<p>I don't know any software library which does what you require. But there is an account of the geocentric model in terms of modern mathematics (vector algebra etc) written by Professor Richard Fitzpatrick of the university of Texas. It is called
<strong>&quot;A Modern Almagest. An Updated Version of Ptolemy's Model of the Solar System&quot;</strong>
and available in html or pdf at:
<a href="https://farside.ph.utexas.edu/books/Syntaxis/Syntaxis.html" rel="nofollow noreferrer">https://farside.ph.utexas.edu/books/Syntaxis/Syntaxis.html</a>
The procedures described in this book can be used to develop such a software library.</p>
<p>As we know today from the works of Copernicus and his successors the heliocentric system is the right one and describes the motion of the earth/moon/sun/planets very precisely.</p>
<p>Kind Regards
Klaus</p>

CC BY-SA 4.0
2022-09-29T10:08:08.847Z
2022-09-29T10:08:08.847Z
Klaus Rohe
<p>I think no one claims that assuming the earth is at the center of everything makes orbit predictions impossible. (For that matter, the apparent homogeneity of the cosmic background radiation seems to suggest that there <em>is</em> no &quot;center&quot; of the universe, etc.) It just makes things messier. That's partly why &quot;local&quot; problems like getting a spaceship to the moon, or to Mars, that do need to refer to Earth as a &quot;ground point&quot;, become crazy, in comparison to two-body or restricted three-body problems.</p>
<p>But/and, yes, NASA in-effect has software that does such computations for Earth-to-X stuff!</p>
<p>That (also!) does not mean that the Earth is anywhere near the center of mass of the solar system. The sun is. And our solar system is nowhere near the center of mass of our galaxy. And ...</p>
<p>So, in some regards, the whole question of geocentric versus heliocentric doesn't really have content... at least insofar as there <em>is</em> no center, anyway, ... That kind of thing.</p>
<p>EDIT: the Community Bot has made some well-intentioned &quot;suggestions&quot; about editing-to-improve. Ok. But I am inclined to think that my minor reframing of the question answers it better than a literal response. Sure, opinions vary...</p>

CC BY-SA 4.0
2022-09-28T22:59:47.663Z
As it’s currently written, your answer is unclear. Please [edit] to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers [in the help center](/help/how-to-answer).
Community
CC BY-SA 4.0
2022-09-28T18:41:30.090Z
2022-09-28T23:06:26.397Z
2022-09-28T23:06:26.397Z
paul garrett
<p>is there any software library that calculates earth/moon/sun/planets positions based on the geocentric model?</p>
<p>if that exists, why is the heliocentric model the most popular?</p>

CC BY-SA 4.0
2022-09-28T09:10:11.393Z
Claudius Ptolemy did have such a model, a long time ago. That model was tossed by Nicolaus Copernicus, Galileo di Vincenzo Bonaiuti de' Galilei, Johannes Kepler, Isaac Newton, Albert Einstein, along with others.
David Hammen
CC BY-SA 4.0
2022-09-28T13:44:04.497Z
The heliocentric model is most popular because it is correct
Rory Alsop
CC BY-SA 4.0
2022-09-28T19:33:36.657Z
When you say "The geocentric model" which one do you mean.  There were many developed, mostly adding a tweak here or there to make the predictions more accurate.  The best known one is that of Ptolemy but there were lots of others.  So which geocentric model are you asking about?
James K
CC BY-SA 4.0
2022-09-28T22:13:26.180Z
The heliocentric model isn't really the defacto model either, the most accurate models are n-body simulations where no body is the center.  The idea of kelperian orbits are simplifications that make visualizing easier, but are not that accurate.
Greg Miller
CC BY-SA 4.0
2022-09-29T01:14:39.680Z
I don’t know of any such library. As Rory Alsop points out, the heliocentric model is correct, while the geocentric one is not. Contrary to what Paul Garrett mentions, though, NASA’s model is not geocentric, even though it does allow geocentric *coordinates* to be determined. I have recently translated Ptolemy’s Almagest to French, including some animations. I could probably provide you with some useful code of a geocentric *model*, even though it’s wrong and imprecise because that’s not how nature works.
Pierre Paquette
<software><geocentrism>
software library that calculates earth/moon/sun/planets positions based on the geocentric model
geek
# software library that calculates earth/moon/sun/planets positions based on the geocentric model

(Asked by: username_0 on 2022-09-28)

is there any software library that calculates earth/moon/sun/planets positions based on the geocentric model?

if that exists, why is the heliocentric model the most popular?

**Tags:** software, geocentrism

> **Comments:**
> **username_1**: Claudius Ptolemy did have such a model, a long time ago. That model was tossed by Nicolaus Copernicus, Galileo di Vincenzo Bonaiuti de' Galilei, Johannes Kepler, Isaac Newton, Albert Einstein, along with others.  
> **username_2**: The heliocentric model is most popular because it is correct  
> **username_3**: When you say "The geocentric model" which one do you mean.  There were many developed, mostly adding a tweak here or there to make the predictions more accurate.  The best known one is that of Ptolemy but there were lots of others.  So which geocentric model are you asking about?  
> **username_4**: The heliocentric model isn't really the defacto model either, the most accurate models are n-body simulations where no body is the center.  The idea of kelperian orbits are simplifications that make visualizing easier, but are not that accurate.  
> **username_5**: I don’t know of any such library. As username_2 points out, the heliocentric model is correct, while the geocentric one is not. Contrary to what Paul Garrett mentions, though, NASA’s model is not geocentric, even though it does allow geocentric *coordinates* to be determined. I have recently translated Ptolemy’s Almagest to French, including some animations. I could probably provide you with some useful code of a geocentric *model*, even though it’s wrong and imprecise because that’s not how nature works.  

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## 2 answers

### Answer by username_6 on 2022-09-29. Score: 3 | Accepted answer

I don't know any software library which does what you require. But there is an account of the geocentric model in terms of modern mathematics (vector algebra etc) written by Professor Richard Fitzpatrick of the university of Texas. It is called
**"A Modern Almagest. An Updated Version of Ptolemy's Model of the Solar System"**
and available in html or pdf at:
<https://farside.ph.utexas.edu/books/Syntaxis/Syntaxis.html>
The procedures described in this book can be used to develop such a software library.

As we know today from the works of Copernicus and his successors the heliocentric system is the right one and describes the motion of the earth/moon/sun/planets very precisely.

Kind Regards
Klaus


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### Answer by username_7 on 2022-09-28. Score: 2

I think no one claims that assuming the earth is at the center of everything makes orbit predictions impossible. (For that matter, the apparent homogeneity of the cosmic background radiation seems to suggest that there *is* no "center" of the universe, etc.) It just makes things messier. That's partly why "local" problems like getting a spaceship to the moon, or to Mars, that do need to refer to Earth as a "ground point", become crazy, in comparison to two-body or restricted three-body problems.

But/and, yes, NASA in-effect has software that does such computations for Earth-to-X stuff!

That (also!) does not mean that the Earth is anywhere near the center of mass of the solar system. The sun is. And our solar system is nowhere near the center of mass of our galaxy. And ...

So, in some regards, the whole question of geocentric versus heliocentric doesn't really have content... at least insofar as there *is* no center, anyway, ... That kind of thing.

EDIT: the username_8 Bot has made some well-intentioned "suggestions" about editing-to-improve. Ok. But I am inclined to think that my minor reframing of the question answers it better than a literal response. Sure, opinions vary...

> **Comments:**
> **username_8**: As it’s currently written, your answer is unclear. Please [edit] to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers [in the help center](/help/how-to-answer).  

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