[OT] Looking at the sun - Safe distance?

"Henry Spencer" wrote in message
...
In article ,
Bruce Palmer wrote:
On some afternoons, depending on clouds and atmospheric dust, the sun
looks like a giant orange ball that you can actually look at without eye
damage as it sets...

A note of caution: safely low visible-light intensity doesn't necessarily
equate to safely low UV and IR intensity (especially the latter, which has
a tendency to penetrate clouds etc. better than visible light). Your eye
is not a reliable guide to what's eye-safe.

This is in fact my understanding of exactly why total eclipses are so
dangerous. You're not expecting the still high UV/IR does and your pupils
are more dilated than usual, allowing more light in.


(I'll admit to having yielded to the temptation to look in such
situations,
especially when there were naked-eye sunspot groups visible... but only in
brief glances, never looking steadily.)

So, build a shadow box. An old shoe-box works great. I keep mine around
for eclipses. Should scale it up so I can watch sunspots.


--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

"Greg D. Moore (Strider)" wrote in message
...

"Henry Spencer" wrote in message
...
In article ,
Bruce Palmer wrote:
On some afternoons, depending on clouds and atmospheric dust, the sun
looks like a giant orange ball that you can actually look at without
eye
damage as it sets...

A note of caution: safely low visible-light intensity doesn't
necessarily
equate to safely low UV and IR intensity (especially the latter, which
has
a tendency to penetrate clouds etc. better than visible light). Your
eye
is not a reliable guide to what's eye-safe.

This is in fact my understanding of exactly why total eclipses are so
dangerous. You're not expecting the still high UV/IR does and your pupils
are more dilated than usual, allowing more light in.


(I'll admit to having yielded to the temptation to look in such
situations,
especially when there were naked-eye sunspot groups visible... but only
in
brief glances, never looking steadily.)

So, build a shadow box. An old shoe-box works great. I keep mine around
for eclipses. Should scale it up so I can watch sunspots.

I used a colander from the kitchen, and I got dozens of little crescents on
the wall last time (4-12-2002)

On Mon, 5 Jan 2004, Neil Gerace wrote:

I used a colander from the kitchen, and I got dozens of little crescents on
the wall last time (4-12-2002)

Next time, try saltines as well.

The only optical imaging system you can eat after the eclipse is over.

--
Bill Higgins | They can have my World Almanac
Fermilab | when they pry it from my cold, dead fingers.
Internet: | Or when next year's edition comes out, whichever is first.
| --Lois A. Fundis

On Mon, 5 Jan 2004 14:21:10 -0600, Bill Higgins
wrote:

Next time, try saltines as well.

....****, when I did this in High School, everyone thought I was nuts.
Good to see someone else thought of that one as well :-)

OM

--

"No ******* ever won a war by dying for | http://www.io.com/~o_m
his country. He won it by making the other | Sergeant-At-Arms
poor dumb ******* die for his country." | Human O-Ring Society

- General George S. Patton, Jr

I was reading in the bathroom when I ran across an item written by
"Greg D. Moore \(Strider\)" on Mon, 05 Jan 2004
04:41:22 GMT, which said:

So, build a shadow box. An old shoe-box works great. I keep mine around
for eclipses. Should scale it up so I can watch sunspots.

For a few bucks you can get a mylar-like sheet of Baader Solar Filter
material. I used some to make a filter for my telescope and looked at
the sun directly, rather than by projection. Had to give it up,
though, since the telescope was a reflector and I was getting
sunburned over only the left side of my face.


-------------
Beady's 11th Law of Social Harmonics: "Your spouse is precisely the kind of person someone like you would choose to marry."

"John Beaderstadt" wrote in message
...
I was getting
sunburned over only the left side of my face.

That happened to me once, but it was after a champagne breakfast at uni.

On Mon, 05 Jan 2004 09:37:54 GMT, John Beaderstadt
wrote:

I was getting sunburned over only the left side of my face.

....Then quit following those UFOs with the window down :-P\

OM

--

"No ******* ever won a war by dying for | http://www.io.com/~o_m
his country. He won it by making the other | Sergeant-At-Arms
poor dumb ******* die for his country." | Human O-Ring Society

- General George S. Patton, Jr

"OM" om@our_blessed_lady_mary_of_the_holy_NASA_researc h_facility.org wrote
in message ...
On Mon, 05 Jan 2004 09:37:54 GMT, John Beaderstadt
wrote:

I was getting sunburned over only the left side of my face.

...Then quit following those UFOs with the window down :-P\

Funny you'd mention that. I just got that on DVD and watched it like a week
ago.



OM

--

"No ******* ever won a war by dying for | http://www.io.com/~o_m
his country. He won it by making the other | Sergeant-At-Arms
poor dumb ******* die for his country." | Human O-Ring Society

- General George S. Patton, Jr

In article ,
Greg D. Moore \(Strider\) wrote:
A note of caution: safely low visible-light intensity doesn't necessarily
equate to safely low UV and IR intensity (especially the latter...

This is in fact my understanding of exactly why total eclipses are so
dangerous. You're not expecting the still high UV/IR does and your pupils
are more dilated than usual, allowing more light in.

If memory serves, total eclipses are safe for naked-eye viewing *during*
*totality*. But caution has to be exercised during the partial phases
before and after totality.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

Henry Spencer wrote:


If memory serves, total eclipses are safe for naked-eye viewing *during*
*totality*. But caution has to be exercised during the partial phases
before and after totality.

I'm pretty sure the corona's UV emissions can damage the eye even at
totality; I know my eyes hurt after I looked at a total eclipse for a
minute or two (and anyone who doesn't think that they are also going to
look at it during totality is fooling themselves- if there was a cage
with a tarpaulin over it that said "Warning! Medusa having sex with a
Basilisk! DO NOT LOOK!" around 95% of people would promptly take a peek
under that tarpaulin inside of ten seconds.)

Pat