For Solar Viewing, Make Your Own--
Pin-Hole Projector

In order to view a solar eclipse safely (or look for sunspots!), you will need either an astronomical grade solar filter, or a good mechanical means to view the sun.

Noooo....eclipse light is not different from any other light that we get from the sun--neither solar eclipse light nor lunar eclipse light.   (Solar eclipse light is just normal sunlight that has been partially blocked by the fact that the moon has gotten between Earth and the sun.  Lunar eclipse light is simply sunlight that has come from the sun, gone over the Earth's shoulders, as it were, and landed on the reflective surface of the moon where it is bounced back to Earth as if by a mirror). 

There are rumors that spread every time there is an eclipse...especially a solar eclipse...that the light from an eclipse is poisonous.   If you know that that is not true, you might laugh, but there are many people who actually believe that eclipse light can cause you to go insane, go blind, or get cancer--immediately.

While we don't make fun of people's fears (some have their basis in a smidgen of truth), we do caution you never to view a solar eclipse without proper solar filters or other means, such as the pin-hole projector.  Light from the sun can damage the retina if you stare at it too long, and during a solar eclipse, when the sun is partially covered by the moon, people do tend to stare a lot.  We also know that you shouldn't be outside without sunblock with at least an SPF rating of 15 at any time...an eclipse is not an exception to that rule.  Skin cancers and cataracts may be formed when the skin or eyes are repeatedly exposed...unprotected...to the sun. A lot of good things can be deadly when overindulged in to the extreme...even water can give you "water poisoning" if you drink so much that your body's salt/water balance is greatly disrupted. Likewise, overexposure to the sun's rays is not good for you.

Therefore, the easiest way to view a solar eclipse is by using a method that won't compromise you physically in any manner. What you need is a pin-hole projector.

You can easily make a pin-hole projector; you will need the following materials:

The Pin-Hole Projector

The easiest thing to use for pin-hole projection will be a regular cardboard box, at least two feet in length. The width doesn't matter.

First, you cut a hole about an inch in diameter in one side. Then, on the far side (about 2 feet distant), you paste up a sheet of white paper or card stock to the inside of the box. If you use card stock, place the sheet shiny side down--you want the dull side facing you.

Over the inch-wide hole, tape a piece of paper or an index card. Punch a small hole in the center of the piece of paper with a sewing needle, pin or other sharp object. The hole doesn't have to be any larger than a pin-hole (hence, the name...pin-hole projector!).

That's it!

Using a Pin-Hole Projector

The box may be a bit unwieldy for younger children, but a nine-year old can surely manage it easily.

First, put on sunblock that has an SPF number of 15 or higher, and preferably, a hat with a wide brim, like a cowboy hat or a garden hat. You will be keeping your back to the sun, but your arms, possibly your ears, and the back of your neck will still be exposed to the sun's rays. Since we know that frequent exposure to the sun's rays can cause skin cancers, it is only prudent that we protect ourselves.

The best position for using the projector is...sitting...preferably on the ground. The sun itself will be at your back. The box end with the hole will be facing the sun, and the inside of the box's farther end with the white sheet will be in front of you...probably resting on the ground. The box itself will be upside down with the open top next to the ground so that the shade becomes a darkened theater for the projected image.

Maneuver (this may take some time....be patient!) the box until the sun strikes the pin-hole in a direct line, causing an image to appear on the white paper inside the box. The box sides and top add shade (contrast) to make the image stand out better. The image itself will appear as a sharp, round circle, about a half-inch across. If the box is bigger, the image will be larger, but dimmer.

You might note that if you have clouds passing over the face of the sun, you will find that the image is truly inverted...clouds that move from your left to your right over the face of the sun as you view the sky will appear to move from right to left over the face of the sun as you view the sun's image on the white sheet of paper.

You might think that the circular shape of the sun is produced by the hole...not so! The hole could be rectangular in shape, and the sun would still appear to be round because it is round!

If you are viewing an eclipse of the sun, when the moon moves in front of the sun , it will take ten minutes or so after the eclipse actually begins for you to be able to notice that the moon has taken a "bite" out of the edge of the sun's disc.  Near the center line of the eclipse path, the moon will cover most of the sun, and the sun's image will appear on the paper to be a bright crescent. (The eclipse path is the geographical line along which the moon's shadow passes over the earth...it doesn't pass over everyone at the same time.)

If you don't want to go to the trouble of hacking up a box and making a pin-hole projector to see an eclipse, you may want to go outside and find a nice tree with lacy foliage. Sit under the tree, and during the deeper phases of the eclipse, if you look on the ground, you will be surrounded by hundreds of solar crescents dancing with every breeze.   It is a really neat experience!


An Alternate Method of Projection...the Pin-Hole Mirror

You will need a flat mirror (not a magnifying mirror). Mask off all but about a half-inch wide square in the center of the mirror. Masking tape is the easiest masking substance, applied only to the front of the mirror--although, you may want to use paper...especially on the back of the mirror, if you want to protect the back surface of the mirror from accidental tape peeling.

On a bright, sunny day, reflect the sun's image onto a smooth light-colored flat surface that is in the shade. You will have to be facing the sun, but you won't have to look directly at it...you can see the light image reflecting from the mirror, and all you have to do is manipulate the mirror until the bright light hits the "screen" that you have set up.

Although the hole may be square, the image will be round, as seen from at least 20-30 feet away. The greater the distance from the mirror to the screen, the larger the image, but the fainter it is. Twenty feet is about optimum for this kind of observation.

To hold the mirror steady, tape it to a camera tripod, or plant it in modeling clay.

Watch for a few minutes as the sun's image moves. It crawls across the "screen" because the Earth is turning eastward, making the sun appear to head West.

Again, the partial phases of eclipses show up well. Use a whole series of mirrors to project your own patterns on the screen. If you mask off several holes on the same mirror, you will have that many images in that pattern on the screen.

Experiment, and have fun!!


An inexpensive, pre-constructed  Solar Image Projector is available from Draco Productions.


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