|MadSci Network: Astronomy|
Hey there, I realize that we've missed the eclipse, so hopefully you didn't use your grade 10 welding mask to view it. The sources I looked at (Sky an Telescope, July 1991, p. 80) recommended using at least a grade 12, and preferably a grade 14 visor (which lets through 1 out of every 370,000 photons striking the front surface. Any way you look at it, viewing an eclipse directly is not the safest route to go. Only one second of direct viewing of the sun can result in permanent damage. This is often heat damage caused by infrared radiation, which is why UV blocking sunglasses won't keep you safe while viewing an eclipse either. As I was saying, try to stick to projection methods of viewing such as mirrors or pinholes. But if you absolutely insist on viewing an eclipse directly, make sure you use a filter that blocks out nearly all visible light as well as infrared and UV radiation. Most eclipse glasses are made from aluminised Mylar or a black polymer. Back in the day, when film contained silver nitrate, you could view eclipses through exposed negatives, BUT THIS IS NO LONGER TRUE! Today's plastic films offer no infrared protection! For more info, check out this eclipse viewing site by clicking below. Good Luck, Tom Safe eclipse viewing
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