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Low-Hanging Moon Explained
gollum123 wrote to mention a BBC article which explains the low-hanging moon of the past few nights. From the article:"For the past few nights the moon has appeared larger than many people have seen it for almost 20 years. It is the world's largest optical illusion, and one of its most enduring mysteries. The mystery of the Moon Illusion, witnessed by millions of people this week, has puzzled great thinkers for centuries. There is still no agreed on explaination for why the moon appears bigger when it's on the horizon than when it's high in the night sky."
Good day, gentlemen. As you are no doubt aware, I have perfected a device capable of altering the orbital path of the moon. First of all, I must offer kudos on a most inspired cover story...'illusion' indeed...really, a first rate piece of propagan-da. Of course, you know it cannot last...
You see, gentlemen, things will only get worse...my device, which I've dubbed 'the Lunatrix', will continue destablizing the moon's orbit, drawing it ever closer to our fragile planet. First, abnormally high tidal waves will decimate all costal regions...then, as the tidal influence grows steadily stronger, geological disruptions will occur on a global scale, tearing apart the earth's crust like fresh bread, releasing the liquid-hot mag-ma within. No place on the planet will be safe...civilization as you know it will cease to exist...that is...unless you pay me...
One hundred billion kajillion fafillion dollaaars!!!
<DramaticMusic>
Gentlemen, you have my demands...peace out.
____
~ |rip/\/\aster /\/\onkey
Duh! Because it's closer!
some guy who got gods powers is trying to get laid... apparently its taking longer than the last guy i saw try this one.
There's nothing Intelligent about Intelligent Design.
This is news?
I was thinking the same thing a few nights ago, watching the moon rise
over LA. Then I considered, "Near the ground, I consider it in proportion to the objects around it. In the sky, I have no reference"
Great thinkers? Centuries? Bah.
Now what they need to figure out is how to fix the pollution in LA. The
moon is red until it gets above the smog. Well, that is if you're not
*IN* the smog.
Serious? Seriousness is well above my pay grade.
The logical conclusion obviously is that the moon *is* bigger when it's closer to the horizon. :)
quidquid latine dictum sit altum videtur.
I heard on various shows that it's because it's closer to things that our mind knows are big when it's close to teh horizon, trees buildings towers etc. When it's high in the sky there is nothing around it.
Some one on some show said that if you bend over doubled and look through your legs at the moon, no matter where it is in the sky it will appear large as well for the same reason
500 dollar reward for tip(s) leading to the arrest of the person(s) who stole my sig.
For the past few nights the moon has appeared larger? Could this open some eyes and increase interest in alternative (Linux, Mac) offerings?
Everyone knows the moon does that because it's made of cheese.
You're only as smart as your brain.
Too bad Princess Leia is away on that diplomatic mission and can't be here to see this.
Don't blame me, I voted for Durga.
If you bend over with your head between your legs and look at the moon upside down, the illusion disappears. (I'm being serious too!)
I'd say the reason is because of how the light bends in the atmosphere, or something like that. I thought "experts" would know better than we do. Or at least figure it out faster. =/
For the past few nights the moon has appeared larger than many people have seen it for almost 20 years. It is the world's largest optical illusion, and one of its most enduring mysteries.
It can put a man in space, land a probe on Mars, but Nasa can't explain why the moon appears bigger when it's on the horizon than when it's high in the night sky.
The mystery of the Moon Illusion, witnessed by millions of people this week, has puzzled great thinkers for centuries. There have even been books devoted to the matter.
Not since June 1987 has the moon been this low in the sky, accentuating the illusion even further.
But opinion differs on why there is such an apparent discrepancy in size between a moon on the horizon and one in the distant sky.
Can the Moon Illusion be explained? Here are two theories
In graphics Two main theories dominate. The first, known as the Ponzo Illusion - named after Mario Ponzo who demonstrated it in 1913 - suggests that the mind judges the size of an object based on its background.
Ponzo drew two identical bars across a picture of railway tracks which converge as they recede into the distance (see pop-up, right). The upper bar looks wider because it appears to span the rails, as opposed to the lower bar, which sits between the rails.
In the same way, with a low-lying moon the trees and houses, which are familiar foreground reference points, appear smaller against the moon, which appears bigger than it really is.
Sceptics of this theory point to airline pilots who also see the illusion, although they have no ground reference points.
Alternatively, there's the theory that the brain perceives the sky as a flattened dome rather than the true hemisphere it really is.
Try for yourself
The theory runs that we believe things immediately overhead, flying birds for example, are closer than birds on the horizon. When the moon is on the horizon, the brain therefore miscalculates its true size and distance.
Then there are those who scoff that this is an illusion at all. They, at least, can be proved wrong. Hold a coin up to a low-lying moon to and compare differences in size. Any difference will remain exactly the same, as one traces the trajectory of the moon through the night.
Indeed, it's said that by viewing a low moon though a rolled up piece of paper, to block out the surroundings, the illusion immediately vanishes.
But experts have yet to agree on either or, indeed, any explanation. For the moment at least, the real reason for the Moon Illusion remains up in the air.
It's amazing how much of how our brains and sight work together to recognize object's size and position creates these kinds of illusions. It just shows that even a finely tuned system that works well in everyday use can be caught out, and how because we rely on our vision to give us the absolute truth, its shocking when something manages to fool that sense.
