Is Stellarium a valid tool for being used in FET debate?
« on: December 30, 2020, 06:21:37 PM »
Is stellarium from http://stellarium.org/ accepted in FET debate as valid reference for calculating the position of celestial objects on the sky at certain time and location?

If yes, great! This would save a lot of effort in proofing evidence for several szenarios discussed in this forum.

If not for all celestial objects, is it accepted as reference for the position and movement of the sun?

Why I'm asking?

In the explanation video for the bipolar model (https://wiki.tfes.org/Bi-Polar_Model) between 1:10-1:25 stellarium is used as reference for the movement of the sun to show that the bipolar model is plausible (speaker says: "... 8 figure ... sun dance ... beautiful demonstrated by astronomy software like Stellarium as well ..." and screenshot is shown)
So I would find it strange if it would not be an accepted reference at least for the sun movement.

The great thing about stellarium is, that it is open source, so one can check what it is doing.
It uses round earth model for calculating the orientation of the observer, which is essential to show the correct position of the celestial objects.

Here is the source code for the rotation:

source file: https://github.com/Stellarium/stellarium/blob/master/src/core/StelCore.cpp
Code: [Select]
... line 923ff - this code prepares the transformation matrix to bring the objects into the right position for the observer
void StelCore::updateTransformMatrices()
{
matAltAzToEquinoxEqu = position->getRotAltAzToEquatorial(getJD(), getJDE());
...

and the called function which generates the rotation matrix getRotAltAzToEquatorial
source file: https://github.com/Stellarium/stellarium/blob/master/src/core/StelObserver.cpp
Code: [Select]
... line 240ff
Mat4d StelObserver::getRotAltAzToEquatorial(double JD, double JDE) const
{
double lat = qBound(-90.0, static_cast<double>(currentLocation.latitude), 90.0);
// TODO: Figure out how to keep continuity in sky as we reach poles
// otherwise sky jumps in rotation when reach poles in equatorial mode
// This is a kludge
return Mat4d::zrotation((getHomePlanet()->getSiderealTime(JD, JDE)+static_cast<double>(currentLocation.longitude))*M_PI/180.)
* Mat4d::yrotation((90.-lat)*M_PI/180.);
}
...

The function getRotAltAzToEquatorial adds rotation for latitude plus rotation for longitude based on the time (earth rotation).
Stellarium supports observer on earth but also on other celestial objects. All are treated as sphere.



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Offline Pete Svarrior

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Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #1 on: December 31, 2020, 01:50:21 PM »
Is stellarium from http://stellarium.org/ accepted in FET debate as valid reference for calculating the position of celestial objects on the sky at certain time and location?
You will not receive a carte blanche declaration like that from anyone. Tools are useful for their intended purposes. Stellarium is a fairly accurate representation of the RET model. It is therefore unsurprising that the maths within comes from RET, and it baffles me why you'd expect something else to be the case.

If you use it for something other than that, then you're rather blatantly misusing it.

So far, you've started 2 threads that effectively ask the same question - "Are RET sources good?". The answer will always be the same - "Yes, if you're using them to describe RET". Please can we not waste our time with repeating that question again?
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Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #2 on: December 31, 2020, 03:11:35 PM »
You will not receive a carte blanche declaration like that from anyone.

I did not expect this, opinions are welcome. This is how I see debate.

Tools are useful for their intended purposes. Stellarium is a fairly accurate representation of the RET model. If you use it for something other than that, then you're rather blatantly misusing it.

I fully agree. My question refers to the FET Wiki where Stellarium was used to underpin FET argumentation.

So far, you've started 2 threads that effectively ask the same question - "Are RET sources good?"

Yes, I try to ask as specific as I can.


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Offline Pete Svarrior

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Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #3 on: December 31, 2020, 05:57:52 PM »
I fully agree. My question refers to the FET Wiki where Stellarium was used to underpin FET argumentation.
I'm not immediately familiar with that part of the Wiki (such are the wonders of a "living document"), but I would surmise that it was used to propose that RET is self-contradictory, rather than to make an argument to the immediate benefit of FET.
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Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #4 on: December 31, 2020, 06:14:02 PM »
I fully agree. My question refers to the FET Wiki where Stellarium was used to underpin FET argumentation.
I'm not immediately familiar with that part of the Wiki (such are the wonders of a "living document"), but I would surmise that it was used to propose that RET is self-contradictory, rather than to make an argument to the immediate benefit of FET.

