Kepler's solar system model (work in progress)

[Cham]

Today, while working on a model of Mercury, I had the idea to reproduce Kepler's first model of the solar system. I already talked about it last week to my astronomy classe, so it may be usefull to show it in full 3D to my students, next semester.

Here's the original work of Kepler (click the thumbnail, for a larger picture) :



Here's an early test prototype in Celestia :



I'll probably make the spherical bowls in metallic-copper and the platonic shapes in wood, or with a different color so we can see the various shapes clearly.

Any suggestions to improve the model ?

[chris]

Neat! How about a wireframe version of the nested regular polyhedra that's solar system scale, so we could see how Kepler envisioned the correspondence between their sizes and the orbits of the planets?

--Chris

[Cham]

I could make the polyhedras semi-transparent.

For the moment, I still don't know if I should use some realistic materials for the parts (rusted metal, copper, wood, etc), or just some abstract materials. Maybe I'll make the hemi-spheres as cristal balls (semi-transparent spheres)

Here's a page describing Kepler's model with details :

http://galileoandeinstein.physics.virgi ... epler.html

[ANDREA]

I could make the polyhedras semi-transparent.
For the moment, I still don't know if I should use some realistic materials for the parts (rusted metal, copper, wood, etc), or just some abstract materials.

Oh yes, Cham, please, use those old nice materials, that were used for all the scientific educational instruments up to not so many years ago (in my youth we still had many of them in the science laboratory).
Anyhow, a very interesting project, well done.
Bye

Andrea

[Cham]

The problem I'm experiencing with the model, right now, is the thickness of the objects (polyhedras and orbs). It's very hard to make all of them in the proper proportions. It's very easy to do if I don't give them a thickness, so in this case the materials will be abstract semi-transparent ones. I'll still try to give some thickness, so I can use some real-looking materials. It's harder than what I believed at first.

Here's an abstract representation. I'm not satisfied with the depth sorting of the polyhedras, and I prefer to add some thickness to the orbs :



I want to make the model to scale, add a star in the center, and the planets moving on the orbs...

[ANDREA]

The problem I'm experiencing with the model, right now, is the thickness of the objects (polyhedras and orbs). It's very hard to make all of them in the proper proportions. It's very easy to do if I don't give them a thickness, so in this case the materials will be abstract semi-transparent ones. I'll still try to give some thickness, so I can use some real-looking materials. It's harder than what I believed at first.

Well, take it easy, Cham, mine was only a hope, not a request.
Probably I have a bit of nostalgy for the oldies when there was not all this (CENSORED) plastic!
Whatever you'll do will be very appreciated.
Bye

Andrea

[Cham]

Don't worry, Andrea, my goal was already to add thickness and "oldish" materials. So I'll really try to make it the way I intended. In the meanwhile, the abstract version is already pretty nice (click to enlarge) :



With the recent option (Clickable false) in the SSC, it will certainly be great to feel inside, clicking on the moving planets (to be added later), without the possibility to click the model itself. I just can't believe how life is easier now, with that option !

[Cham]

Hmm, there's a problem when I place a star in the middle of the model. Illumination isn't right (the model is all black). If I place the model slightly off the center, there's an illumination which doesn't make any sense (this was expected, however), and the star itself may even disappear if the observer is rotating around it. This appears to be another depth sorting issue. So, I'll have to place a fake star in the center instead, evolving far away around some true star.

[Cham]

Somebody knows the names of the planets in latin, at the time of Kepler ?

The model with thickness is done. I wont add some "realistic" textures (rusty metal, wood, etc), since they will make the model confused. I think it's already nice with this rendering :



Personally, I don't think Kepler's model is really interesting to see, in Celestia. It's so ... unnatural !

For comparison, here are the orbital radius in Kepler's model (left values), compared with the real ones (right values) :

Mercury : 0.4026 UA -- 0.3871 UA (4.0% discrepancy)
Venus : 0.7540 UA -- 0.7233 UA (4.2%)
Earth : 1 UA -- 1 UA (0% by definition)
Mars : 1.3060 UA -- 1.5237 UA (14%)
Jupiter : 4.0044 UA -- 5.2034 UA (23%)
Saturn : 7 UA -- 9.5371 UA (27%)

[ANDREA]

[quote="Cham"]Somebody knows the names of the planets in latin, at the time of Kepler ?[quote]
Here are Latin names:
Sol
Mercurius
Venus
Terra
Luna
Mars
Jupiter
Saturnus

and I found no evidence of different naming at Kepler's time.
Bye

Andrea

[Cham]

Thanks, Andrea. I made the changes. I named the central star "Kepler", as to not confond with our Sol.

Too bad Mars and Jupiter aren't "Marsus" and "Jupiterus" in Latin.

