Make a telescope

If you want a better view of birds, treetops, or even the night sky, you and your family can build your own simple telescope. Use this make-it-yourself device to explore the world, then check out these tips to keep track of what you see.

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You Will Need

• Two empty paper towel tubes
• Scissors
• Masking tape
• Paint, markers, or crayons to decorate your telescope 
• 2 convex lenses. If your parents have old reading glasses they aren’t using, ask them to help you remove the lenses from the frame. Make sure the glasses are reading glasses and not glasses for helping to see things far away. If you don’t have old reading glasses to use, you can ask your parents to order convex lenses online.

Step 1

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Choose one of your tubes to be the inner tube. Cut that tube lengthwise (all the way up the side). Wrap one edge of the cut side slightly over the other edge and hold it in place with one hand.

Step 2

Insert the cut tube into the other paper towel tube. Let go of the inner tube so that it can expand inside the outer tube. If the inner tube is not sliding smoothly,remove it and wrap the edge slightly tighter. Then reinsert the inner tube into the other paper towel tube until it is just right.

Step 3

Using masking tape, secure one of the lenses to the outer edge of the inner tube. The curve of the lens should be facing the inside of the tube.

Step 4

Then secure the second lens to the outer edge of the second tube, with the curve of the lens pointing outside of the tube. It’s OK if your lenses are bigger than the tube. Try to only tape around the rim of the lenses so you don’t cover too much.

Step 5

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Place your eye against the lens of the inner tube. Aim your telescope at faraway animals or tall treetops (but never use a telescope to look at the sun). Focus by sliding the inner tube in and out until the image becomes clear.

WHAT’S GOING ON?

Your telescope is a “refracting telescope,” because it uses lenses to help gather more light than your eye could possibly do on its own. The scope uses two lenses to bend light, which makes an object appear closer than it really is. The size of the image produced by the telescope depends on the curvature of the lenses. Lenses with different curvatures will change the magnification of the telescope.

ADAPTED FROM THE NAT GEO KIDS BOOK MAKE THIS! BY ELLA SCHWARTZ