Ptolemaic System simulator- Earth orbit unavoidable?

[buggs_moran]

Two more links for you Andrea. The first has some more heavy duty math and is by Giovanni Gallavotti, Universit`a di Roma ?€?La Sapienza?€

[ANDREA]

[quote="buggs_moran"]Two more links for you Andrea. The first has some more heavy duty math and is by Giovanni Gallavotti, Universit`a di Roma ?€?La Sapienza?€

[buggs_moran]

Well, after some time on this project I have come to a couple conclusions.

1) I like your model better Andrea. The data I was going off of was making the model not as informative (or pretty) I get too embroiled in the details and though it my be to "scale", it lacks what I liked about yours in the first place. The barycenter model works, but is not as clean.

I did find some data on deferent radii, but nothing on epicycles
Planet.........in Earth r..........in AU
Moon................60.3........0.0026
Mercury............10...........0.0043
Venus.............600...........0.0256
Sun..............1200............0.0512
Mars.............5000............0.2132
Jupiter.........11500............0.4903
Saturn.........17000............0.7248
Universe......20000............0.8527

2) It's a good thing no one could see this model to scale back then.
3) I did manage to create a "celestial sphere" using data from Ptolemy's Amalgest (1028 stars). I might work on this though to give it more of that drawing look that you wanted. Note Ursa Minor to the top of the second picture.

[ANDREA]

Well, after some time on this project I have come to a couple conclusions.
1) I like your model better Andrea. The data I was going off of was making the model not as informative (or pretty) I get too embroiled in the details and though it my be to "scale", it lacks what I liked about yours in the first place. The barycenter model works, but is not as clean.

Buggs, I agree with you. Regarding the orbit lines, I see that the Earth has not its own. How did you obtain this?

I did find some data on deferent radii, but nothing on epicycles
Planet.........in Earth r..........in AU
Moon................60.3........0.0026
Mercury............10...........0.0043
Venus.............600...........0.0256
Sun..............1200............0.0512
Mars.............5000............0.2132
Jupiter.........11500............0.4903
Saturn.........17000............0.7248
Universe......20000............0.8527

I'll make a try with these distances, but I'll grow up the planets/Sun/Moon radii for aestethics needs. BTW, Mercury should be 100 in earth radii.

2) It's a good thing no one could see this model to scale back then.
3) I did manage to create a "celestial sphere" using data from Ptolemy's Amalgest (1028 stars). I might work on this though to give it more of that drawing look that you wanted. Note Ursa Minor to the top of the second picture..

I like the final result of your celestial sphere. Anyhow I would try to add stars with an "ancient" style, just to remember that these Universe models are dated very back in human history.
Bye and many thanks, Buggs.

Andrea

[buggs_moran]

Regarding the orbit lines, I see that the Earth has not its own. How did you obtain this?

It is a totally separate system set apart from the Sol system in Celestia. The system is set up with orbiting barycenters as shown below. Then, in an ssc file, I defined the epicycle orbits around the barycenters for each planet. The major downfall of this method is the loss of orbit lines (as Selden noted above), which I artificially added into the ssc file (i.e. the planet barycenter in stc and planet deferent in ssc are the same and redundant). If we could see barycenter and star orbits (HINT HINT you programmer types), this would not be a problem.

Code: Select all

Barycenter "Deferent"
{
RA 0.0 # (h:m:s)
Dec 0.0 # (deg:m:s)
Distance 0
}

Barycenter "B.Earth" # Earth Barycenter
{
OrbitBarycenter "Deferent"
EllipticalOrbit
{
Period        1.0
SemiMajorAxis     0.000256
MeanAnomaly     0.0
}
}

Barycenter "Equant"
{
OrbitBarycenter "Deferent"
EllipticalOrbit
{
Period        1.0
SemiMajorAxis     0.000256
MeanAnomaly     180.0
}
}

Barycenter "B.Mercury"
{
OrbitBarycenter "Equant"
EllipticalOrbit
{
Period        1.0
SemiMajorAxis     0.0043 # 100 x Radius Earth
}
}

etc.


I'll make a try with these distances, but I'll grow up the planets/Sun/Moon radii for aestethics needs. BTW, Mercury should be 100 in earth radii.

Oops...

[ANDREA]

It is a totally separate system set apart from the Sol system in Celestia. The system is set up with orbiting barycenters as shown below. Then, in an ssc file, I defined the epicycle orbits around the barycenters for each planet. The major downfall of this method is the loss of orbit lines (as Selden noted above), which I artificially added into the ssc file (i.e. the planet barycenter in stc and planet deferent in ssc are the same and redundant). If we could see barycenter and star orbits (HINT HINT you programmer types), this would not be a problem.

Hello Buggs, let's hope that someone will give us some help on this matter, but I suppose the problem be not simple, because it has been asked for in other posts, without results.
I tried the Ptolemaic system with the right deferent radii you gave me, but in this way it becomes a very "sparse" system, I mean that it's correct but invisible in its complex (and complexity), so looses its educational aim, IMHO.
I think I'll remain with the old radii data, as shown in my first image.
Bye

Andrea

[buggs_moran]

I tried the Ptolemaic system with the right deferent radii you gave me, but in this way it becomes a very "sparse" system, I mean that it's correct but invisible in its complex (and complexity), so looses its educational aim, IMHO.
I think I'll remain with the old radii data, as shown in my first image.
Bye

Andrea

Agreed. That is exactly what I was getting at when I said I liked your system over mine a few posts back. Yours definitely has more educational value since you can "see" what Ptolemy has in mind. He must have imagined something much different than the math presented. I imagine Ptolemy had problems with this. Nice perfect spheres with vast spaces (even if those vast spaces weren't as big as we are used to) are hard to express on a sheet of paper. (Heh, especially without logarihtmic scales which I believe, didn't start appearing until the 1200's on paper.)

[buggs_moran]

Andrea,

I managed to map all 1028 stars in Ptolemy's Amalgest. If you give me the distance you want to the stars I can rerun my program with the new info. I just have to readjust star sizes. Right now they are sized based on Ptolemy's magnitudes for 1/2 light year distance (way more than Ptolemy's 20000 Earth radii). Note (edit: Orion to the right and down from Earth), lots of fun...

[ANDREA]

Andrea, I managed to map all 1028 stars in Ptolemy's Amalgest. If you give me the distance you want to the stars I can rerun my program with the new info. I just have to readjust star sizes. Right now they are sized based on Ptolemy's magnitudes for 1/2 light year distance (way more than Ptolemy's 20000 Earth radii). Note Ursa Major and Minor, lots of fun....

Hello Buggs, very, very, very nice indeed! I love it.
Here you can find the ssc file I used for my Ptolemaic System:
http://www.palatinumclub.it/ptolemaic_solarsys.ssc
As you see the Saturn distance is set at 45,000,000, so I think that the StarSphere should be at about 55-65,000,000 , neither too close to Saturn not too large to reduce SolarSystem proportions.
Regarding star size, if we take the second image aspect and dimensions, I think that stars should be a bit smaller, otherwise will clutter the planets.
What is your opinion?
Thanks a lot for all what you are doing, Buggs, very appreciated.
Bye

Andrea