How to Make a Pinhole Planetarium
A pinhole planetarium provides a small, portable light-up map of a constellation for little more than the cost of a pop can. To use the planetarium, just look through the peephole--the natural hole in the top of the pop can--toward a strong light. The light will shine in through the holes in the bottom of the can, creating an illuminated map of the constellation that the planetarium is for.
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Things You'll Need
- Empty pop can
- Blank paper
- Pen or pencil
- Scissors
- Wire brads
- Finishing nails
- Tape
- Hammer
Instructions
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Rinse your empty pop can to remain any soda residue, and let it drip dry.
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2
Download a Star Finder chart from the NASA Space Place or use any other star map to identify the constellation you’d like to create in your pinhole planetarium. Print off or photocopy the diagram or map of the constellation you’ve chosen.
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Place the pop can on the printed copy of the constellation map, pop-top facing up. If the bottom of the can covers the constellation entirely, you can proceed to the next step. If the constellation is larger than the bottom of the can, use a photocopier--or reproduce by hand--to shrink the constellation until it fits within a 2 1/2-inch diameter circle, which is the size of the pop can’s bottom.
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4
Trace around the bottom of the pop can, creating a circle around the constellation map. Cut this circle out.
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Poke a small hole in the map, over each star, with a nail. You can use wire brads to poke out smaller stars and finishing nails to poke out larger stars.
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Tape the paper disc, with poked-out holes, over the bottom of the pop can. Make sure the printed side of the disc--the side with the ink and traced circle on it--faces toward the pop can.
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Use the nails to poke holes through the paper again, but this time tap each nail gently with a hammer to make a hole in the pop can, too. Then pull the nail out and repeat to make holes for all the other “stars.”
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Remove the paper from the pop can and discard or store for later re-use. Your pinhole planetarium is complete.
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Tips & Warnings
You could also do this project with any plastic container with a tight-fitting lid; just poke holes in the bottom of the container for the stars, as directed above, then poke or cut a large hole in the lid of the container to use as a peephole. Place the lid on the container and look toward a bright light to use the planetarium.
If you make planetariums for more than one constellation, keep them straight by placing a label on the side of each can with the name of the constellation it represents. Or, leave the cans unlabeled and challenge students or friends to identify the constellations inside.
Don't use the planetarium to look straight at the sun; it doesn't provide enough protection from such bright light.
