NavList:

Ken, you wrote:
"The lens in your eye will  only cause an increase in temperature of about
2°C on the retina, so the  actual damage caused by looking at the sun with
the naked eye is  photochemical. With a telescope, though, one can get much
higher  temperatures on the retina. Protein denaturation (cooking) occurs
at around  60°C and it would awfully surprising if you couldn't get that
with a  telescope."

Thanks. That makes sense, and it seems to be confirmed an  article in the BMJ
as follows:
"There are two main mechanisms of retinal  injury from solar radiation.
Thermal burn is caused by looking at the sun  through a telescope or through other
optical aids, which can cause a temperature  rise of 10-25°C in the retina.
But the most common form of solar retinopathy is  caused by looking at the sun
without eye protection. A retinal temperature rise  of as little as 4°C can
trigger photochemical injury to the retinal receptor  cells. The condition can
occur without pain and without being immediately  apparent."
Here's the rest of the  article:
http://bmj.bmjjournals.com/cgi/content/full/319/7208/469


-FER
42.0N  87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars


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