Business Voyeur
That's no moon!
Bush, Cheney, etc... the fix is in!
It's called the Ponzo effect. The surrounding horizon makes the moon seem larger but it really isn't.
if you moon the moon there will be more moon?
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
So the title of the submission is: Low-Hanging Moon Explained... and the text of the submission itself says "There is still no agreed on explaination for why the moon appears bigger".
Who writes these titles? Do they even read the submission, let alone the article... (extra scorn if the submitter wrote the title)
Wacky. And I read the article too (before it got posted here). There's definitely no explanation... a couple theories, sure, but they debunk the theories right in the article.
- StaticLimit
When the moon rains its cheese, then the Windows users will switch.
Side note: nice lift. ;)
You can hold down the "B" button for continuous firing.
The moon, like a testicle, hangs low in the night sky.
There goes the karma.
The logical conclusion obviously is that the moon *is* bigger when it's closer to the horizon. :)
... making it more likely to be right.
No, that's the illogical conclusion
-kgj
"Logic is a bouquet of pretty flowers that smell bad."
- Spock
-kgj
Perhaps when it is closer to the horizon, your line-of-sight to the moon also follows closer to the surface of the Earth. Because the atmosphere is denser at the surface, the denser atmophere has a greater lens effect?
No? Well, it was just a shot-from-the-hip thought.
The way I've heard it, humans subconsciously model the sky as a flattened dome. Thus, when presented with two objects of equal apparent size, one on the horizon and one at the zenith, the one on the horizon looks bigger (i.e. is perceived as having a larger actual size) because it's "farther away" than, yet appears to be just as big as, the object that is directly overhead (and thus "closer").
http://www.archimedes-lab.org/moon_illusion/moon.h tml
Assuming a perfect non-eliptical orbit, the moon on the horizon is farther away than the moon directly overhead by almost half the diameter of the Earth.
Additionally, I wrote a college term paper about this illusion and in my research I found the illusion to be less pronounced in denizens of mountainous areas who have less exposure to things like train tracks that extend straight into the horizon. Without that frame of reference, they are less likely to think of objects near the horizon as necessarily being very away.
-- Boycott Shell
I'd really like to see a bit more attention paid to making Slashdot headlines accurate, both by submitters and editors.
I thought the moon appeared larger while on the horizon because suddenly the moon appears to be right next to objects whose size we can comprehend. In the middle of a night sky, the mooon is just a circle of light in a giant black space, on the horizon the moon is much much larger than buildings we know to be enormous. Even if against nothing more than the horizon, it still seems bigger because at least it's next to SOMETHING.
--
RumorsDaily
Everyone knows that cameras add an extra 200,000 tons.
Just because you can mod me down, doesn't mean you're right. Shoes for industry!
Simple enough, if it appears larger to you at the horizon, take a picture, and then take another one when it's higher. Cameras don't have brains.
Noooooooooooooooooooooooo........ech, ehh, ehhhh.......ooooooooooooooooooo!!!!!!!!!!!!!!!!!!! !
seems to have never have seen bruce Almighty...
The title says "... explained" and the abstract says "there is no agreed-upon explanation". Read the frigging article, it's a fluff piece saying nobody really knows what accounts for the illusion.
Fucking idiot.
Don't try that "protecting the children" shit you people use to keep the tits and bad words off my TV. --Seanbaby
The illusion extends to constellations as well. Take a look at a constellation when it is up high and it seems smaller than when it is near the horizon.
Actually more like brutally retarded "science" in the article:
Not since June 1987 has the moon been this low in the sky, accentuating the illusion even further.
I wasn't aware that the moon hasn't set risen or set since 1987. Apparently the moon has stopped moving relative to the Earth.
More detailed cluestick beating: For most points on the surface of the earth, the moon rose and set again at some point within the last ~24 hours as the Earth rotated. Going below the visible horizon is pretty damn "low in the sky".
And the editors have no dates. So they see the phrase "Low-Hanging Moon" and it sort of eats their brains.
You will not drink with us, but you would taste our steel? - Walter Matthau, The Pirates
{ -There is still no agreed on explaination for why -the moon appears bigger when it's on the horizon -than when it's high in the night sky." }
..is complete crap? wtf?
first, i did not read every post so excuse this if it has been addressed.
is the earth round? is the atmosphere also round? so if a nearly clear object is bent does it not act as a lense? so if the atmosphere is between the viewer and the moon, wouldn't it bend light the same as a lense? so now tilt the top of the lense towards the viewer just like the atmosphere is tilted from the viewers point of view. doesn't it make the image larger? so..
{ -There is still no agreed on explaination for why -the moon appears bigger when it's on the horizon -than when it's high in the night sky." }
I love how many people say that the answer is obvious, but they don't agree with the other obvious answers that are listed.
...it merely looks smaller when it's high in the sky.
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
The more you drink...
...the bigger it will seem
20 % alcohol = 20 Bigger moon 40 & alcohol = thats one BIG moon 90 & alcohol = the size of the moon is no longer a concern of yours. You're somewhere else.
What this world is coming to - is for you and me to decide.
The moon is just blossoming in puberty. When it shrinks in size again, the tabloids will wonder what drugs it's been absorbing.
You can hold down the "B" button for continuous firing.
