anyone for a public discussion?
« Reply #34 on: November 13, 2017, 03:31:13 PM »

This is like saying that you solved the 3 body problem because you went online to one of those comet gravity simulators and tossed some balls around to rotate around each other, traced out where they were moving, and that you therefore solved the 3 body problem. It is not a solution. You found a pattern in your gravity simulator. It is not useful for solving problems.
3 body problem, eclipses, etc.

Isn't this where Junker or someone usually criticizes posts for being off topic and derailing threads?

Tom, are you accepting or declining his invitation?


Re: Anyone for a public discussion?
« Reply #35 on: November 13, 2017, 04:32:43 PM »
imagine you bring a pebble inside and drop it from some height.  you make a plot of its position over time (its lateral motion, let's say) and you get a straight line.  neat!  there is a mathematical function that describes straight lines.  you have an analytic solution for the object's position with respect to time or displacement or something.

now imagine you bring a leaf inside and drop it from some height.  you plot its position over time, but now the plot is all messy, like graph #2 from my previous post.  damn.  there is no analytic solution that describes this motion.

where did the failure of physics happen?  you didn't do any physics.  you just plotted the position of an object over time.  one of them happened to be describable by well-known analytic functions.  the other did not.  nothing failed at anything.  it's just that lots of stuff can't be described analytically.

now imagine that i have a phd in fluid dynamics or something, and i simulate your leaf-dropping in a computer.  i tell it how to update the position of the leaf over time using equations of motion from physics.  if my code makes correct predictions, then it's asinine to say "your solution isn't analytical therefore it's wrong and/or meaningless."  the opposite is true.  i've used the laws of physics to get a numerical solution to an analytically unsolvable problem.  that's a success, not a failure.

In the article you linked the authors basically created a scenerio where three bodies moved around each other and decided that they solved the three body problem. When you make a graph with a function you are computing a pattern.

Solving the three body problem is actually much more complicated than that; it's providing a solution that will allow us to solve the problems in space and physics, where we do not know the exact "function" that brings the scenerio to its conclusion. You admitted yourself that the solution of the page was not very useful.

you are completely misunderstanding both what this paper is saying, and what an analytic solution represents.  and what a function is, if i'm being completely honest.

also i did not say that the solution from that paper is not very useful.  i said that there do exist analytic solutions to 3bp, but they are not useful.  numerical solutions are useful and make accurate predictions.  numerical solutions are computationally expensive (you're iterating lots of tiny time-steps, for example), but they're not less useful/accurate/valuable than analytic solutions.

« Last Edit: November 13, 2017, 04:35:33 PM by garygreen »
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Offline TomInAustin

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Re: Anyone for a public discussion?
« Reply #36 on: November 13, 2017, 07:36:19 PM »
imagine you bring a pebble inside and drop it from some height.  you make a plot of its position over time (its lateral motion, let's say) and you get a straight line.  neat!  there is a mathematical function that describes straight lines.  you have an analytic solution for the object's position with respect to time or displacement or something.

now imagine you bring a leaf inside and drop it from some height.  you plot its position over time, but now the plot is all messy, like graph #2 from my previous post.  damn.  there is no analytic solution that describes this motion.

where did the failure of physics happen?  you didn't do any physics.  you just plotted the position of an object over time.  one of them happened to be describable by well-known analytic functions.  the other did not.  nothing failed at anything.  it's just that lots of stuff can't be described analytically.

now imagine that i have a phd in fluid dynamics or something, and i simulate your leaf-dropping in a computer.  i tell it how to update the position of the leaf over time using equations of motion from physics.  if my code makes correct predictions, then it's asinine to say "your solution isn't analytical therefore it's wrong and/or meaningless."  the opposite is true.  i've used the laws of physics to get a numerical solution to an analytically unsolvable problem.  that's a success, not a failure.

In the article you linked the authors basically created a scenerio where three bodies moved around each other and decided that they solved the three body problem. When you make a graph with a function you are computing a pattern.

Solving the three body problem is actually much more complicated than that; it's providing a solution that will allow us to solve the problems in space and physics, where we do not know the exact "function" that brings the scenerio to its conclusion. You admitted yourself that the solution of the page was not very useful.

you are completely misunderstanding both what this paper is saying, and what an analytic solution represents.  and what a function is, if i'm being completely honest.

also i did not say that the solution from that paper is not very useful.  i said that there do exist analytic solutions to 3bp, but they are not useful.  numerical solutions are useful and make accurate predictions.  numerical solutions are computationally expensive (you're iterating lots of tiny time-steps, for example), but they're not less useful/accurate/valuable than analytic solutions.

