NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Looking at the Sun through a telescope
From: Frank Reed CT
Date: 2006 Aug 6, 22:57 -0500
Red, you wrote:
"Well, assuming one can trust the BBC take a look at
http://news.bbc.co.uk/1/hi/sci/tech/specials/eclipse99/355066.stm
for actual photos of retinal damage from looking at the sun with the naked
eye."
First, bear in mind that that web page was created before the 1999 total
solar eclipse, and it was partly intended to scare people (not entirely
unreasonable in this case). You may want to read this article for a post-eclipse
assessment:
http://bmj.bmjjournals.com/cgi/content/full/319/7208/469
I enjoyed the little story in this article about the woman who thought the
eclipse had caused her face to turn yellow...
You also wrote:
"Now, do any of you gentlemen honestly think using a telescope or sextant can
REDUCE this type of damage?
If not, then the special case of using telescopes becomes a moot point.
I'm sure this list had this discussion a couple of years ago. What does it
really matter about the details, once one knows that LOOKING INTO THE SUN
MORE
THAN FLEETINGLY CAN DAMAGE YOUR EYES?"
The damage from eclipse observing is very different from the sort of damage
that one might worry about with a small sextant telescope, and I do think
there is more to the issue than you're seeing right now. The damage done during
eclipses apparently arises because the eye's blink response, which normally
causes us to avert our eyes from direct sunlight, is not activated by the smal
l portion of the Sun's disk exposed when the Sun is more than about 95%
occulted by the Moon. You can look at the Sun with no discomfort and the damage is
not apparent until hours later.
Looking at the Sun through a sextant telescope, that blink response will be
activated right away, but it may not be fast enough. It's not the same issue
as eclipse blindness.
-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
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From: Frank Reed CT
Date: 2006 Aug 6, 22:57 -0500
Red, you wrote:
"Well, assuming one can trust the BBC take a look at
http://news.bbc.co.uk/1/hi/sci/tech/specials/eclipse99/355066.stm
for actual photos of retinal damage from looking at the sun with the naked
eye."
First, bear in mind that that web page was created before the 1999 total
solar eclipse, and it was partly intended to scare people (not entirely
unreasonable in this case). You may want to read this article for a post-eclipse
assessment:
http://bmj.bmjjournals.com/cgi/content/full/319/7208/469
I enjoyed the little story in this article about the woman who thought the
eclipse had caused her face to turn yellow...
You also wrote:
"Now, do any of you gentlemen honestly think using a telescope or sextant can
REDUCE this type of damage?
If not, then the special case of using telescopes becomes a moot point.
I'm sure this list had this discussion a couple of years ago. What does it
really matter about the details, once one knows that LOOKING INTO THE SUN
MORE
THAN FLEETINGLY CAN DAMAGE YOUR EYES?"
The damage from eclipse observing is very different from the sort of damage
that one might worry about with a small sextant telescope, and I do think
there is more to the issue than you're seeing right now. The damage done during
eclipses apparently arises because the eye's blink response, which normally
causes us to avert our eyes from direct sunlight, is not activated by the smal
l portion of the Sun's disk exposed when the Sun is more than about 95%
occulted by the Moon. You can look at the Sun with no discomfort and the damage is
not apparent until hours later.
Looking at the Sun through a sextant telescope, that blink response will be
activated right away, but it may not be fast enough. It's not the same issue
as eclipse blindness.
-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---
