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chrlzs
2011-May-16, 10:06 AM
I was a bit surprised to hear a comment on a thread that you couldn't read by moonlight... Puzzled, I then googled a little, and according to NASA (http://science.nasa.gov/science-news/science-at-nasa/2006/28sep_strangemoonlight/), most people can't. However, I find it very easy - am I one of those endowed with extra cones/rods, or is it my ... superpower? :D

To prove it in an interesting way (well, to myself, anyway), I just went out beneath the current 98% full moon, took about 3 minutes to allow my eyes to begin night adapting (ie *not* looking at the Moon!), and could then *very* easily read a moon-only-illuminated newspaper at all text sizes. The newspaper I was reading had the headlines "All US Goes Wild - Apollo Splash Splurge", and is dated 23 July 1969, from Melbourne Australia. (Yes, it's a treasured possession!)

So - am I that unusual? Who else on Baut can easily read by moonlight?

PS - I'm trying out the poll system - forgive me if this doesn't work... and if this isn't on topic enough, feel fee to move it to OTB, mods.

Perikles
2011-May-16, 10:22 AM
I read once about a German scholar, whose name and date I forget, who was known to study by moonlight because he was so poor he couldn't afford candles, and eventually went blind. Google doesn't help here - what an annoying name for a sonata.

I did find references to map-reading by moonlight during WWII

galacsi
2011-May-16, 10:24 AM
I lied , it was true 30 years ago !

Ronald Brak
2011-May-16, 10:47 AM
I have tried it and the answer is, "Not really."

astromark
2011-May-16, 10:59 AM
I am he that mentioned this... and I did so because the human eye has limitations...
In the darkness that is the 'Ward Observatory', where eyes are dark adjusted... for more than a hour...
On a viewing night of a full moon. ( which we had not looked at yet...)
Open the star catalogue we did... Oh!.. A book of times and declination and inclinations of objects in the sky.
Without turning on the red light we ( that's five fellow astronomers ) were amazed that none of us could read any of it.
The print is as clear as black on white can be and is of good size... but not one of five could see any recognisable text.
Yet we could see our moon shadow and have even seen a moon rainbow... but thats another story.

baskerbosse
2011-May-16, 12:50 PM
How convenient! The moon is out right now and nearly full. Išl give it a go..

baskerbosse
2011-May-16, 12:55 PM
Yep!

Easily, with not much dark adaptation. Nearly full moon straight overhead.
Ordinary newspaper text.

Peter

Cobra1597
2011-May-16, 01:21 PM
On a full moon night, sure, pretty easily. I try not to make a habit of it, it isn't very good for your eyes.

Ivan Viehoff
2011-May-16, 01:54 PM
Like the sun, the brightness of the moon depends how high in the sky it is, and how clear the air is, and even how much air there is - at high altitude the light travels through less of it to get to you for a given angle of the moon. Also probably the reflectiveness of the surrounding land (eg, covered in snow) would make a difference. And the brightness of the moon also depends upon its phase. So many variables, so much variation in the brightness of moonlight.

So camping at high altitude in Bolivia, ie at low latitude, under a near full moon high in the sky, with less air and low atmospheric moisture to attenuate the moonlight, I could go about most of my camping business in the darkness, provided I kept out of any shadow. I could not do these things under moonlight in Britain, except perhaps on rare occasions. (At high latitudes, like the sun, you never get the moon very high in the sky, and our British moistness is such that our air is rarely very optically clear. So in Britain you would probably need a winter full moon - highest ones come in winter - on a frosty night, preferably with snow lying, that would perhaps be about as bright.) I think I could make out text under that Bolivian moon, but not comfortably enough to want to read under it for any length of time. Besides, at highest altitudes it was freezing cold on clear nights, and at ones warm enough to sit out for a bit, there were biting insects. So I needed to retreat "indoors" as soon as I could.

korjik
2011-May-16, 06:07 PM
I barely could when I was young. Not a chance anymore tho.

KaiYeves
2011-May-16, 07:29 PM
I can read, but it depends on how much moonlight there is and now big the text is.