I submit he is not misunderstanding anything.  He knows that science and logic defeat his arguments so he can't acknowledge anything that blows holes in his theories.   Fear is all it is.
Do you have a citation for this sweeping generalisation?

Offline 3DGeek

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Re: Anyone for a public discussion?
« Reply #37 on: November 13, 2017, 10:09:27 PM »
Argh - not the "three body problem" nonsense again!

The three body problem cannot be solved ANALYTICALLY - using a handy equation.  There is no equation that you can give the positions and speeds of three objects and ask "Where will they be after N seconds."

HOWEVER:

In most practical situations, one or more of the bodies are so small compared to the others that you can neglect their influence on the larger body.   So for objects like spacecraft in orbit around the Earth or the Sun or something - we have excellent math that isn't 100% accurate - but which has errors too tiny to ever matter.

Even in situations where you can't do that because all three masses are comparable in size - you can still do a stepwise approximation - and with suitably chosen time-steps, the answer can be constrained to be within reasonable bounds.   This lets you do the math more than sufficiently well to come up with a good-enough answer.

So PLEASE stop saying that NASA can't solve the problem.   Any idiot with a clue how to look up equations and the knowledge to program a computer can solve the three body problem to within whatever degree of precision you demand.
Hey Tom:  What path do the photons take from the physical location of the sun to my eye at sunset?

Offline mtnman

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Re: Anyone for a public discussion?
« Reply #38 on: November 15, 2017, 04:39:32 AM »
Tom, are you accepting or declining his invitation?

If you really believe this FE stuff, you should welcome the opportunity.


Re: Anyone for a public discussion?
« Reply #39 on: November 15, 2017, 03:48:00 PM »
I will try once more, and then sign off. If a flat-earth theorist wants to accept our invitation, please send me a private message. Transportation costs are out of the question; our Board of Directors won't allow it.

Here's why lunar (or asteroid) occultations are important to the question of the earth's shape.

In the flat earth model, to account for the ~5 degree shift in the positions of the sun, moon, planets, and stars as one moves ~350 miles north or south, you must argue that those celestial objects are no more than about 4000 miles away, from simple trigonometry. Never mind that radar measurements of the moon contradict that argument; let's go with your conspiracy theory for the moment.

The stars must be somewhat farther away than the moon, or else occultations would not occur at all, but can't be much farther because the shifts (as one moves north or south) observed for stars would be much less than for the moon (in the flat earth model), contrary to observations.

Therefore in the flat-earth model, an occultation of Aldebaran either occurs or doesn't occur depending on whether the moon crosses in front of Aldebaran. So any place where both moon and Aldebaran are visible at the right time should observe the occultation, and there would be no difference in the circumstances of the occultation (i.e. where on the face of the moon the star disappears and subsequently reappears) whether you move south or north as long as the event is above the horizon. 

What is in fact observed is that some locations on earth see a grazing occultation on the northern limb of the moon, some see a grazing occultation on the southern limb, and locations in between see the star disappear at various points around the moon. This is the effect of the moon's parallax - it is much closer to us than the star is. To demonstrate parallax: close one eye, hold your finger at arm's length so that it occults something you see out the window (a tree, chimney, mountain, whatever). Open that eye, close the other one, and the object is no longer occulted. This is one way we measure distances in astronomy.

The moon's parallax with respect to Aldebaran (or any other star it occults) implies that the star must be very much farther away than the moon. Again trigonometry can give you a (very crude) lower limit to the star's distance based on the precision with which you can measure small angles. But this would further imply that the shift in the positions of those stars as you move ~350 miles north or south on a flat earth would be much less than the ~5 degrees observed - a contradiction that can only be resolved by considering the true figure of the earth.

This coming December 31st offers a nice occultation of Aldebaran by the moon. Try it for yourselves: get an army of flat-earthers to observe the occultation from various (widely-spaced) locations, and bring them together to discuss the results. Sketches or photographs, please. Then let me know by private message whether you wish to engage in a public face-to-face discussion next April Fools' Day.

Farewell, folks, and thanks for the amusing interchange.