It is used to underpin the sun movement in the bi polar model which performs an 8 figure over the year.

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Offline Tom Bishop

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Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #5 on: December 31, 2020, 07:07:58 PM »
Stellarium is earth-only. The planetarium software you may be thinking of is Celestia, which produces the 3D model of the RE system, where you can go make views from other planets.

I have seen references in the past that Stellarium is considered to be accurate for astronomical events, and Celestia is more for entertainment purposes.

IMO, Stellarium is not based on the RE system specifically, but is based on geocentric and celestial sphere concepts.

From one of your quotes:

Quote
TODO: Figure out how to keep continuity in sky as we reach poles
   // otherwise sky jumps in rotation when reach poles in equatorial mode
   // This is a kludge

How can the sky jump in rotation if it is really the earth and observer spinning? This suggests that the sky is rotating and not the earth.

And the other one:

Quote
... line 923ff - this code prepares the transformation matrix to bring the objects into the right position for the observer
void StelCore::updateTransformMatrices()

Again, seems to suggest that the celestial objects are being brought into position for the geocentric observer.
« Last Edit: January 01, 2021, 08:48:34 AM by Tom Bishop »
"The biggest problem in astronomy is that when we look at something in the sky, we don’t know how far away it is" — Pauline Barmby, Ph.D., Professor of Astronomy

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Offline Pete Svarrior

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Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #6 on: December 31, 2020, 07:12:47 PM »
Stellarium is earth-only. The planetarium software you may be thinking of is Celestia, which produces the 3D model of the RE system, where you can go make views from other planets.
Yes, I might have the two mixed up in my head. Apologies. Nonetheless, I think my comments on the use of tools in general stand.
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Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #7 on: January 01, 2021, 08:59:59 AM »
Pete, Tom - I think 42’s question was simply whether you would accept output data from Stellarium as being accurate for the purposes of debate. For example, if we were discussing a particular constellation or star, and Stellarium says that, for a given lat/long/date/time combination, that star/constellation would be found at a given altitude and azimuth, would you accept those altitude and azimuth figures, or would you disagree with them for whatever reason? Seems reasonable to me - it simply means we can either shift the debate to whether or not the data is accurate, or whether we can all agree on the data and move on to why the stars are viewed as they are.

Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #8 on: January 01, 2021, 11:24:32 AM »
How can the sky jump in rotation if it is really the earth and observer spinning? This suggests that the sky is rotating and not the earth.

This adresses a problem with simulating a movement of the observer and it has nothing to do with real events or the model. The problem is related to the radial coordinate system used. It is independend of flat or round earth.
It happens if the programmer does not put effort on handling the movement across or nearby the pole.

Assume the observer is moving to north and also looking to north. When he crosses the pole north is in the oposite direction, which leads to a 180° turn of the observer.
I assume it has not been fixed yet because it is reasonable effort and just a "cosmetic" problem. The sky shown is correct but the U-turn might irritate the user.

Again, seems to suggest that the celestial objects are being brought into position for the geocentric observer.

This observation is absolutely correct. But don't mix up "geocentric observer" which means that the perspective is taken from location on earth with "geocentric model".
The position of the objects in a 3D space are calculated based on heliocentric model. For 2D visualization this 3D objects are projected to 2D. To do so it is necessary to rotate the objects according to the observers orientation in space - but only if RET model is used. Therefor I put it here as evidence.
In the meanwhile I found out that the documentation is a better reference than the code (right, I could have had this idea earlier).

IMO, Stellarium is not based on the RE system specifically, but is based on geocentric and celestial sphere concepts.0

Maybe you give the user documentation a read to verify your assumptions. PDF can be found on stellarium.org homepage.

Here some quotes:
"The apparent movement of the stars is due to the rotation of the Earth" => RET
"Stellarium uses the VSOP87 theory" which is heliocentric
You probably will find the word "geocentric" in the document but only in the context of "geocentric observation" which is not equal to "geocentric model".

AFAIK initial intention of Stelliarum was to simulate and support (telescope control) earth bound observations.
However Stellarium supports also space travel and observer on other planets in the solar system.
Example:

So whoever wants to state an opinion to the initial question should consider:
- Stellarium is based on RET Math (btw. I would be interested in formulas to calculate the position of celestial objects at given time & location without using RET which I have not found yet)
- Space travels and observation of the solar system from "outside" are possible


I think 42’s question was simply whether you would accept output data from Stellarium as being accurate for the purposes of debate.

