Celestial sphere models

[Laurence Finston]

Hello,

This is my first post to these forums.

I have just completed the plans for two celestial sphere models. They can be found here: https://www.gnu.org/software/3dldf/g...s/clstsph1.pdf

The webpage they're on is here: The GNU 3DLDF Astronomy Page

And finally the main page for the website is here: The GNU 3DLDF Website

I need to add specific instructions for the models but they are probably not needed by users of these forums.

The two models are provided in two versions, white on black and black on white. They include the 200 brightest stars, except for Polaris, which would have been at an inconvenient location on the models, namely at the north pole.

The first model is made up of spherical biangles. They should not be folded but rather bent and attached to each other using the tabs on the left side.

The second model uses what I'm calling "panels". While the left and right sides of the sections appear to be curved, they are in fact made up of straight lines. The sections should be folded on the horizontal lines (latitude) and again attached using the tabs. The result is an irregular polyhedron approximating a sphere.

The "globes" on pages 10-11 are just to illustrate how the positions of the stars on the spherical biangles and panels were derived.

Please _don't_ print out pages 12-17! The license is important but it would just be an unnecessary waste of paper to print it out.

Please note the disclaimer on page 1!

There are plans for various other models on the website, e.g., here: The GNU 3DLDF Sphere and Dome Models Page

It's been awhile since I last worked on them. One of these days I plan to consolidate them and put them together in book form.

Any "bug reports" or feedback would be much appreciated.

Laurence Finston

[asettico]

Hello Laurence,
welcome from Italy!

Thank you for sharing the project and tankful for boosting the GNU project!

[THE DC]

Thus is a great resource!

I am gong to print these stellar sphere's tonight. They will be greta for teaching youth astronomy.

I wish someone would make such globes of the moon, Mars, Venus, and other celestial bodies that have been mapped.


Thanks again for the great resource!

[Laurence Finston]

Thank you very much, asettico and THE DC!

For a previous version, I also printed out info about the stars, right ascension and declination, actual and apparent brightness and on which spherical biangle they appeared. However, I used degrees, minutes and seconds for the right ascension because I used those values for rotating the stars to the correct positions on the 3D sphere used internally by the program. The data on the stars is stored in a database and I have the right ascension values in hours, minutes, seconds, so I just have to sit down and do the work. As I make corrections and/or additions, I'll post new versions to the website.

The SQL code for the MySQL database is included in the package; not in the downloadable version, but in the Git repository. If anyone's interested, I'll elaborate.

The longitudes of the stars are found by rotating counter-clockwise from right ascension 0h 0m 0s. I believe that the result of this is that the model represents the celestial sphere as seen by an observer looking at it from the outside. I hope someone will correct me if I'm wrong. One of the famous early star atlases is also this way, so I think it's alright.

However, in principle it wouldn't be difficult to reverse the representation. The difficulty would be in reversing the labels, but I think this problem can be solved.

Positioning the labels was one of the most time-consuming parts of making the model. Otherwise, it would be a snap to print out the model in different sizes. I may be able to find a solution for keeping the labels in the correct position and changing the font sizes when magnifying or shrinking.

I could also easily make PDFs with different paper sizes, if anyone needs them.

The next thing I want to work on is including the planets in their positions on any given day. Then people could print out a version with the planets in their positions on their birthdays, anniversaries or whatever. This involves time calculations which are kind of tricky. I'm still learning about this.

I like the idea of sphere models representing the moon, planets, etc. However, I would need geographic data in a more-or-less machine-readable form and I'm not sure this is available. I'll look into this when I get a chance or maybe ask at an observatory.

Thanks again for the feedback!

[Laurence Finston]

Originally Posted by Laurence Finston

For a previous version, I also printed out info about the stars, right ascension and declination, actual and apparent brightness and on which spherical biangle they appeared. [...]

I found I still had this document and have posted it to the website:

https://www.gnu.org/software/3dldf/g...lstsph1_a4.pdf

However, I haven't yet changed the degrees to hours for the right ascension. Still, I think the model will be much more useful with this data.

[Laurence Finston]

Originally Posted by THE DC

They will be greta for teaching youth astronomy

Is this what you're doing? Please let me know if you have any "special requests". I mentioned the possibility of changing sizes.

I have data for the constellation boundaries. I would like to plot the edges on the models. As I'm sure you know, if you're an amateur or professional astronomer, this is fairly complicated.

Another improvement which wouldn't take too much effort would be to put labels for the lines for the declination and right ascension on the models. I'll probably do this next.

[THE DC]

Originally Posted by Laurence Finston

Is this what you're doing? Please let me know if you have any "special requests". I mentioned the possibility of changing sizes.

I have data for the constellation boundaries. I would like to plot the edges on the models. As I'm sure you know, if you're an amateur or professional astronomer, this is fairly complicated.

Another improvement which wouldn't take too much effort would be to put labels for the lines for the declination and right ascension on the models. I'll probably do this next.

These are great idea!

I have a teacher who works with some young kids who cab really benefit from this. He's always looking to improve his astronomy efforts.

I also work with some youth who like to build space craft but I will see about introducing some celestial tools!!!

[Laurence Finston]

Originally Posted by Laurence Finston

Another improvement which wouldn't take too much effort would be to put labels for the lines for the declination and right ascension on the models. I'll probably do this next.

I worked on this last night. I should finish it today and will post the revised version on the website.

Originally Posted by THE DC

These are great idea!

I have a teacher who works with some young kids who cab really benefit from this. He's always looking to improve his astronomy efforts.

I also work with some youth who like to build space craft but I will see about introducing some celestial tools!!!

Please let me know how it works out. I think the models should be easy enough to build for kids. The only difficulty is to keep the spherical biangles from slipping while attaching them to each other. Maybe there's a fast-setting glue that would help.

On an earlier sphere development model (without stars), I printed dots for sewing, if the builder chose to sew it together. I tested this and found that sewing works well. However, working with black thread on a black background is difficult, so I don't know how this would work with the white-on-black version of the celestial sphere model. It might be possible to use another color of thread, use glue or paste in addition to the thread and snip off the thread when the glue/paste is dry.

By the way, the limit of 200 stars is arbitrary. There is data for over 1400 stars in the database. For a larger version of the model I would use more stars. It would require some work, because I don't have the apparent magnitude for all of the stars yet. However, making plans for a model with a radius of, say, 10cm, and 300 stars is something I could see working on pretty soon. (The radius of the current model is 7cm --- a little smaller than I'd visualized it.)

[Laurence Finston]

Another set of plans with an astronomical flavor, which might be of interest to you or the teacher you know, is here: https://www.gnu.org/software/3dldf/g...s/sundl_03.pdf

This is the webpage: The GNU 3DLDF Sundials Page

They are plans for sundials at various locations. They only account for vertical and horizontal dials. It would be possible to make them for other orientations but I made them in 2007 and I'd need to review how this works.

If anyone wants plans for a different location, I would be glad to generate them.

They are suitable for use with paper; even outside, if you live in a very dry climate.

[USSMissouri]

Cool stuff.