Solar Viewing and Eclipses

A solar eclipse is a truly, truly wonderful thing. But one must observe it carefully!

Myths About Solar Eclipses

1. The Sun is safe to look at during a solar eclipse.
   Absolutely not. The Sun is a ball of exploding hydrogen 1,000,000 times larger than planet Earth. Its surface temperature is 10,000 °F. A permanent image of the Sun can be burned onto the back of one's eye, destroying the rods and cones. Staring directly at the Sun can cause damage to your eyes even if one does not feel any pain. If the sun is low on the horizon or obscured by clouds it may not seem very bright, but the dangerous UV rays can still cause damage even though one feels no discomfort. Sometimes the damage will not become apparent until many years later. Be careful when trying to view the Sun at any time!
2. The Sun is more dangerous to look at during a solar eclipse.
   Yes and no. During a solar eclipse, the Sun is no more dangerous to observe. there are no special "eclipse rays" coming off of it which will damage your eyes very quickly.
   
   People sometimes report silly fears about an eclipse. One woman called her local planetarium wanting to know if the eclipse was over – because she wanted to let her dog out of the closet. This illustrates the principle difference between people and animals. An animal will not stare at the Sun until it goes blind. Others have reported that local schools required students to go to great lengths to avoid the "eclipse rays." Some children were required to look at the ground and place their hands over their eyes while walking out to their buses at the end of the day.
   
   Having said that, keep in mind that during a solar eclipse the Sun is no less dangerous either. Viewing the direct, unfiltered rays of the Sun can cause permanent eye damage even if only a tiny portion of the solar disk is visible. Some people report eye damage after an eclipse because they viewed the sun unsafely, not because their eyes were zapped by the "eclipse rays."
3. It is never safe to view the Sun
   Not true. One can view the Sun safely and comfortably if one knows what one is doing. Read on to find out how.
   
   This myth is propagated by well-meaning but misguided people who allow fear to dictate what they do. There are those who will say that no filter is safe, no method of viewing the Sun should be allowed.
   
   This, of course, is not true.
   
   During solar eclipses many schools keep their students indoors and away from the windows "to protect their eyes." Fear of eye damage should a child ignore warnings and instructions is reasonable. However, these fears should also not keep a school from carrying out its educational mission. By educating the children properly a once-in-a-lifetime event can be viewed, and everyone can learn from it.
   
   The real problem with this attitude is that it can lead to exactly the sort of eye damage that the concerned people are trying to avoid. During eclipses, people will try to observe the sun. The question is, "Will they do it safely or not?" If we educate everyone and provide safe means to view the eclipse, the vision of thousands (or millions) of people will be protected.

Safe Methods of Viewing

1. Eclipse Glasses
   This is the most affordable method. Eclipse glasses are very inexpensive and can be found many places. Just be sure to buy them well before the eclipse because they will be very hard to come by a day or two before. Expect to pay $3.00 - $5.00 for the glasses. Make sure that the glasses have the "CE" label on them.
   
   Eclipse glasses usually consist of a cardboard frame holding two pieces of filtering material where the glass would be in normal sunglasses. The filters remove 99.99% of the Sun's visible light and 100% of the harmful UV. There are now two types of eclipse glasses. The older type has filters made of aluminized Mylar. The newer type uses black polymer lenses. Both will give good protection, but the black polymer type is better all around. They show a more natural color and can be used to look at sunspots any time the Sun is visible. They are more expensive than the Mylar glasses, but well worth the price.
   
   Always check the glasses carefully before each use for pinholes. If you find any, cut the glasses up with scissors and throw them away. 
2. Special Telescope Filters
   These filters fit over the front end of a telescope. Again, they filter out most of the Sun's light. The advantage with this method is that one can see a magnified image of the Sun, with sunspots, granulation, speckles, and other features. The disadvantage is that the filters are more expensive (plus one needs a telescope).
   
   Do not ever use older "eyepiece" solar filters! These were made many years ago to fit over the eyepiece of the telescope. The problem with them was that the intense heat of the focused Sun's rays bore down directly on the filter – and they tended to crack. If one is looking through the eyepiece at the time the filter cracks, one will never see anything out of that eye ever again. If you ever find one of these older eyepiece solar filters, please smash it with a hammer so that it may never harm anyone!
   
   As with the glasses, always check your filter for pinholes before use.
3. Welder's Glass
   Welding glass is used to protect welders from eye damage. The potential damage does not come from hot sparks hitting the eye (although that is a possibility). Rather, the glass prevents the light from the very hot arc from burning an image of itself permanently onto the back of the eye.
   
   Be careful that you use the right kind of glass! Welder's glass is numbered from 1 to 14 with 14 being the darkest. It is only number 14 glass that is dark enough for solar viewing! And no stacking! A pair of number 7s or a 10 and a 4 together do not have the same protection as a single piece of number 14 (see unsafe methods for more details).
4. Pinhole Projection
   The humble "pinhole camera" (or "camera obscura") is an easy, safe, and effective way to view the Sun during an eclipse. Unfortunately, the image of the Sun can be small, dim, and disappointing to some. Still, when the choice is either this or some unsafe method, one should by all means use this.
5. Telescopic Projection
   Telescopic projection is my personal favorite way to observe the Sun. One can get a nice, large, bright image visible to several people at the same time. It requires no special equipment beyond the telescope itself and some sort of flat screen. However: It can be very dangerous unless one knows exactly how to do it properly! Not only can it cause severe and permanent eye damage, but it can also easily set things on fire. Use caution when following these instructions!

Unsafe Methods of Viewing

Keep in mind that this is by no means an exhaustive list. People have historically been very clever in coming up with stupid ways to observe the Sun. In general, when you're considering whether or not a particular method is safe, ask yourself these questions:

• "Is this method I'm using specifically designed for solar viewing?"
• "Do I know exactly what I'm doing?"

If the answer to either of these questions is "no," then for your vision's sake, don't try it!

1. Sunglasses
2. Multiple Sunglasses
3. Mylar Balloons
4. Mylar Food Wrappers (Pop Tart Bags, etc.)
5. Smoked Glass
6. X-Ray Film
7. Film Negatives
8. CDs or CD-ROMs
9. Stacked Welder's Glass
10. Liquid Filters (Coffee, Sun tea, etc.)
11. Eyepiece Solar Filters
12. Eclipse Glasses and Telescopes Together

Where to Find Solar Filters

Several companies manufacture filters for naked eye and telescopic viewing of the Sun.

Eclipse Safety Summery

There are a few simple do's and don'ts with regard to any solar eclipse. Although they may be simple, they must be strictly adhered to in order to preserve your vision!

Do!

• Use specially made eclipse viewing glasses.
• Observe the eclipse with a pinhole viewing box (download instructions now!)
• Use number 14 welder's glass
• Use only solar filters specifically designed for viewing the Sun!
• Let your children see this spectacular event!

Don't!

• Put on the eclipse glasses and then look through binoculars or a telescope.
• Try observing the eclipse by looking through home-made filters of any kind! This includes (but is not limited to) pop-tart wrappers, CDs, exposed film, smoked glass, Mylar balloons, or old x-ray photos. These methods are unsafe!
• Try stacking pieces of welder's glass so the number ratings add up to 14 (the rating scale is not linear!) Two pieces of number 7 glass do not give the same protection as a single piece of number 14!
• Use any sort of item as a solar filter if it was not specifically designed for that use!