Thanks for this Bob!
Maybe it was a mistake to add the RET hint to the initial question, but I wanted not to surprise someone later.
« Last Edit: January 01, 2021, 11:26:47 AM by fortytwo »

Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #9 on: January 01, 2021, 11:45:28 AM »
No worries. I’d second your point about the rotation issue at the poles. It’s got nothing to do with any flaw in RET, and everything to do with the challenge of describing the orientation of an observer. For everywhere on the planet apart from the poles, you can describe orientation with a lat/long and a direction of ‘look’. But if you tell someone to stand at the North Pole and look south, there’s an infinite number of possible directions - everywhere is south. It’s hard to accommodate that programmatically.

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Offline Pete Svarrior

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Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #10 on: January 01, 2021, 01:22:29 PM »
Pete, Tom - I think 42’s question was simply whether you would accept output data from Stellarium as being accurate for the purposes of debate.
I get that, but, as I said before, the answer is "it depends". No one is going to pre-approve a tool without knowing what argument you're trying to make.

As an attempt at generalising some of the common categories: If you're trying to correct someone's misconceptions about RET, I'd say yes. If you're trying to make a point about FET, I'd say categorically no. If you're trying to make a determination as to which model better represents reality: it could be part of a bigger puzzle, but certainly not the only piece of evidence. If you're trying to use it as a direct substitute for real observation (i.e. simply claim that it represents reality) - categorically not.
« Last Edit: January 01, 2021, 01:24:22 PM by Pete Svarrior »
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Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #11 on: January 01, 2021, 01:43:10 PM »
Pete, Tom - I think 42’s question was simply whether you would accept output data from Stellarium as being accurate for the purposes of debate.
I get that, but, as I said before, the answer is "it depends". No one is going to pre-approve a tool without knowing what argument you're trying to make.

Why would it depend on the argument being made? It’s simply data pertaining to the azimuth and elevation angle of the stars as viewed from the surface of the earth. You either agree that the data is accurate, or you don’t. Whether you’re supporting FET or not, it’s just numbers. They’re either right or wrong - you can go outside and verify them yourself. If you’ve spotted some massive issue with the data, then let’s hear it. If you agree that’s it’s essentially accurate, then we can move on and use the data to support or contest each other’s arguments.

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Offline Pete Svarrior

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Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #12 on: January 01, 2021, 01:50:48 PM »
Why would it depend on the argument being made?
Because it's a mathematical representation of RET. You can't use it as anything other than that.
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Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #13 on: January 01, 2021, 02:30:20 PM »
Because it's a mathematical representation of RET. You can't use it as anything other than that.

No, that’s not a good description at all. If it tells you,  for example, that a particular star is at 020 degrees true, 34 degrees elevation, at 0230UTC, at a particular lat/long, then that’s either true or false. We’re asking to you either agree that the data is verifiably robust, or to challenge it somehow. Agreeing that it’s accurate doesn’t mean you have to agree that the earth isn’t flat.

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Offline Pete Svarrior

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Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #14 on: January 01, 2021, 04:21:14 PM »
that’s either true or false
I already explained this twice, but perhaps a third time will help: we can agree on (possible) correlation. We will not agree on causation. Stellarium is a mathematical representation of some concepts of RET - nothing more, nothing less, at least in isolation.

I'm sorry that you dislike this, but the question has been asked and answered. We're not going to go down the rabbit hole of you repeatedly complaining that you disagree.
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Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #15 on: January 01, 2021, 05:41:23 PM »
Quote
: we can agree on (possible) correlation.

Ok, well that’s great - so you agree it’s a good representation of where the stars appear. Thanks - that’s all that was needed.

Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #16 on: January 01, 2021, 06:36:06 PM »
Thanks guys, so I try to summarize my understanding of what was suggested here.
- RET based tool can be used to demonstrate how RET works and how celestial movements and events can be explained with RET
- RET based tool can be used to challenge RET e.g. if something is observed what cannot be simulated or explained with RET
- RET based tool cannot be used to challenge FET
- RET based tool should not be used to proof or unterpin FET (maybe this is also changed in the Wiki-video mentioned in inital post someday)
And same vice versa (if there is any FET based tool)

I don't know if there is any non RET or model agnostic tool available for sky observations which then could be used to support FET, I don't think so.
But this should not be a problem because AFAIK FET currently does not make any predictions which could be checked.

