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Topic: Moon illusion

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	The Moon Illusion
		Some studies have asked subjects "which moon seems nearer", which seems an unfair question, but still one cannot deny that we have mental processes that produce at least an approximate subconscious judgment of "near and far" for things in the sky, and this is certainly relevant to the sky illusions.
		Proponents of this hypothesis as explanation of the moon illusion argue that if there are a number of distant objects in the field of view, as there would be when observing the rising or setting full moon, the brain adjusts accommodation and convergence to them.
		Understanding the sky illusion may be the key to understanding the moon illusion, but to merely invoke the sky illusion as the cause of the moon illusion evades the fundamental issues, and is empty of content.
	www.lhup.edu /~dsimanek/3d/moonillu.htm (8836 words)

	Moon illusion - Wikipedia, the free encyclopedia
		It is common belief that the moon appears larger near the horizon due to a magnification effect caused by the Earth's atmosphere.
		When the moon is near the horizon, holding a small coin at arm's length with one eye closed, positioning it next to the moon and comparing the size of the coin relative to the size of the moon reveals its relative size for that given situation.
		According to the angle of regard hypothesis, the moon illusion is produced by changes in the position of the eyes in the head accompanying changes in the angle of elevation of the moon.
	en.wikipedia.org /wiki/Moon_illusion (1086 words)

	Moon - Wikipedia, the free encyclopedia
		The gravitational attraction that the Moon exerts on Earth is the cause of tides in the sea.
		The tidal bulges on Earth, caused by the Moon's gravity, are carried ahead of the apparent position of the Moon by the Earth's rotation, in part because of the friction of the water as it slides over the ocean bottom and into or out of bays and estuaries.
		The points where the Moon's orbit crosses the ecliptic are called the lunar nodes: the ascending node is where the Moon crosses to the north of the ecliptic; the descending node where it crosses to the south.
	en.wikipedia.org /wiki/Moon (6209 words)

	The Moon Illusion
		Alma College, Alma, MI The overestimation of the size of the moon on the horizon compared with the estimated size of the moon positioned higher in the sky, is known as the moon illusion.
		In 1962, Kaufman and Rock concluded that the moon illusion was in fact dependent on the presence or absence of terrain.
		As Figure 1 shows, the magnitude of the moon illusion was greatest in the pictures with a normal orientation with a difference of.156mm between low and high moon.
	www.alma.edu /departments/psychology/SP99/LK/LK.html (938 words)

	The Moon Illusion (Site not responding. Last check: 2007-10-11)
		Incidentally, the reason the moon looks kind of orange when low in the sky is because the light is passing through the thicker atmosphere along the horizon so we are seeing the longer wavelengths of light, toward the red end of the spectrum.
		And the image is rotated just a bit because when the moon was on the horizon, I was facing east to take the image and when the moon was overhead (on the meridian), I was facing south to take the image.
		As I have shown, the actual image of the moon on the horizon is the same size as the image of the moon when it's overheard.
	www.mindspring.com /~jeffpo/moonillu.htm (1459 words)

	From the Cover: Explaining the moon illusion -- Kaufman and Kaufman 97 (1): 500 Data Supplement - Supplemental Data -- ...
		In the elevated moon example the same moons are presented with the landscape is absent.
		In the case of the natural moon illusion one sees the apparently smaller elevated moon in isolation and, because of its smaller apparent size, observers often make the logical inference that it is farther away.
		The demonstrations are not identical to the experimental situation because the depth between the left-hand and right-hand moon is scaled by the distance between the viewer and the computer screen.
	www.pnas.org /cgi/content/full/97/1/500/DC1 (481 words)

	Moon Illusion - Picture - MSN Encarta
		When the moon is close to the horizon, it seems larger than when it is in the sky overhead.
		Psychologists today still debate the cause of this illusion, which has fascinated scientists and philosophers for centuries.
		Here the moon looms large over the San Francisco skyline.
	encarta.msn.com /media_461547593_761573665_-1_1/Moon_Illusion.html (46 words)

	Grand Illusions - Optical Illusions - The Moon Illusion
		The moon illusion is one of the most famous of all illusions.
		Yet the moon, a quarter of a million miles away from the earth, always subtends the same angle wherever it is in the sky, roughly 0.5 degrees.
		One extension to the moon illusion that I learned about in a psychology class in college, is to use after images to demonstrate this effect.
	www.grand-illusions.com /opticalillusions/moon (623 words)

	From the Cover: Explaining the moon illusion -- Kaufman and Kaufman 97 (1): 500 -- Proceedings of the National Academy ...
		to be nearly twice the diameter of the elevated moon (1, 2).
		moon is determined by the ratio of its angular extent to that
		The cues most relevant to the moon illusion are those related to the distance between the observer and other external objects.
	www.pnas.org /cgi/content/full/97/1/500 (4879 words)