AstroRockHunter
2011-May-16, 08:16 PM
I said 'Yes, but small text is quite difficult', but that was only because that I (with my aged eyes) have a hard time reading small text in broad daylight.

baskerbosse
2011-May-16, 09:15 PM
The NASA article also says you can not see colour.
Whereas I could not see colour straight away, and once I could, they were quite faded.
However, the grass IS green, bricks are red. Seems I'm one of those with the "very mild superpowers".. :-)

See if I can remember checking again when there is a half moon. That would be interesting. -I suspect the colours will be gone then..

Peter

CJSF
2011-May-16, 09:19 PM
I think I can, when it's full. I'll have to check and vote when I know for sure. I know that I often make my way though my house with just the scant ambient light coming through window cracks and such at night, and will read a soy milk carton or cereal box while getting a late night/early morning snack... seems dimmer than the full moon those times... will have to revisit this thread when I've done it (assuming I remember).

CJSF

chrlzs
2011-May-16, 09:42 PM
Thanks for all the replies, folks - it looks as if there is a wide range of moonlighting abilities! I particularly appreciate those who have given it a genuine test - don't forget to give your eyes a few minutes to dark adapt (ie if you glance at the moon, you will need to close your eyes or look into complete darkness for a few minutes before trying to read.

BTW, I forgot to mention - I have mild red-green colourblindness (protanopia). I wonder if that may be related to better low-light sensitivity? Fate giveth and taketh away..!

baskerbosse
2011-May-16, 10:51 PM
Well I have rather extreme myopia. Perhaps my glasses mean I collect more light per area retina, giving me the ability to see colour in moonlight.
(I'll try again to see if I can see colours without glasses on tonight)

Peter

astromark
2011-May-16, 11:36 PM
On a full moon night, sure, pretty easily. I try not to make a habit of it, it isn't very good for your eyes.

That is not true...

WayneFrancis
2011-May-16, 11:59 PM
I can read by moon light but I have very good night vision with my glasses on. But then again I have slightly better then 20/15 vision with them on and I'm almost 41.

WayneFrancis
2011-May-17, 12:00 AM
That is not true...
I'm with Mark. That is an old wise tail. Kids read in unlit rooms all the time because their eyesight is, in general, that much better. Low light doesn't actually cause a strain on your eyes.

WayneFrancis
2011-May-17, 12:19 AM
The NASA article also says you can not see colour.
Whereas I could not see colour straight away, and once I could, they were quite faded.
However, the grass IS green, bricks are red. Seems I'm one of those with the "very mild superpowers".. :-)

See if I can remember checking again when there is a half moon. That would be interesting. -I suspect the colours will be gone then..

Peter

The reason most people can't perceive is more due to the low number of incoming photons and how rods are more geared to low light vision. In essence the brain filters a lot of what we see and at night the amount of information coming from the cones is negligible, often not enough photons actually fall on a set of cones to produce a reaction. Thus the lower amount of light the less likely that the cones will fire off while the rods can pick up a single photon. So full moon would provide more photons to trigger off colour vision then others. It is also possible that you are one of the few people that have 4 different sets of cones in their eyes thus able to not only see colours easier but literally to be able to see colours other people can't.

baskerbosse
2011-May-17, 12:32 AM
It is also possible that you are one of the few people that have 4 different sets of cones in their eyes thus able to not only see colours easier but literally to be able to see colours other people can't.

I thought tetrachromatic vision was limited to women for genetic reasons..?

Peter

Solfe
2011-May-17, 01:14 AM
I can read in moonlight but have trouble with small text, but I find it much harder when there is snow on the ground.

Here is an odd thing I noticed about my night vision. Sitting next to a swimming pool at night with a underwater light wrecks my night vision and causes the sky to take on a red tinge. I think that is pretty normal, but I am still surprised at how red the night sky looks every time it happens.

I also stumbled across a funny related effect. Watching TV shows with lots of yellows makes my night vision better for a while. I noticed this when watching a Farscape episode where a "different dimension" is represented with yellow filter. Obviously I have to be watching TV in the dark and then step outside.

