can the moon damage eyesight?

I know this may seem a bit extreme, but without a moon filter
the full moon is a very bright object through a telescope, I was wondering
if it could actully damage eyesight?, no where near the level of our sun
of course.

Simon

Simon wrote:

I know this may seem a bit extreme, but without a moon filter
the full moon is a very bright object through a telescope, I was wondering
if it could actully damage eyesight?, no where near the level of our sun
of course.

Simon

Short answer, no.
The Moon is not nearly bright enough to damage your eyesight.

--
Gareth Slee

Gareth Slee wrote:
Simon wrote:

I know this may seem a bit extreme, but without a moon filter
the full moon is a very bright object through a telescope, I was wondering
if it could actully damage eyesight?, no where near the level of our sun
of course.

Simon

Short answer, no.
The Moon is not nearly bright enough to damage your eyesight.

But it's bloody big enough though!

You don't want to get one of those in your eye.

"Simon" wrote in
:

I know this may seem a bit extreme, but without a moon filter
the full moon is a very bright object through a telescope, I was
wondering if it could actully damage eyesight?, no where near the level
of our sun of course.

Simon



It can be no worse than looking at a sunlit asphalt parking lot here on
earth. It can dazzle in the same why you would be dazzled exiting from a
dark room into full daylight. That will destroy your dark adapted vision
for a half hour or so.

Klazmon.

"Simon" wrote in message
...
I know this may seem a bit extreme, but without a moon filter
the full moon is a very bright object through a telescope, I was wondering
if it could actully damage eyesight?, no where near the level of our sun
of course.

Appended is a table of the relative brightness of common objects in
magnitudes (a log scale), magnitudes per arcsec squared (a log scale) and
the B scale (linear) used by photographers. The full Moon is only 1/5 (B-
200/1000) as bright as the daytime sky and is 0.0000025 ( B- 200/80000000)
as bright as the unfiltered Sun. When you apply telescopic or binocular
aperture (light grasp) and magnification, the two can interact usually to
make a dimmer image than what is seen with the naked-eye.

There is no probability that you will damage the eye looking at the full
Moon without the a filter, since it is dimmer than even looking at a blue
sky during daytime.

The full Moon's psychological annoying brightness is a testament to the
eye's ability to function well across such a range of brightnesses seen in
daylight and darknesses.

Sorry if the table doesn't translate well to a newsgroup text posting.

- Canopus56

Object category NELM MPSAS (Ba) B
Moon thin crescent -7.0 6.7 8
Moon wide crescent -7.8 5.9 16
Moon quarter phase terminator objects -8.5 5.2 32
Moon gibbous -9.3 4.4 70
Moon full -10.3 3.4 180
Moon earthshine -0.2 13.5 0.016
Moon partially eclipsed, expose bright side -9.0 4.7 50
Moon partially eclipsed, expose umbra and penumbra -3.2 10.5 0.25
Moon relatively light total eclipse -1.5 12.2 0.05
Moon relatively dark total eclipse 1.1 14.8 0.005
Comets (widely vary) 3.1 17 0.0006
Nebulae, bright (M42,M27,M57) 2.7 16.5 0.001
Nebulae, M57 Ring Neb. B=0.00006
Nebuale, NGC3587, Owl Neb. B= 0.000015
Nebulae, faint (California, Horsehead) 6.1 21 0.000016
Galaxies, bright cores 4.0 18 0.00025
Galaxies, nuclear bulge B=0.00004
Galaxies, inner arms B=0.000008
Galaxies, outer regions (underexpose) 6.1 21 0.000016
Galaxies, outer arms B=0.000004
Galaxies, faint B=0.000002
Sky daytime B=1000
Sunset, 10 minutes after B=120
Sunset, 30 minutes after B=0.93
Civil twilight B=0.46
Night, away from city lights, subject under full moon. B=0.3
Urban night sky B=0.002
Sky fog limit, typical city sky (NELM 4.5, Bortle Class 8) 2.2 16 0.0016
Sky fog limit, typical town sky (NELM 5.5, Bortle Class 6) 4.0 18 0.00025
Suburban night sky B=0.00015
Rural night sky B=0.00001
Darkest sky 6.6 21.986 B=0.000007
Sun (full disk, unfiltered, causes blindness) NELM=-10.8 B=80000000
Sun (full disk, unfiltered, causes blindness) B=10000000
Sun prominences, no filter B=100
Sun total eclipse - prominences and innermost corona, no filter MPSAS=4.8
B=48
Sun inner corona, no filter B=50
Sun middle corona, no filter B=5
Sun total eclipse - prominences and inner corona, 3° TFOV, no filter -6.2
7.5 4
Sun (full disk or partial eclipse with OD 6 (1/10^6) filter) -9.5 4.2 80
Sun (full disk or partial eclipse with OD 5 (1/10^5) filter) -12.0 1.7 800
Sun (full disk or partial eclipse with OD 4(1/10^4) filter) -14.5 -0.8 8000

NELM=Naked Eye Limiting Magnitude or apparent magnitude

Sources:

Berry, R & Burnell, J. 2005. 2d. Handbook of Astronomical Processing. (HAIP)
at p. 122. Willman-Bell. http://www.willbell.com/

Parker, Fred. 2005. The Ultimate Exposure Computer. (Webpage)
http://www.fredparker.com/ultexp1.htm#evfclux

Croswell, Ken. 2005. What are LV and EV?
http://www.kenrockwell.com/tech/ev.htm

Garstang, R. H. 1989. Night-sky brightness at observatories and sites.
1989PASP..101..306G
http://adsabs.harvard.edu/cgi-bin/np...ASP..101..306G

Garstang, R. H. 1989. The status and prospects for ground-based observatory
sites. 1989ARA&A..27...19G
http://adsabs.harvard.edu/cgi-bin/np...%26A..27...19G

