How to Make a Pinhole Projector to View the Eclipse Safely

There are safe ways to view the solar eclipse, even if you can’t find eclipse eyewear. The simplest requires only a long box (at least six feet long), a piece of aluminum foil, a pin, and a sheet of white paper.

The length of the box is important: the longer the box, the bigger your image of the sun will be. To estimate how big the image will be, multiply the length of the box by 0.01. For example, if your box is six feet (72 inches) long, your solar image will be 72 x 0.01 = 0.72 inches in diameter, or about ¾ inch.

1. Find or make a long box or tube. If you can’t find a long tube, you can tape together two or more shorter ones. (Two triangular shipping tubes, taped together, make a good solar viewer.) Cut out the cardboard at one end of each tube and tape those ends together with duct tape, so that light can travel the length of the tube.

2. Cut a one-inch hole in the center of one end of the box. Tape a piece of foil over the hole, then poke a small hole in the foil with a pin.

3. At the other end of the tube, cut a good-sized viewing hole in the side of the box. Put a piece of white paper at the end of the box, right inside the viewing hole. This is the screen where your projected Sun will appear.

To use your viewer, point the pinhole end of the box right at the Sun. To aim it, move it around until you see a round spot of light on the paper at the other end—that’s your pinhole image of the Sun! If you have trouble aiming your viewer, look at the shadow of the box on the ground. Move it until the shadow is as small as possible—that is, until it looks like the end of the box, and the sides are not casting a shadow.

Do not look through the pinhole at the Sun! Look only at the image on the paper.