[ANDREA]

Thanks, Andrea. I made the changes. I named the central star "Kepler", as to not confond with our Sol.
Too bad Mars and Jupiter aren't "Marsus" and "Jupiterus" in Latin.

He he!
We could ask to Julius Caesar's soul if he agrees, who knows...
Bye

Andrea

[ANDREA]

Cham, regarding Solar System ancient models, just a doubt: do you think it could be possible to reproduce in Celestia a working model of a Mechanical Orrery, like the ones found here:
http://www.oobject.com/category/mechani ... ry-models/
or like these ones:









I don?€™t know if this coud be interesting for you, but I find them fascinating, aren?€™t they?
Bye

Andrea

[Cham]

Oh boy, this kind of toys, it's certainly possible to make them for Celestia. But personally, I don't think it's really worth it. The only "models" I'm still interested in are the old ptolemaic system (with epicycles), and maybe Tycho's version. About the Ptolemaic system, have you finished the one you were building, last year ?

[ANDREA]

:o Oh boy, this kind of toys, it's certainly possible to make them for Celestia. But personally, I don't think it's really worth it.

Well, sorry you are considering them as "toys", because as you know many of them were true masterpieces of mechanical engineering, and moreover used for educational purposes (like many of us, like you and me, do with Ce??lestia).
I think instead it could be a very interesting "historical" addition to the real wonders shown by Celestia.
A matter of opinions, obviously, so I hope that someone else could be interested on this addon.

The only "models" I'm still interested in are the old ptolemaic system (with epicycles), and maybe Tycho's version. About the Ptolemaic system, have you finished the one you were building, last year ?

Cham, I'm sorry for the long delay, but Buggs Moran has very little time left from his job, so the project is going on very slowly.
Anyhow, just a couple days ago Buggs showed me its first result on the "Homeric Solar System", you know, the one with flat Earth, Ocean River surroundind it, and the Moon, Sun and star sphere all around.
This is the last one to be finished, but we have some minor problem with other Systems, including the Ptolemaic one, that we'll solve as soon as possible.
I'll inform the forum as ready for release.
Be patient, please, some more time.
Bye

Andrea

[buggs_moran]

Actually I like our Ptolemaic one. Hopefully we can tie up loose ends soon. As for Homeric, I will post the shot I showed Andrea. I am somewhat satisfied with it...

[Cham]

Buggs,

This model is interesting. Where's Homer Simpson, on the islands ? (jk)
Can you show the bottom side too ? (or better, send me the model by email)

And can you show more, on the planets orbits in that world ? What about the celestial sphere around the homeric world ? Is there any ?

Personally, I need to show the Ptolemaic system (and maybe Tycho's system) to my students. I don't need Homer's world, but it may be fun too.

[buggs_moran]

And can you show more, on the planets orbits in that world ? What about the celestial sphere around the homeric world ? Is there any ?

Personally, I need to show the Ptolemaic system (and maybe Tycho's system) to my students. I don't need Homer's world, but it may be fun too.

Thanks Cham. Nowhere near the quality of your models... The bottom side is not filled in. You cannot see it because I made the bottom hemisphere black (that may change). I am debating how to show the celestial sphere. It's...tricky. I though about using my Almagest sphere I created for the Ptolemy system (tres cool)... That would explain stars in the sky during an eclipse. I have no intention of going crazy with planets. I might throw them in so one could sit on the Peloponesian peninsula and watch the "wanderers..." Good for teaching if nothing else...

As far as Ptolemy goes I am very satisfied with our system. We have a scaled down big planet "orrery" version and a "to scale" version. I mapped the stars in the Almagest to a sphere. It's really cool to sit in Alexandria and see the path of all of the bodies. It's not perfect, but I think we did a good job estimating the system. Most of the data used is to Ptolemy's numbers within reason. Actually getting Ptolemy's system to work is practically impossible. Much work has been done on this from what I've read and it never works just right.

The Tychonic system we planned will be a working system. Your model would be great to show within Celestia when teaching that system. I am pretty sure Andrea's ultimate goals include scripts for tours through each historical system.

[ANDREA]

Actually I like our Ptolemaic one. Hopefully we can tie up loose ends soon. As for Homeric, I will post the shot I showed Andrea. I am somewhat satisfied with it...

Me too, but with a little suggestion: at Homer time the only passage to Ocean River was the Hercules Columns passage (Gibraltar), while in your model there is another wide passage left of Italy.
IMHO it could be like this:



Moreover, as shown in your second image, Africa looks with high mountains in the south, while I think that the knowledge of the African desert was not so good.
Perhaps only the Atlas Mountains, in Morocco, could be known because perhaps visible from the Mediterranean coast.
Anyhow, I suggest you to make a flatter Africa.
Just an opinion.
Bye

Andrea

[ANDREA]

Chris (Buggs), please give a look at your PM.
Bye

Andrea