Cougar
2011-May-17, 01:16 AM
I'm with Mark. That is an old wise tail. Kids read in unlit rooms all the time because their eyesight is, in general, that much better. Low light doesn't actually cause a strain on your eyes.

You're phonetically very close, and there's no misunderstanding as to what you meant, but actually it's "old wives' tale." I'm glad to hear of your agreement with Mark that low light doesn't strain your eyes. I normally like the lights down low. :)

I think Ivan nailed it with respect to the geo-physical parameters affecting one's ability to "read by moonlight." And in general, humans' "night vision" slowly deteriorates with age, I hear. :whistle: But I distinctly recall when I was living in the Kenyan highlands, on full-moon nights, you could walk around in the bush like it was daylight.

Strange
2011-May-17, 02:02 AM
Can I read by moonlight? No. Well, not during the day anyway. It is washed out by all that sunlight.

baskerbosse
2011-May-17, 04:12 AM
You're phonetically very close, and there's no misunderstanding as to what you meant, but actually it's "old wives' tale."

I think the politically correct term is "information item from a mature female domestic engineer".. ;-)

WayneFrancis
2011-May-17, 04:35 AM
I thought tetrachromatic vision was limited to women for genetic reasons..?

Peter

I'll take it you are male? Not an assumption I make in forums :)

WayneFrancis
2011-May-17, 04:37 AM
You're phonetically very close, and there's no misunderstanding as to what you meant, but actually it's "old wives' tale." I'm glad to hear of your agreement with Mark that low light doesn't strain your eyes. I normally like the lights down low. :)

I think Ivan nailed it with respect to the geo-physical parameters affecting one's ability to "read by moonlight." And in general, humans' "night vision" slowly deteriorates with age, I hear. :whistle: But I distinctly recall when I was living in the Kenyan highlands, on full-moon nights, you could walk around in the bush like it was daylight.

Ah thanks for the correction...hmmm bit sexist term then aye.

Cobra1597
2011-May-17, 04:47 AM
I'm with Mark. That is an old wise tail. Kids read in unlit rooms all the time because their eyesight is, in general, that much better. Low light doesn't actually cause a strain on your eyes.

I fully admit to not being an optometrist :lol:
There are certain things in life where, for lack of any real problem caused by doing so, I've deferred to "what my mom told me growing up." Generally this doesn't extend to sciences, but sometimes to personal health. In this case, I didn't have much reason to look into it since reading in dimly lit rooms isn't something I tend to do a lot anyways. I don't like reading in dim light.

Good to know it is an old wive's tale. I'll make sure my kids (whenever they come along) are told better information.

Tensor
2011-May-17, 05:26 AM
Well, I just went out to check. I had no problems with the large print, but did with the smaller print. Then I realized that I had left my glasses in the house (I don't use them for the computer). After getting the glasses, I had no problem with the smaller print either. And that was just walking out into the moonlight. No adjustment time. I could also make out colors, but it was weird. Light blue, blue and red were no problem. Green, was a problem. I would have thought that the colors on one or the other end of the spectrum would have been the problem. Not the one basically in the middle.

WayneFrancis
2011-May-17, 05:45 AM
Well, I just went out to check. I had no problems with the large print, but did with the smaller print. Then I realized that I had left my glasses in the house (I don't use them for the computer). After getting the glasses, I had no problem with the smaller print either. And that was just walking out into the moonlight. No adjustment time. I could also make out colors, but it was weird. Light blue, blue and red were no problem. Green, was a problem. I would have thought that the colors on one or the other end of the spectrum would have been the problem. Not the one basically in the middle.

I wonder if this is because green normally stimulates all 3 sets of cones but in low light conditions our brain, not receiving as much input from all cones, might muddle the colour green while blue and red are more distinctive since they are primarily received by only 1 set of cones.

baskerbosse
2011-May-17, 06:42 AM
I'll take it you are male? Not an assumption I make in forums :)

Yes,
And I am completely unsympathetic to shades of pink being referred to as "completely different colours". ;-)

Perikles
2011-May-17, 08:16 AM
I tried it last night - an almost full moon, but behind thin cloud. I could read normal print but with difficulty.