Although it makes some sense that the moon appears larger when its near the horizon due to having nearby points of reference to compare it with, this still doesn't explain why on some nights it appears larger than on other nights from precisely the same vantage point. Odd indeed.
Insert witty comment *here*. I'm fresh out of wit...
up in the sky long enough for me to enjoy the Festival of Time that'll be happing in 3 short days.
So what object can i place next to my penis to make it look larger than it actually is? Those pills from the interweb just aren't working for me.
A blond newlywed was enjoying her honeymoon by staring at the night sky from a Hawaiian mountaintop with her newly betrothed. At one point he asked her which is closer, Texas or the moon.
She thought about it for a moment and then her eyes glittered with a knowing look.
She glanced around dramatically and replied, "Duuuh! Do you *see* Texas?"
-
This joke is intended as humor, no offense to any blondes out there, real or implied.
No blondes were harmed during the creation of this joke.
The Chronic *WHAT* les of Narnia!
I live in a light polluted town (Aurora, IL) so I barely get to see anything besides an ominous orange glow in the sky at night.
But these past few nights I've just been sitting out watching the moon for a few hours at a time, and it really is something to look at if you haven't done so already. I know late night is prime geek computing time, but go outside for 5 minutes and check it out.
The Moon doesn't change sizes (that the human eye can ascertain at least) and it is not magnified by the atmosphere on the horizon. It is merely an optical illusion.
When the Moon is close to the horizon your brain compares its size with terrestrial objects. When its at its zenith, the brain does not. We only perceive it as being larger on the horizon, when in fact our brains are just misjudging its size.
NASA scientists don't know this? Bullshit alert!
it has also been determined by the NYT that this moon is covered in spam zombies.
when they post news stories about optical illusions instead of the bending of light due to the refractive index of the atmosphere.
Once in a Blue Moon (volcanic eruptions, forest fires, burning crops), they remember there's a Red Moon (ditto, more active, different light levels), and then decide to just post about the difference between a Lunar Eclipse and a Solar Eclipse.
-- Tigger warning: This post may contain tiggers! --
There is still no agreed on explaination
There's apparently still no agreed upon way to spell explanation, either.
Here's a simple test to convince most people that the moon is the same size near the horizon then it is in the middle of the sky.
When the moon rises, extend your arm all the way, hold your thumb next to the moon and take an approximate measurement of the moon against your thumbnail. You just need an approximation.
A few hours later, when the moon is higher in the sky, do the same thing.
This seems to be enough to convince most people that the moon is about the same size.
Of course, then you have to deal with the people who think that their thumb strinks as the night gets later, but I can't help you there.
"Can of worms? The can is open... the worms are everywhere."
The moon size illusion is interesting, but a lesser documented moon phenomena is this:
If you stare at a full moon long enough, you'll develop an irresistable urge to pee.
Not since June 1987 has the moon been this low in the sky
Umm... how about twice a day, when it rises and sets?
Who writes this crap?
the moon is inpired by
Look straight at the moon, and then out of the corner of your eye. It looks smaller when not perceived directly. A similar phenomenon can be observed when you photograph the moon. Seeing as the moon has been around for our entire evolution, it's hardl unreasonable that we would have some strange optical processes when looking at it.
it still looks bigger on photographs?
From the headline: "Low-Hanging Moon Explained"
From the article: "Experts have yet to agree on either or, indeed, any explanation."
So... which is it?
Stupid like a fox!
It was explained that it can not be explained.
time is a perception of a being's consciousness
time is your 6th sense, the wierd ones are 7+
Once in a Blue Moon ... is a common way of saying not very often, but what exactly is a Blue Moon?
According to the popular definition, it is the second Full Moon to occur in a single calendar month.
The average interval between Full Moons is about 29.5 days, whilst the length of an average month is roughly 30.5 days. This makes it very unlikely that any given month will contain two Full Moons, though it does sometimes happen.
On average, there will be 41 months that have two Full Moons in every century, so you could say that once in a Blue Moon actually means once every two-and-a-half years.
Take your hand and put it out arms length and use your thumb ot measure the diameter. Try this with the moon at Zeneth and at the horizen. It is the same size. The only difference is that on the horizen, you have something to compare it against. Hence it is all optical illusion.
So how is this news, much less interesting? (Unless you never go outside....)
This message was brought to you by "Lack of Sleep."
The moon IS falling, I picked up another fragment of it this morning! Damn moon and ozone and smog and air and butterflies and pr0n. Wait, forget that last line!
printf($randomline(sigs.txt) \n "-- "$randomline(authors.txt));
-- myself
In March 1999, Sky and Telescope magazine published an article about Blue Moons by Philip Hiscock, who has studied the folklore and history of the expression. In that article, Hiscock traced the many meanings of the expression over the centuries, but noted that the "two Full moons in a single month" meaning couldn't be explained satisfactorily.
In the May 1999 issue of Sky and Telescope, there appeared a follow-up article which proved that Sky and Telescope had in fact created the current meaning by mistake in an article published in March 1946. The author of the 1946 article had misinterpreted a page of the 1937 Maine Farmers' Almanac.
By studying copies of the Maine Farmers' Almanac dating as far back as 1819, the authors of the May 1999 article showed that the compilers of the Almanac used the term to label the third Full Moon in a season which has four.
We have calculated the dates of this type of Blue Moon for the 20th and 21st centuries and put them in a list for you to browse.