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Offline Tom Bishop

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Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #17 on: January 02, 2021, 02:03:52 AM »
It's not clear that Satellirium is actually based on a plain RET model. You said that Stellarium uses heliocentric VSOP. But what is VSOP?

https://en.wikipedia.org/w/index.php?title=Talk:VSOP_(planets)&oldid=610626270

Quote
Comparing VSOP and the Ptolemaic system.

Modelling VSOP on a ubiquitous PC computer program, starting with only one element for each of the three parameters (L, B R) and then slowly incrementing the number of elements, gives a sense of irony that it is in fact nothing more than a more complex development of the ancient deferent / epicycle system used by Ptolemy. A system that despite being totally dismissed out of hand for being intellectually "wrong", was able to provide a prediction service accurate enough to match the observational resolution available (naked eye, with no reliable mechanical timekeeping). A system that, astoundingly to this author, was able to detect and measure, accurately, the lunar evection, one of the still-used perturbations of the Earth-Moon system. Summing powers of sines and cosines is certainly tantamount to circles upon (or perhaps within) circles; recursing, or perhaps simply nesting, almost endlessly. Whilst of course this is totally irrelevant to the mathematics, it perhaps behooves Wikipedia's wider terms of reference to include this as a philosophical point.

From The Logical Leap: Induction in Physics by David Harriman:

https://books.google.com/books?id=aXU2AAAAQBAJ&lpg=PT38&ots=zNE0nJr1Qw&pg=PT37#v=onepage&q&f=false

Quote
The circle is the geometric figure possessing perfect symmetry, so Ptolemy and earlier Greek astronomers began with the intuition that celestial bodies orbit in circles at uniform speed. Observations then determined the deviations from the ideal, which Ptolemy modeled using mathematical contrivances unrelated to physical principles (deferents, epicycles, and equants).

...Ptolemy’s science was superficially anti-Platonic in that he emphasized the role of careful observation. However, at a deeper level, his science was a logical application of Platonism; in astronomy and in optics, he started with the “perfect” model and then merely described without explanation the inherently unintelligible deviations from it.

Here Celestia Developers comment on the large number of planet-specific terms in VSOP used in computing positions:

http://archive.fo/lVaD6

  “ VSOP87 is a set of polynomials describing the orbits of the major planets. There are over 1000 terms in each series. ”

http://archive.fo/UvfhI

  “ I could add more terms to the VSOP-87 series, but there are already over 1000 per major planet ”

What exactly are these "terms" which are individual to each planet, and how can you assure us that it is based on natural laws from a simple RE model and that none of it is ad-hoc like Ptolemy's epicycles were?
« Last Edit: January 02, 2021, 03:01:01 AM by Tom Bishop »
"The biggest problem in astronomy is that when we look at something in the sky, we don’t know how far away it is" — Pauline Barmby, Ph.D., Professor of Astronomy

Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #18 on: January 02, 2021, 09:08:21 AM »
Quote
What exactly are these "terms" which are individual to each planet, and how can you assure us that it is based on natural laws from a simple RE model and that none of it is ad-hoc like Ptolemy's epicycles were?

It's an interesting discussion, but does it matter here? 42's original question, as per my discussion with Pete above, was whether the output of Stellarium would be accepted as a valid source of data for the apparent position of celestial objects. If it's saying that a particular star is going to appear due south, 42 degrees above the horizon, at 2245UTC viewed from London, then isn't the question simply whether you agree that it does? It doesn't matter what the data source actually is - it can be viewed, I would suggest, as a black box until such time as you find significant errors in the output. 

Re: Is Stellarium a valid tool for being used in FET debate?
« Reply #19 on: January 02, 2021, 10:51:48 AM »
@Tom
The thread was not intended to discuss if Stellarium is RET based, it was my mistake to mention it in the initial post.
We provided the relevant links and whoever is interested in the topic can inform himself. More selective quotes would not help anyone, so I don't continue on that.

I would suggest that whoever is using Stellarium or any other tool to unterpin FET arguments should consider that it could potentially be RET based.
I would also wonder, what the alternative to heliocentric and RET based could be. I don't know any alternative theory which offers prediction of celestial events.
« Last Edit: January 02, 2021, 10:58:17 AM by fortytwo »