About ten years ago I was really into astronomy as a hobby. I don’t do very much stargazing these days, but it is a wonderful hobby that I will probably invest more time in later in life.

Since I am a Christian, I was especially interested in studying Ancient Hebrew Astronomy. I found 3 excellent books on the subject that I used for most of my study:

• God’s Voice in the Stars: Zodiac Signs & Bible Truth – Kenneth C. Fleming
• The Witness of the Stars – E. W. Bullinger
• The Gospel in the Stars – by Joseph A. Seiss

There are more books available, but these are the ones that I used primarily.

At that same time, I was teaching a 5th-grade Sunday School class. I wanted to teach them these fascinating stories from Hebrew history using the stars. The only problem was that the class met at 10:oo AM on Sunday morning instead of 10:oo PM.

My wife had given me a toy planetarium for Christmas the previous year. I was going to use this in the classroom, but everything got all skewed when it projected on the flat ceiling and walls. I really needed a dome to use it properly.

I couldn’t find a reasonably priced dome that would fit my needs, so I decided to create my own. There were only a few students in the class, so it didn’t need to be very big. I thought that a 6-foot diameter would work well. I had access to some scrap cardboard from work that was white on one side, so I decided to use this as my main material. I would cut out 64 cardboard panels and tape them together to make my dome. It would be made in 4 sections that could collapse and nest together for easy storage. It would have extra tape on the sides of each section and I would use binder clips to hold the sections together.

I had a pretty good idea how to make it, but I didn’t have any idea about what the dimensions on each cardboard piece should be. I hadn’t used trigonometry since I was in high school, but I knew that was the tool I needed. I checked out a trigonometry book from the library and set about to teach myself trigonometry all over again. Although I must admit that I’ve probably forgotten most of it again now, at that time, I’m confident that I understood it much better than when I was in high school because I had a problem to solve with it.

I wrote some formulas that would help me determine the dimensions for each trapezoid, and the dimensions for the triangles near the top. I put these in a paper I called Formulae for Panelized Hemisphere Construction (PDF). It’s been 9 years since I wrote that paper, and I’ve never shared it with anyone until now. If you have ever wanted to make your own panelized dome, I hope this helps. Because it has been so long, I doubt that I can answer many questions. If you have any comments, or you actually use this information for something, I would appreciate it if you would let me know in the comments.

Here are a few pictures of the completed dome in use:

This is the view of the fully assembled dome as it sat in the corner of our classroom.
You can see the panels clearly, and you can even see the binder clips that held the sections together.

 

The whole dome rested on a wooden frame made from inexpensive 1×2 lumber.
The church was Bethany Baptist Church in Thomasville, NC, so I called it The Bethany Planetarium.

 

You can see the projector and the dome in this view. I set the projector on a speaker cabinet
which brought it up to the perfect height.

 

I didn’t have any way to project other information on the dome, so I printed the constellation
charts from on of my books, blew them up, taped them together, and then taped that to
the support frame. All the students were on one side and they could see this. I used a
laser pointer to point out stars in the picture and on the dome.

 

This shot shows the projector and the zenith of the dome.
Everything fit together quite nicely.

 

I couldn’t find any pictures of the collapsed dome,
but I did find one picture that had it sitting in the corner.
The four sections would nest, and and fold up to fit in a small area.

The planetarium sat unused in the corner of my home office for years. A few years ago, I donated it to the Forsyth Astronomical Society. I’m not sure how they are using it today, but hopefully it is still helping to educate some people on the beauty of the night sky.

If you live in a location with a lot of light pollution, building a home planetarium can be a great project for you and your children, and a great way to use that toy star theater the way it was meant to be used.