It's a delightful irony that Sky and Telescope, in publishing an article in March 1999 on the history and folklore of Blue Moons, should turn out to be celebrating a "tradition" which it inadvertently created in an article 53 years before!
So which definition is "correct"? The authors of the May 1999 article admit,
With two decades of popular usage behind it, the second-full-Moon-in-a-month (mis)interpretation is like a genie that can't be forced back into its bottle.
And Charles A. Federer, Jr., the founder of Sky and Telescope magazine, adds,
Even if the calendrical meaning is new, I don't see any harm in it. It's something fun to talk about, and it helps attract people to astronomy.
http://www.obliquity.com/astro/seasonal.html
The moon illusion can't be caused by an atmospheric effect, because that would affect cameras as well. Since the illusion is sometimes experienced without reference points the Ponzo affect probably isn't the cause. NASA has links to several papers on the subject.
Who writes these titles? Do they even read the submission, let alone the article... (extra scorn if the submitter wrote the title)
Idiots do. See also today's "SPF (anti-spam system) is approved by IETF". It is neither aniti-spam, nor approved.
You're not new here - you should know that!
While it should be common knowledge (as it makes sense) I see many people staring at the moon here, closer to the equator.
....
:)
... it is pouring now too and i'm on my bike ... wish i had a batman suit, or at least my surfing wetsuit :( friday night kinda stuck in the office fixing some sql queries ...
.. there will be chaos and death, pain ans suffering ...
.. rain stopped ... it is just an illusion :) gotta run to start my engine
When it is round it's OK, but as soonas it is a C or a D it really faces in a different direction
creeped me a little the first time I saq it
bigger moon ?
sorry it is DAMN rainy season here, I haven't seen the moon for days
life sux and the moon is probably about to crash into that mudball we call earth
whoops
Late Islamic masculinization of the Arabian Goddess, Al-Lat or Al-Ilat - the Allatu of the Babylonians - formerly worshipped at the Kaaba in Mecca. It has been shown that 'the Allah of Islam' was a male transformation of 'the primitive lunar deity of Arabia.' Her ancient symbol the crescent moon still appears on Islamic flags, even though modern Moslems no longer admit any feminine symbolism whatever connected with the wholly patriarchal Allah.
All Semites had once a cult of the moon as supreme power. When Mohammed overthrew the old religion of Arabia, he did not dare get rid of the moon cult in a radical manner. Only much later was he powerful enough to forbid prostration before the moon (Koran Sure 4:37). Before Islamic times the moon deity was the most prominent object of cults in ancient Arabia. Arab women still insist that the moon is the parent of mankind.
The answer is that it is an optical illusion of your brain, the moon doesn't change.
To test this, go outside at noon (when the sun is highest and 'smallest'), take a penny, close one eye, and hold the penny out towards the sun so that it perfectly blocks the sun. Note how far away the penny is from your eye.
Now go out at sunset when the sun is low on the horizon and seems huge. Again take the penny and hold it out to where it perfectly blocks the sun. You will notice that you are holding the penny at the exact same distance from your eye, meaning the size of the sun is exactly the same, you just perceive it to be huge.
This is a natural adaptation of our brain, allowing us to deal with distance. For example, if you see a huge tower far away in the distance, you know that it is huge, even though in actuality it is very small from being so far away, much smaller than something close to you (like a tree or a house).
What happens with a sun/moon that is low on the horizon is this unintended side effect of our brains dealing with distance. Because it is low on the horizon and is so far away, you perceive it as being huge, when in fact it is the exact same size as when it is overhead.
ever heard of Occam' Razor?
Yes. It says the exact opposite of my assertion -- and it's usually right.
But it's not always right. And where it's not right, that's where the interesting stuff happens.
In any case, the intent of my original post was irony, not epistemology.
-kgj
-kgj
Given that there is a limit to how many characters that the poster can usse for a title, sometimes, loosey descriptive phrases are the only types that fit.
I remember learning about this in Perceptual Psychology a few years ago. The evidence for the mental sky-dome model, in my view, abundant and undeniable.
Studies of children from age 4 to adult suggest that the moon illusion is present in children, and is stronger than it is in adults. It decreases in strength with age. [Liebowitz, H. and Hartman, T. "Magnitude of the Moon illusion as a Function of the Age of the Observer." Science, 130, 569-570.] This study was done indoors in a large darkened room (no other visual cues) with artificial moons at distances of 85 feet.
Now ANOTHER moon illusion the article doesn't mention, is why it appears to be FLAT and not a sphere.
Right. So they explain the phenomenon, the fact that it exists and two of the major theories on why it works. The article then goes on to say that we don't have a bullet-proof model for why it exists. So, Low-Hanging Moon Explained and then There is still no agreed on explanation pretty much sounds right to me.
I thought it was my botany prof who first said it one night while were were staggering home after a hops lab.
"Win treats sysadmins better than users. Mac treats users better than sysadmins. Linux treats everyone like sysadmins."
it's bug in Matrix. A 2D transform/rendering artefact. Ever noticed a simple static texture for moon, with a black circle occlusion blended, no animation at all?
There you are, staring at me again.
welcome to the world of visual perception http://en.wikipedia.org/wiki/Visual_perception what you think you see is only related to what is actually out there... _k
/obscure?
Yes, very obscure. But I got the reference.