CJSF
2011-May-18, 01:23 PM
Unfortunately, there really wasn't anywhere for me to go, conveniently, to get my eyes dark adapted to test this with a full moon last night. I will have to wait for a future attempt. It's possible I might be able to test with a gibbous moon in a few days time, but I am not sure yet.

CJSF

shriram
2011-May-18, 03:05 PM
I have tried it only once or twice, and that to during full moon. I could read properly. We used to go on a night trek sometimes. It is amazing how strong the moonlight is during full moon. We could climb without using any torchlight.

ShinAce
2011-May-18, 03:38 PM
You're phonetically very close, and there's no misunderstanding as to what you meant, but actually it's "old wives' tale." I'm glad to hear of your agreement with Mark that low light doesn't strain your eyes. I normally like the lights down low. :)

I think Ivan nailed it with respect to the geo-physical parameters affecting one's ability to "read by moonlight." And in general, humans' "night vision" slowly deteriorates with age, I hear. :whistle: But I distinctly recall when I was living in the Kenyan highlands, on full-moon nights, you could walk around in the bush like it was daylight.

*Bob Marley singing*
"Turn your lights down low
And pull your window curtains;
Oh, let Jah moon come shining in -
Into our life again, "

I am fortunate enough to be able to read in the dark. I squint to read footnotes on some books, but that's extremely small print. Likewise, on a clear night, we setup camp without fire. A flashlight usually results in choice words being spoken. Why ruin a good thing with a flashlight?

Oh, and old wise tail. That's going to make me smile all day.

blueshift
2011-May-19, 01:36 AM
I can't read with my glasses on in either sunlight, moonlight or sitting next to a 100 watt light bulb. I have to take them off in all cases and even then I have to reread something about 8 to 23 times before anything sinks in.

profloater
2011-May-19, 06:45 PM
On a full moon night, sure, pretty easily. I try not to make a habit of it, it isn't very good for your eyes. Why would it be bad for your eyes just to be dark adapted?

WayneFrancis
2011-May-20, 02:22 AM
I tried last night but it was overcast...but I can tell you I can read by light pollution light.

profloater
2011-May-20, 11:35 AM
I believe full dark adaption takes much longer than a few minutes, maybe even an hour but is cancelled quickly by bright light. A WW2 Fighter pilot I knew said he and others wore a black eye patch for night flying so that if dazzled they could whip off the patch and see again.

chrlzs
2011-May-20, 12:57 PM
Why would it be bad for your eyes just to be dark adapted?

I've never seen any claim that dark adaptation was in any way bad for your eyes. I believe the myth about low-light being bad for your eyes stems from the fact that when you read in low light, your eyes are forced in two opposing directions...

Let me explain! First, your pupils want to dilate as much as possible to let the maximum light in (just like fully opening the aperture on a camera..) But as camera enthusiasts know, when you do that you lose depth of field. Your eye has a similar problem - in order to focus on fine text, it wants to use a *smaller* aperture (that's why people tend to squint when looking at tiny or distant details - you can increase your depth of field and increase the range of distances that are in focus at any given time...

So your eye physiology has muscles competing with each other = eye strain. (I'm no opthalmologist, but that's my understanding..)


As an aside, I'm gettin' a bit older and my eyes do not focus as well as they used to, so I have two sets of glasses - one for daytime use, and one for nighttime. The daytime ones are weaker, because in daytime my pupils are shrunk and my depth of field expands out to just reach infinity. But if I use those at night I can no longer focus on infinity (and that's no good for stargazing!), so I use slightly stronger ones (about ~0.5 diopter) to get me there.

OK, I'm waffling again - i'll shut up now :razz:..

John Xenir
2011-May-23, 01:28 PM
What about the opposite? Could an astronaut read on Moon at full Earth (being night) or blueness of Earth would not provide enough light?

Besides that I would like to know what is the visibility in the shadows on the Moon during daylight.