On Monday, August 21, 2017, North Americans will have the opportunity to view nature’s greatest show — a total solar eclipse. This total eclipse will be the first in nearly four decades that will be visible so close to home. The “path of totality” will sweep only over the United States and no other country for the very first time, leading some to refer to this upcoming event as “The Great American Eclipse.”
Whenever a solar eclipse is due to occur, there are usually dire warnings telling people that there is no safe way to view it, and the best thing to do is watch it on television. Television, however, is no substitute for the real thing. This is not to say, however, that you should not take precautions. Staring at the Sun with unprotected eyes or inadequate filters during the partial stages of an eclipse can cause severe retinal damage or blindness.
View it Safely!
Whether or not you’re in the path of totality, you need to take precautions when looking at an eclipse of the Sun. Here are a few ideas.
Make A Pinhole Reflector
A safe way to view the Sun during the eclipse is by constructing a “pinhole reflector.” All you need do is use a flat household mirror to reflect sunlight onto a surface or screen which can be the side of a house or building.
- Dark paper
- Household mirror (The mirror must be a flat (plane) mirror, not a convex one that gives a magnified view when you look into it)
- Scissors and tape
- A blank wall to reflect onto
Step 1. Cut a round, dime-sized hole in a dark colored piece of paper. See Fig. A.
Step 2. Place paper over the mirror. Secure it with tape if you need to. See Fig. B.
Step 3. Head outside, and position the mirror so you are able to reflect a spot of sunlight onto a nearby blank wall or screen. The image will be one inch across for every 9 feet from the mirror.
You might wonder what would happen if you didn’t cover the mirror with a hole punched through dark paper. The answer is that you would get a much brighter, but much fuzzier image of the Sun. The dime-sized hole makes the image sharper, but dimmer.
IMPORTANT: If you are projecting the Sun’s image with a mirror, do not let anyone look at the Sun in the mirror!
You can also produce eclipse images by letting sunlight shine through the lattices of your fingers as well as any other small openings such as those in a straw hat or trees and bushes.
Even indoors, closed venetian blinds in a window facing south can produce row upon row of solar crescents on the wall or on the floor.
You can even make a pinhole projector using a cereal box!
When viewing the solar eclipse, DO NOT USE regular sunglasses, photographic filters, old color film negatives, or smoked glass to watch the Sun. You CAN, however, use a rectangular piece of welder’s glass, designated as “shade 14,” which can be bought at a welder’s supply shop in sizes that will cover both eyes. The Sun appears green when viewed through this type of filter and can be viewed for short periods. Do not use welder’s filters with a shade number lower than 14. Shade 13 is on the borderline of what is considered to be safe and using welding filters of 12 or lower is downright risky, if not dangerous. Do not use welder’s glass placed up against the eyepiece of a telescope—it will crack.