	Moon Illusion
		Others have proposed that the Moon Illusion had to do with the fact that the eye-brain system is designed to work on the horizontal plane, not the vertical plane.
		The illusion is not that the horizon Moon is larger, but that the overhead Moon is smaller in size than it "ought" to be.
		The effect of this illusion is due mainly to the fact that our brain interprets the sky as being farther away near the horizon, and closer near the zenith (directly overhead, see fig.
	www.archimedes-lab.org /moon_illusion/moon.html (748 words)

	Optical Illusions Etc: free, scary, word & picture optical illusions
		This is known as "The Moon Illusion", I have heard of this illusion before but I hadn't thought about it in a while, that is until the last full moon.
		The Moon Illusion Explained -- According to Don McCready, a Professor Emeritus of Psychology at the University of Wisconsin, the Moon Illusion is caused by oculomotor micropsia/macropsia.
		Summer Moon Illusion -- The lowest-hanging full moon in 18 years is going to play tricks on you this week.
	illusionsetc.blogspot.com /2005/11/moon-optical-illusion.html (619 words)

	The Moon Illusion Explained
		If you wonder why this famous moon illusion occurs, you should read the following article, for, as illusion researchers know, a new explanation is needed: The explanations currently offered by textbooks and the popular media (including virtually all the 'moon illusion' sites on the internet) simply do not explain the moon illusion.
		Thirdly, this article reviews the new theory that the moon illusion is an example of the less familiar, but ubiquitous, "size" illusion known as oculomotor micropsia/macropsia.
		In other words, the new theory for the moon illusion is not simple: But it currently is the most satisfactory explanation.
	facstaff.uww.edu /mccreadd (409 words)

	Moon Illusion
		The “moon illusion” lets objects near the horizon look larger than when the same object is high on the sky.
		The moon in the neighbouring picture is of “aesthetically correct” size.
		The moon illusion is usually explained through size constancy, with the additional –and necessary– assumption that the ‘default’ distance for any object is less than the horizon/skyline distance.
	www.michaelbach.de /ot/sze_moon/index.html (112 words)

	[No title] (Site not responding. Last check: 2007-10-11)
		This is the famous "Moon Illusion" and, despite your protestations to the contrary, the Moon is not larger on the horizon than it is in the zenith.
		In fact, since you are observing the Moon from a round Earth, the Moon is closer to you (by about the radius of the Earth) at the zenith than at the horizon and thus appears slightly larger when it is overhead, just the opposite of the Moon Illusion.
		Despite attempts at a physical explanation, the Moon Illusion is not a physical phenomenon.
	www.eiu.edu /~scienced/3290/science/moon/bigmoon.html (405 words)

	The UnMuseum - Experiment: Ponzo and the Moon
		When the moon is at the horizon, objects on the horizon such as buildings and trees give us distance clues that the moon is very far away.
		The moon, of course, is beyond the sky and so far away that, unlike clouds, planes and birds, it does not really change size based on being overhead or near the horizon.
		Our mind will reach the conclusion that because the moon is near the horizon it must be far away, but since its size doesn't seem to decrease, it must be much larger than it is when it is overhead (when we think of it as being closer), and we see it that way.
	unmuseum.mus.pa.us /exmoon.htm (900 words)

	Moon Illusion Solution
		Space-age measurements, in fact, have confirmed that the moon is actually 2,162 miles in diameter and it is indeed 238,900 miles "farther away."
		The diameter of the moon itself, therefore, corresponds to 360/694 degrees.
		hroughout history, people have judged the moon to be much larger when it is rising or setting than when it is seen at high elevations.
	www.niquette.com /puzzles/moonills.htm (350 words)

	Moon Illusion (Site not responding. Last check: 2007-10-11)
		The image the full moon casts on the retina is always the same size regardless of the moon's location in the sky, so that can't be it.
		When the full moon is near the horizon, therefore, we tend to see it as being further away than when it is overhead because it looks like it is on the inside surface of the big bowl.
		Since the moon casts exactly the same size image on our retinas no matter where it is located, we have an inconsistency to resolve.
	home.alltel.net /billpen/Moon.htm (683 words)

	Guardian Unlimited \| Special reports \| Patrick Moore explains the phenomenon of the moon illusion
		When the moon is high there is nothing with which to compare it; and this is why, according to Ptolemy, it looks smaller.
		You can see the effect at any full moon, but this week it has been particularly well seen, because this full moon has coincided with the time of the summer solstice, when the midday sun is as high as it can ever be.
		Obviously, the sun and full moon must be exactly opposite in the sky, so since the sun is at its highest the full moon must be at its lowest.
	www.guardian.co.uk /space/article/0,14493,1513506,00.html (483 words)

	BBC NEWS \| UK \| Magazine \| Why does the moon look so big now?
		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.
		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.
		When the moon is on the horizon, the brain therefore miscalculates its true size and distance.
	news.bbc.co.uk /2/hi/uk_news/magazine/4619063.stm (481 words)

