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How to Make a Reflecting Telescope

If you want to make a great science project with your kids, or with your class, nothing beats building your own telescope. There are two main kinds of telescopes; refracting and reflecting. You can make a refracting telescope easily enough, but nobody wants easy, so this article will show you how to make the much cooler reflecting telescope.

Things You'll Need

Cardboard Tubes of Various Sizes
Concave Mirror
1 Inch Sq. Mirror
Duck Tape
Hobby Knife
Glue

Instructions

- 1
  Get a concave mirror like the kind you can get at any hardware store. Figure out the focal length of the mirror. Do this by standing outside and focusing sunlight onto a flat surface facing you. Move closer or further away until the light forms a point. Measure the distance between the surface and the mirror. That's the focal length.
- 2
  Buy a piece of tube that is the diameter of the mirror. It should also be slightly longer than the focal length. Glue the mirror inside, with the reflective surface facing the other end. Use a sharpie to mark the tube 4 inches down from the mirror.
- 3
  Measure the width of a smaller tube, and where you marked the big tube, cut a hole that's the same size. Treating this hole as 12 o'clock, cut two more small holes at 9 and 3 o'clock. Then push a small dowel through these last two holes. Then glue a 1 inch square mirror onto the dowel. Then turn the dowel so the mirror tilts at 45 degrees.
- 4
  Cut another small tube open, roll a small magnifying glass inside it, and tape the tube back together tightly. This magnifying piece should now be slipped into the first smaller tube, and be loose enough to move up and down, but tight enough to stay in place without you holding it.
- 5
  Place this optical unit into the 12 o'clock hole. You should now be able to view things through the telescope.

Astronomy