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Tuesday, March 21, 2006

Solar Eclipse 29 March 2006



ECLIPSE VIEWING SAFETY!

A Solar Eclipse is a truly, truly wonderful phenomena. But one
MUST OBSERVE IT CAREFULLY!

SEVERE eye damage can result if the sun is viewed improperly at any time!!

Safe Methods of Viewing

METHOD 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. Make sure that the glasses have the "CE" certification 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.

METHOD 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).

METHOD 3) Welder's Glass

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 7's 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).

METHOD 4) Telescopic Projection

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!

(a)Sunglasses (b)Multiple Sunglasses

(c)Mylar Balloons (d) Mylar Food Wrappers (Pop Tart Bags, etc.)

(e) Smoked Glass (f) X-Ray Film

(g) Film Negatives (h) CD's or CD-ROM's

(i) Stacked Welder's Glass

(j) Stacked Welder's Glass

(k) Liquid Filters

(l) Eyepiece Solar Filters

(m) Eclipse Glasses and Telescopes Together

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This is science !

When you are speaking to technically illiterate people you must resort to the plausible falsehood instead of the difficult truth.

Photos of Comet Mcnaught !
Astro-photographer? Send your photos to pics@exploreuniverse.com and have them featured on this blog with your name. Comet Mcnaught : Pictures taken with Nikon D100 on 19/1/07 from Manning Point, northern NSW, Australia by Mr. Peter Enright.
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