	Summer Moon Illusion
		This week's full moon hangs lower in the sky than any full moon since June 1987, so the Moon Illusion is going to be extra strong.
		When the moon is near the horizon, your brain, trained by watching birds, miscalculates the moon's true distance and size.
		Psychology at the University of Wisconsin, the Moon Illusion is caused by oculomotor micropsia/macropsia.
	science.nasa.gov /headlines/y2005/20jun_moonillusion.htm (719 words)

	Moon Illusion (Site not responding. Last check: 2007-10-11)
		However, to the astronomical novice, the Moon as viewed on the horizon is considerably larger yet when photographed we are very much disappointed.
		If you were to actually sight the moon with your thumb as you stretched out your forearm and closed your eye, you would find that it is no bigger at the horizon than it is at it's zenith.
		Martha Croll ===================================================== I believe the correct explanation for the moon appearing larger when it is close to the horizon is a psychological one.
	www.newton.dep.anl.gov /askasci/phy00/phy00711.htm (297 words)

	The Moon Illusion (Site not responding. Last check: 2007-10-11)
		For most people, when they look at the moon on the horizon, it appears larger than it does when it is high in the sky.
		However, the moon is actually the same size in both cases.
		Later on, when the moon is higher in the sky, look at it through the same hole.
	www.dushkin.com /connectext/psy/ch04/moonil.mhtml (301 words)

	Summer Moon Illusion
		The moon is really the same size (0.5 degrees wide) no matter where it appears in the sky--photographs prove it--but the human eye and brain tell us differently.
		When the Moon is rising or setting, distant trees and houses might play the role of Ponzo's converging tracks--they make the moon seem bigger than it is. If so, the moon illusion is simply Ponzo's illusion turned upside down, with the wide bar at the bottom and the narrow bar at the top.
		For example, 'pinch' the moon between your thumb and forefinger or view it through a tube, which hides the foreground terrain.
	science.nasa.gov /headlines/y2002/24jun_moonillusion.htm?list661644 (841 words)

	APOD: 2003 October 11 - Moonrise Over Seattle (Site not responding. Last check: 2007-10-11)
		Oddly, the cause or causes for the common Moon Illusion are still being debated.
		Two leading explanations both hinge on the illusion that foreground objects make a horizon Moon seem farther in the distance.
		In the above time-lapse sequence taken near the end of 2001, the Moon was briefly re-imaged every 2.5 minutes, with the last exposure of longer duration to bring up a magnificent panorama of the city of Seattle.
	antwrp.gsfc.nasa.gov /apod/ap031011.html (187 words)

	Moon Illusion: Explanation
		Inspired by "Measuring the Moon" (a mere puzzle).
		Skeptics know that this is a mere illusion -- that, if anything, the moon ought to appear slightly larger overhead, since it is nearly 4,000 miles closer.
		The use of photography and a rolled-up tube are suggested by several writers for measuring the moon's subtension independent of background (nobody seems to have done what I have done, simply use a mirror to reposition the moon onto the horizon from overhead -- or vice versa -- to counteract the psychological factors).
	www.niquette.com /books/sophmag/moonill.htm (1229 words)

	The Summer Moon Illusion \| MetaFilter
		Go outside and look at the full moon, which will hang in the sky at its lowest point in 18 years over the next three nights, says NASA, creating the "summer moon illusion." If you're a US resident, calculate your local moonrise time here.
		I mean, I'm fully aware of the illusion of the moon looking big when it's close to the horizon, but it's close to the horizon (or "low") EVERY DAY.
		Thus, the northern hemisphere is tilted away from the full moon (remember, the moon is pretty much in the same plane as the sun and earth, so it's roughly equator-level) in the same way as the southern hemisphere is currently tilted away from the sun.
	www.metafilter.com /mefi/42897 (1315 words)

	APOD: 2002 January 30 - Moonrise Over Seattle (Site not responding. Last check: 2007-10-11)
		No -- as shown above, the Moon appears to be very nearly the same size no matter its location on the sky.
		illusion that foreground objects make a horizon Moon seem farther in the distance.
		above time-lapse sequence taken near the end of last year, the Moon was briefly re-imaged every 2.5 minutes, with the last exposure of longer duration to bring up a magnificent panorama of the city of Seattle.
	antwrp.gsfc.nasa.gov /apod/ap020130.html (160 words)

	Have Fun with The Summer Moon Illusion - Local Homeschool.com
		It looks like Earth's moon, round and cratered; the Man in the Moon is in his usual place.
		It includes a very long ladder that reaches to the moon and back and a 4-page centerfold of the full moon that is certain to thrill your preschooler.
		While you're at it, try to think of words that rhyme with the word "moon." For example: room, broom, spoon, zoom, noon, soon, croon, balloon -- and although not spelled the same way -- these words sound the same: June and tune.
	localhs.com /hs/summer-moon-illusion.asp (1361 words)

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