Just a guy with an opinion
The bigger it gets, the lower it hangs.
When it's that low use a low powered telescope and find a place you can identify easily.
Then wait a few hours until it's small again and if it's smaller you have your answer.
Course the naked eye also tells you the same thing. There are visible features of the moon that are identifiable and they're huge when it's low. When it's higher up in the sky they are smaller.
The answer is clear there is no mystery.
I doubt very much that it is purely a mental illusion, and I favor the atmosperic lens distortion explanation.
If someone has the right tool (still thinking about what that is) we can measure it tonight and prove the hypothesis....
Err, except that I see clouds out my window....
http://antwrp.gsfc.nasa.gov/apod/ap050623.html
"...Pure GONZO Journalism!"
Seriously...Who are these "great scientists" and thinkers?
On second thought, maybe they're the same that did research on job selection, concluding that "a well chosen career leads to better job satisfaction".
These journalists might know about creating hype out of nothing, but don't know shit about journalism.
Oh, and by the way, the moon doesn't look bigger. It's US that shrink! Quick, give me that tinfoil hat!
There is also still no explaination as to why Slashdot editors don't run their posts through a seplling checkr.
I climbed a 3,000 ft mountain just south of St Helens a few years ago and looking across the valley at the volcano was extremely impressive. It made me think of an enormous cannon. Really puts human activity in perspective...
"Lack of technical competence coupled with the arrogance of power, as usual, leads to no good end."
when the celestial object is more near to the horizon, the light from it is traveling through more atmosphere. this leads to both a broadening of the object(yet, a blurrier object) as well as a red shift in the light.
easy peasy, martin scorsese
and now back to the fallout shelter...
I thought you were going to say: ;) At least, we would always know the truth :P
... see Nine-Foot-Long Outhouse Ladle.)
"But it's not always right. And where it's not right, my assertion is."
Now THAT would be great
Alas, we don't get to always know the truth.
Alternately, it's one of those "beware what you ask for" deals
-kgj
-kgj
I was told, I believe by an aviation instructor, that the reason the moon appears lower is because the light bends around the atmosphere when the moon is positioned low on the horizon.
The bending is caused by the difference in viscosity of the medium that the light is travelling through.
As the line of sight moves closer to the horizon, the amount of fluid (air) that it travels through increases. As such, differences in the atmospheric conditions also modify the effect.
Perception might be a factor, but there is physics at work as well.
.... the moon comes out of the ocean all swollen and waterlogged and as it rises it drys out and shrinks.
And that is a better explaination than any so called reason that has been given to null and void, little by little, the constitution of the United States.
For what is worse than believing the earth is flat and the center of the universe is that some man is the center of the universe.
May the moon fall on them.
The curvature of the earths atmosphere along with the force of gravity beyond this to cause an ever so slight deflection of passing light, results in the magnifying of light effect.
from a pov seeing the moon or sun on the horizon the angle of the atmosphere.... And big objects like dinosuars got burnt up from it when teh atmosphere cleared enough...
M O O N that spells butt..
Well, if you're patient you can prove to yourself it isn't any bigger without standing on your head.
The moon subtends about 2 solid degrees. By fortunate coincidence, this is more or less the same angle subtended by by most adult's fingers when their hand is held at arms length -- very rought it's true, but close enough.
So, just hold your index finger at arms length. It will be wide enough, approximately, to just cover the moon. Remember how it looked. Then look for the moon later when it's higher in the sky and try again. The moon looks much smaller in all that empty sky, but it will be about the same size compared to your finger.
The finger trick is useful for rough angle estimations. A hand width with closed fingers is about ten degrees, and a spread fingered hand (unless you have Marfan's syndrome) is about twenty. If you are really concerned about accuracy, you could calibrate it I suppose and multiply by some factor other than 2 degrees per finger width. I wouldn't use it for civil engineering purposes, but it will do for navigation and star hopping.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
The same effect applies to the constellations, too. I noticed this one night when I got curious about the "moon illusion" effect and looked at Orion low on the horizon, then several hours later when it was high overhead. Orion also appears much larger near the horizon than it does higher in the sky, just as the moon does.
Beyond throwing that out there for anyone to mull over, I'm not going to get into this article anymore... we studied this one to death in my college class on perceptual psychology, and even as much of a science geek as I am, I'm completely sick of, and bored with, the "moon illusion".
So last night driving I saw probably the coolest looking moon in my life.
Low, big, orange-yellow, and a thin cloud covering the mid section like in some horror film.
Now I know why. The big low part, not the color.
Or the cloud, i understand how clouds work.
M-O-O-N That spells moon.
"The price good men pay for indifference to public affairs is to be ruled by evil men." ~Plato (427-347 BC)
Perhaps the fact that when the moon is on the horizon you are viewing it through more atmosphere than when it is directly above.
Because of this, the atmosphere acts as a lens for whatever reason (perhaps because of the spherical shape of the atmosphere itself?) thus making the view of the moon and/or sun larger.
Proceed to tear apart my humble theory.
My high-school science teacher Dad explained this to me when I was about 6 years old.. How is it that these 'great minds' of the world have been grappling with this for so many centuries?
It's refraction... The same reason it's very difficult to catch fish with a spear or bare-handed..
When you look at the water in a stream at an angle, you're not seeing 'in a straight line', the refraction due to the surface of the water causes you to perceive the fish in a different spot than it really is.