Covington, M. 2ed. 2002. Appendix C. In Astrophotography for the Amateur.
Cambridge. ISBN 0-521-62740-0 http://www.covingtoninnovations.com/

Covington, M. 2ed. 2002. Appendix C. In Astrophotography for the Amateur.
Cambridge. ISBN 0-521-62740-0 http://www.covingtoninnovations.com/

Rogers, Mike. 2006. Implementation of Covington's Exposure Calculator. (Web
applet) http://www.rphotoz.com/astrophoto/expcalcs.html

Covington, M. 2005. Exposure Calculator. (Freeware - software)
http://www.covingtoninnovations.com/...astrosoft.html

Starzonia. 2005. Exposure Calculator. (Web applet)
http://www.starizona.com/ccd/calc_ideal.htm

In message , canopus56
writes
"Simon" wrote in message
...
I know this may seem a bit extreme, but without a moon filter
the full moon is a very bright object through a telescope, I was wondering
if it could actully damage eyesight?, no where near the level of our sun
of course.

Appended is a table of the relative brightness of common objects in
magnitudes (a log scale), magnitudes per arcsec squared (a log scale) and
the B scale (linear) used by photographers. The full Moon is only 1/5 (B-
200/1000) as bright as the daytime sky and is 0.0000025 ( B- 200/80000000)
as bright as the unfiltered Sun. When you apply telescopic or binocular
aperture (light grasp) and magnification, the two can interact usually to
make a dimmer image than what is seen with the naked-eye.

There is no probability that you will damage the eye looking at the full
Moon without the a filter, since it is dimmer than even looking at a blue
sky during daytime.

I'm obviously missing something, but if that was true wouldn't it appear
dark against the sky? (assuming you could see it at all)

Jonathan Silverlight
wrote:
since it is dimmer than even looking at a blue
sky during daytime.

I'm obviously missing something, but if that was true wouldn't it
appear dark against the sky? (assuming you could see it at all)

Yes, one of the things you are missing is the amazing adaptability of
the human visual system, only part of which is the eye, and most of
which is behind the eye. Another thing is that we can still see things
if they are not as bright as their backgrounds.

Try photographing the Moon in a daylight sky at different exposures. The
blue of the sky becomes visible at shorter exposures (or smaller
apertures) than does the Moon.

Best,
Stephen

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Jonathan Silverlight wrote:
In message , canopus56
writes
The full Moon is only 1/5 (B-
200/1000) as bright as the daytime sky and is 0.0000025 ( B- 200/80000000)
as bright as the unfiltered Sun.

I'm obviously missing something, but if that was true wouldn't it appear
dark against the sky? (assuming you could see it at all)

The full Moon is apparent when the Moon is 180 degrees from the Sun,
along the Sun, Earth line. The full Moon is opposite the Sun and does
not appear during the daytime.

I usually notice the Moon during the daytime when it is near the third
quarter. It is in the sky during the day and can be seen setting in
the west in the afternoon. At this point the Moon is more than 90
degrees from the Sun and the brightness of the sky - which is greater
near the zenith than at the horizon - does not overwhelm the Moon's
brightness.

Closer to new Moon, the Moon and Sun are nearly aligned on the
Earth-Sun line and the side of the Moon facing the Earth is not
reflecting sunlight. The side facing the Earth is dimmer relative to
the sky brightness as compared to the full Moon. It is also closer to
the Sun where sky brightness is greatest. At this time, atmospheric
scattering overwhelms the relative dimness of the Moon, even though the
Moon is 1/2 degree in diameter. A 1/2 degree is not really that large
- it is 1/2 the width of your index finger nail on your outstretched
arm. So, except for solar eclipses, you do not see the new Moon as a
black disk against the bright daytime sky - and even then it is against
the background of the brighter Sun.

The same phenomena occurs with the bright planets like Venus. Venus is
visible in the dawn light but is overwhelmed by the sky brightness as
the Sun rises. Nonetheless, a skilled amateur (because of the risk of
permanent vision loss from using a telescope while the Sun is up) can
view Venus during the daytime.

- Canopus56

In article ,
Simon wrote:
I know this may seem a bit extreme, but without a moon filter
the full moon is a very bright object through a telescope, I was wondering
if it could actully damage eyesight?, no where near the level of our sun
of course.

Telescopes don't generally make non-point objects brighter. They
collect a lot more light, but the magnification spreads it out. A
10cm scope is about 50 times wider than your pupil (less, when
dark-adapted), and a magnification of 50 will cancel this out.

On the other hand, the magnification means that more of your pupil is
illuminated, and small eye movements don't change which cells are
being illuminated (and heated). So looking at the sun will indeed do
far more damage through a telescope. But looking at something which
is harmless to stare at with the naked eye, such as the moon, won't be
much worse through the telescope.

-- Richard

On 24 Oct 2006 14:14:08 GMT, in uk.sci.astronomy ,
(Richard Tobin) wrote:

In article ,
Simon wrote:
I know this may seem a bit extreme, but without a moon filter
the full moon is a very bright object through a telescope, I was wondering
if it could actully damage eyesight?, no where near the level of our sun
of course.

Telescopes don't generally make non-point objects brighter. They
collect a lot more light, but the magnification spreads it out. A
10cm scope is about 50 times wider than your pupil (less, when
dark-adapted), and a magnification of 50 will cancel this out.

Euh. This is somewhat incorrect. The telescope gathers that light and
focuses it down to a disc slightly larger than your pupil. a cm or so
behind the eyepiece lens. This is why its dangerous to look at the sun
- 64 square inches of light concentrated into 1/16 square inch = quite
a lot of energy.
--
Mark McIntyre