This can also be observed in a fish tank (get real, this is Slashdot, do any of us EVER find ourselves wading in fish-bearing streams?) If you look at the tank from the outside, straight-on, you see the fish where it really is. If you look from an angle, however, your perceprion of where the fish is will be distorted in proportion to the angle at which you deviate from the perpendicular (with respect to the side of the tank)
If the surface of the tank were curved (like the atmosphere) you'd perceive the fish to be larger than it is as well.
In the moon's case, if you are looking straight up at the moon when it is directly overhead, you're experiencing as little atmospheric/curvature distortion as possible. As the moon gets lower in the sky, the refraction becomes more pronounced resulting in the perception of a larger moon...
I dub this the Archibald Castell Jr. (Dad) theory of moon illusion.
I assume I'll be contacted by the Nobel people soon...
There is still no agreed on explaination for why the moon appears bigger when it's on the horizon than when it's high in the night sky."
m o/astro/demo/8c2040.htm
No one agrees? What? It's a natural lense effect created by the gravitational field produced by the earth. It's called the "Gravitational Lens Effect"
http://www.physics.brown.edu/physics/demopages/De
View diagram. I did this in 30 seconds. It's not to scale by any means and not even the correct angles, but it's enough to get the point across.
Notice the amount of atmosphere that is in the path between the PAW and the moon in the two different positions. I imagine this additional atmosphere at the horizon angle distorts the image of the moon like a magnifying glass compared to when it's right above.
I don't know why people can't seem to understand this. Its all about atmosphere. When the moon is high in the sky, the light being reflected from it only passes through a certain amount of atmosphere. When the moon is close to the horizon, its light passes through much more of the atmosphere than normal. As the light passes through the atmosphere of the horizon, the atmosphere acts like a telescope and magnifies what you see, making the moon appear much larger. The same effect can be seen every sunrise and sunset with the sun. Ever notice how the sun appears so much larger in when it rises and sets? I don't believe the originator of the BBC article was dumb enough not to ask a meteorologist(sp?) before writing that article.
That's a Space Station!
However, it IS worth noting that you mentioned mountainous regions, whereas ancient Egypt was relatively flat, and most Western societies have moved into plains and low-lying regions. I could very easily see a mountain-based society developing much better ability to perceive distance and size, as that would make a big difference when it came to survival.
On the other hand, plains-dwellers don't need to care so much, as climate would be a far bigger factor than the exact line you took. It may well be that accurate perception has simply not been necessary enough for most societies to retain.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
The Straight Dope answered this one 10 years ago: Why does the moon appear bigger near the horizon?
It doesn't show on photos.
Theory torn apart.
There's surely some distortion caused by the atmosphere, but what we got here is mainly an optical illusion of some sort. I didn't read the linked article, but eyeballed through a feature NASA had on it a few days ago. They had a photo of the moon moving (multiple exposures). There was no change in size.
I'm not sure how much of the size change (if there were one) would show on a regular photo though. Cameras doesn't zoom in like the eye does, which you soon notice if you try to take a photo of a bird or stars with a regular camera. Birds just become a little black mark. I've heard the focus area of the eye is like a cookie held an arms length away. The rest is fuzzy. At the extreme edges and even outside the field of vision the brain/imagination fills in the details.
I would guess that stereovision of importance in the case of the moon illusion.
1: Anyone tried to see what happens if you close one eye?
2: Anyone tried to make a virtual (3D goggles) replication of the setup?
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reason the sun does. The brain id fooled by perspective which is not there when the moon is far from the horizon. They also look larger when there is more red because the eye is more sensitive to red. This is why you don't want a red car if you like to exceed the speed limit. Sometimes, when the local temp gradient is just right, they will appear larger because the cooler air near the ground is more dense and bends the light that is nearer the ground bfurther. It's generally a small effect.
Have any of you guys noticed that some tall buildings look wider at the bottom than the top,
even though they have straight sides?
Fat sun, fat moon crooked building all same same...
If it's just a illusion caused by the brain, then howcome the moon is different sizes in photos too?
how come it looks it looks big when it comes out and then diminishes in size.
Is due to articles like this one.
"Well, good luck finding a judge that doesn't run a bestiality site."
Slow news day, eh?
I remember seeing a picture that says a thousand words about this a few years ago.
Mmmm.. Donuts
...it's a bug in the software.
For the past few nights the moon has appeared larger than many people have seen it for almost 20 years. It is the world's largest optical illusion, and one of its most enduring mysteries.
What is this optical illusion everyone's talking about? The moon always look 3476 km wide to me.
I would honestly like to know how the hell this made it on Slashdot. Moreover how anyone could be so daft as to call this optical illusion inexplicable. It's quite simple, in fact its retardedly elementry. Its called comparative persepective. Simply put, when the moon is close to terrestrial objects (the ground) it looks larger because you are comparing its size to things on the ground (hills, buildings, etc.). Simple huh? Don't believe me? Do this, go outside, if the moon looks large... put your hand up and block out everything bellow the moon with it. TADA! Like magic the moon appears normal. Now, everyone go kick yourself in the ass for thinking this should have been on slashdot, and if you already knew what I have stated here, then give yourself a pat on the back for not being a brain dead simp and join me in sighing at the poster of this obsurd peice of news. And to anyone I offended, TOO BAD! ^_^
_______
Death wish, n.:
The only wish that always comes true, whether or not one wishes it t
The real travesty is that, after inventing the technology to go to the moon and return safely, no human has been there in nearly 33 years. They gave up on the last 3 Apollo missions and no one has been since Apollo 17. It's disgusting. I want my moon base and I want it now!
Far too far long ago
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Take a glass ball, cut the top 20% or so of the ball off and in half. Look from the flat side through to the other side. Stick a pea on a toothpick and freaking look at it. WTF?
There is still no agreed on explaination for why the moon appears bigger when it's on the horizon than when it's high in the night sky. Umm.... Yes there is. Hell, I learned this when I was in about third grade, in fact. It's because when the moon is lower (on the horizon), it's eaiser to compare it's size to things you can see, like buildings or a field or something. When you look straight up into the sky when the moon's high, there's nothing to compare it to, other than stars who's size you can't exactly determine by your eye, either. The fact that I knew this since third grade, and NASA can't think of anything better is really sad. I mean, when you're shown the Ponzo Illusion theory, it's kinda hard to say "Well, there's really no explanation for this phenomenon." It's explained to you right there. I sometimes wonder who's in charge around here.
My theory is that the reason for the moon to look bigger in the horizon is due to water molecules in the air. As the moon gets closer to the horizon the amount of water molecultes between the observer and the moon is higher hence the "magnified" size moon.
Step 1: look at the moon near the horizon
Step 2: now, block out the horizon and all other objects with your hands, and look at the moon
Step 3: ???
Step 4: Profit!
Also works with the sun!
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I was discussing this recently with a friend, and she suggested that the atmosphere was acting like a magnifying lens. This kind of makes sense (curved body of a different density), though I am unsure its effects would be sufficient to make the moon seem _that_ big.
"I think it would be a good idea" Gandhi, on Western Civilisation
ohh it isn't closer to earth when it is on horizon? :( and I thought... sniff...
you insensitive clod!
all I can say is "GOD DAMN IT".
I live in a light polluted city, and wish I had known about this earlier. The moon, along with most other astronomical(sp?) observations enthrall me.
well shucks.
this thread is worthless with out pix.
I've always assumed it had something to do with the angle the light is entering the atmosphere and the angle at which we're perceiving it. That is, maybe like shining light through glass it bends and twists... But then again, light always comes out the same size when passed through glass. But maybe its something similar? The particals in the air, somehow pick up the light and illuminate it at different angles?
I've always felt it would be something to do with the atmosphere, rather then an illusian as described.
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witnessed by millions of people this week, has puzzled great thinkers for centuries
Ok, I can understand that people who know, have read, have studied, etc. color/color appearance/vision/etc. theory and applications must be few in number [relatively speaking], still, writing about this as being some long time unsolved mistery, is just crap. Descriptions of such and similar vision-related pecularities have a really wide literature, some of which I also have read and studied, the most recent being a book of Arne Valberg, which also has a chapter about such topics, and the moon-size subject is also mentioned.
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Nah, Lunatrix is a derivative (read anagram) of "an Ultrix", which is (was?) a proprietary (DEC) Unix, so there is no GNU.
I have discovered a truly marvelous proof of killer sig, which this margin is too narrow to contain.
The reddening thing does do sunsets, but the "broadening" effect isn't what you are looking for.
It's not easy, it's one of the things that bugs me every single night that the moon is out. I've stood on my head, blinked rapidly, looked through a cardboard tube, to figure out what it is.
What it isn't is any actual effect. Easy way to disprove that is with a digital camera. Take a picture at moonrise, then one with it high in the sky. Then load them both on your machine, and check the widths.
Of course, the older "light etching" cameras work the same.
Now try to simulate the effect by holding a quarter out, and then holding it above your head. Doesn't work for me.
It is infuriating to me, honestly. It seriously feels like science has failed, even though I know there are good possible explanations. It just seems like, we can SEND A MAN THERE, we should know why we're all on the perceptual equivalent of an acid trip when we look at the damn thing.
Drives me nuts! Why don't street lights seem bigger? Why do mountains? How are we telling "background" from "foreground"?
The big question: how many *OTHER* more subtle things do we percieve as being the "wrong size"? Do we inflate faces like that? I've been getting into photography, and what was majestic in person (and through the viewfinder, many a time) is a tiny speed bump in the photo.
Is the world AT ALL like we percieve it?
At least it's on slashdot. I'm expecting good comments here!
You're plain wrong, and sadly, You're Dad too :)
;)
it can't be refraction, because experiment with coin (or rolled paper or your thumb) wouldnt (if it was refraction) revert the effect. but this expermients instantly revert the big size.
You dont believe that refraction can be disabled by your thumb or coin, do You?
It's been known in plain science for centuries that if you measure the angle of the moon's diameter with some uh, apparatus (a theodolyte does the job, but i'd save my money and use a camera) , this angle doesn't grow when the moon is just above the horizon. So the conclusion, that the effect is an illusion, is well established since long.
The reason a final statement on the effect is hard to reach is because they're trying to explain the mechanics of the illusion.
Of course we all know, as most of those who've taken the time to stick a thumb at arms length into high moon and a horizon moon, that the big low hanging moon is mostly an optical illusion.
Yet it isn't a pure one, since the focal length of our eyes change when we raise our head. This effect most certainly varies from person to person, but can be observed if you concentrate on the focal behaviour of your eyes and it's abilty to change it's focal length.
Which, by the way, can be trained. There are older reports of north american natives you could see better with the naked eye than a pioneer with binoculars.
We suffer more in our imagination than in reality. - Seneca
Basically, what this means is that the moon is the correct size on the horizon, and this "bug" causes it to look too small when it is high in the sky.
I would like to propose a hypothesis why this is actually not a "bug" but has a purpose: gravity and hand-to-eye-coordination.
Most of us may have noticed that when you throw things, the things won't keep going straight to that direction, but fall to ground. We are pretty good at throwing at things far away rather accurately. You don't need to calculate the "launch parameters" mathematically, but you just look at the target and your brain "just does it".
Now, if something is 20 meters up above, you need to throw a lot harder than when it's 20 meters away horizontally. Therefore, your brain makes it look like it's farther away to compensate. This may be a bit indirect way of compensating, but that's often how the nature works.
Just a 2.4132 cents worth from your AI guy.
As soon as you tilt your head up or down the inner ear gets stimulated and sends an interrupt to the brain.
So when you look up to the moon your frontal lobe may think about space, but your subconscious brain thinks about not falling and reduces the priority of visual stimuli.
I thought this was common knowledge. It has to do with the optical properties of the atmosphere. Objects viewed through a thicker atmosphere (or at more of an angle, so that the light passes through an effectively thicker slice of the atmosphere) look larger because the light is diffracted more -- like when you look through a convex lens. It's related to the reason why sunsets are red, the noonday sun yellow, and the rest of the sky blue (because blue light diffracts more readily than red), which is why when the moon (or sun, for that matter) appears larger, it also appears redder.
More stuff (clouds, dust, whatever) in the atmosphere means a larger, redder moon and prettier, more elaborate sunsets.
C'mon, this isn't exactly quantum mechanics. More like high-school physics.
Cut that out, or I will ship you to Norilsk in a box.
Neat, but the moon doesn't subtend 2 degrees - it's actually about half a degree in diameter.
The human brain distorts inclines, especially when faced with the prospect of humping upward. Hills near me rated as a ten percent grade appear to my eye as a 30 percent grade. My opinion is that this is the brain's attempt to project visual 3-space onto a manifold of equal effort. It's a huge energy mistake to take the direct route to a food source over a rise in the terrain rather than taking a longer path that partially skirts around the rise. Not only does it cost energy, it can leave you feeling sweaty and cold on the downslope.
I think when the moon drops close to the horizon it triggers the "how hard would I have to hump to get there" reflex. The side effect of the moon's engorgement is that the apparent difference in grade from the bottom rim to the top rim is perceptually magnified, which is exactly what you'd need to take into minute account if you setting out on happy trails.
How much brain glucose did you expend while reading this trying to figure out if I was talking about something else? On the basis of six words.
It has been proven that 2 grams of Psilocybin mushrooms will correct for the perceived size change, however you will feel as though you are standing upside down.
Fool! don't you know your plan will fail! and you will be stopped by Her Majesty's Secret Service... Put the moon back where it belongs and don't let me catch you trying anything like that again. When will you people learn, move along now folk's there is nothing to see here, let HMSS deal with this, 'now where did I put my Evil Genuis zapper!
My physics teacher once explained the following, which is in line with the 2nd theory in the article: when you look down from the top of a large building, anything you see below, like cars and people, looks very small. When you see equally large objects from te same distance, but horizontally, they appear much bigger. He mentioned that this could be due to evolutionary changes in the brain, to have approaching predators like lions and tigers stick out larger and have a more alarming effect.
The number of people who don't just start out not believing it, but wondering "how come no one compares it to a penny or takes a pictue?"
What I think is most interesting is that the moon is the same size, but don't you normally feel like you have to "squint", or try hard, to see the details of it when it is directly overhead? And don't they just seem to be ALL UP IN YOUR FACE when it's near the horizon?
This is the detail that bugs me the most, actually, because it implies that the illusion is at least in some degree "objects in center of sky appear smaller" than just the more straightforward "objects at horizon appear bigger".
I would agree with you. I always thought that it was refraction because the angle at which the light hits the atmosphere. Same thing happens to the Sun is going down at the end of the day.
>> the illusion disappears. ...because all you can see is ass and balls.
The government which is strong enough to protect you from everything is strong enough to take everything from you.
Is this some Northen hemasphear thing im not aware of, I watch the moon rise and set quite a lot, so how is this the first time americans are seeing the moon so low in 20 odd years??
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In USA the size of the moon is determined by the need that the text Cocal-Cola written across it remians clearly visible to the naked eye. See:3 &cid=12595675
r moon%20(shadow).jpg
http://science.slashdot.org/comments.pl?sid=15020
In Japan, the minimum visible diameter of the moon is determined by the height of a klutzy schoolgirl named Usagi Tsukino. See:
http://butterflydeath.blogs.sapo.pt/arquivo/Sailo
On a related note, check out this
As the light enters our eyes and into our brain, our brain automatically processes the information (in this example, if we see an object in a shadow we automatically assume that it must be lighter than it appears). What's happening in this example is probably similar to the low-hanging moon illusion.
http://facstaff.uww.edu/mccreadd/