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2009-09-30 09:28:03
2009-09-30 09:28:03

The so-called "moon illusion" has nothing to do with atmospheric distortion. The phenomenon can be observed with terrestrial objects, such as mountains or tall buildings (like the Empire State Building), which when viewed at long distances appear much larger than when viewed at closer distances. Here is a fact: the angle subtended by the moon's width when it is near the horizon is THE SAME as when it is directly overhead, even though it appears to be larger when low in the sky. One evening when the moon is low in the sky and appears large, hold your thumb up at arm's length and note the moon's size compared to your thumb. Later, when the moon is high in the sky, do the same thing. You will see that the moon's apparent size does not change. It's a somewhat disturbing experiment, since the data -- your thumb measurements -- defy what your eyes are telling you. Scientists are unsure what causes this phenomenon, but it is obviously related to how the brain interprets images of large, distant objects viewed low in the sky or that appear near the horizon. I observed this phenomenon myself when I visited Seattle for the first time. Mount Rainier, when viewed from Seattle, appears quite huge. It's a big mountain, no doubt, but it appears disproportionately large when viewed from Seattle. As you drive to the mountain, it looms quite large until you get into close proximity, when it doesn't seem quite as massive any longer. Anyone who has been to the New York City area has also observed this phenomenon when viewing the city's skyline from a distance, when the Empire State Building seems preposterously huge. But when the observer gets closer to the city -- say, right across the Hudson near the entrance to the Lincoln tunnel -- the ESB appears only somewhat taller than the other buildings and skyscrapers. answer It's a depth-perception glitch - your mind percieves it as being closer because you are viewing the moon and the relatively closer horizon in the same scope of vision. This is delightful. The moon looks larger at the horizon because it seems farther away. Yes, I know you think I stated that incorrectly. You will see how it works in a moment. Keep in mind the idea stated above of the angle subtended by moon being the same no matter where you see it. Now, when you see the full moon high in the sky, there is nothing readily visible to give you any cues about size or distance. It's just this beautiful white disk floating up there.

Now imagine how we interpret the size of images in our everyday experience. The angle sub-tended by the object is only a part of the picture. Try this "thought experiment". You are in the middle of Death Valley. Your best buddy is standing 100 yards away from you. Get an idea of the size of the image that your buddy makes on your retina. Now imagine a person standing 500 yards from you, but the person is producing the same size retinal imageas your buddy at 100 yards. You know this imaginary person is farther away because you can see that he is nearer to the horizon. The image is a little higher up, so you may even see it against the backdrop of distant mountains. You can see that this person will appear to you to be gigantic. And if he could actually exist, he WOULD be gigantic. But the retinal images for him and your buddy are the same. When we see the moon through trees, or above a horizon of mountains, we have a 'cue' to the distance on this image. The cues tell us: "That thing is far away. And consequently, the brain understands it to be-- Really big...


Related Questions

When the Moon is low on the horizon, there is an optical illusion effect that makes it appear to be bigger than it looks when it is high in the sky. If you were to measure the apparent diameter of the Moon at arms length on the horizon and high in the sky, you would see that they are the same.

Because it was on the night of a full moon.

The Moon's orbit is elliptical; it can be as near to Earth as 240,000 miles and as far as 280,000 miles. Near the horizon, there are atmospheric illusions that make the Moon appear to be larger than it is. The more "full" the Moon is, the bigger it appears to be. When these factors are combined, at the time of the perigee full moon, the Moon can be objectively about 15% larger than normal, and the illusion at Moonrise can make the Moon appear to be enormous. The moon looks different sizes at different times due to the distance apart it is from earth. The further away the moon is from earth the smaller it will look. The closer to earth it is the bigger it will look.

Because it is way closer than other stars!

That actually depends. If you notice a full moon on the horizon, it seems bigger compared to other things on the horizon. When you notice the full moon closer to its zenith in the sky, it seems dwarfed by the vast expance of sky. The difference is an optical illusion.

There are a couple of things at work here. First, there's an optical illusion effect that causes things to appear to be larger when they are close to the horizon. Second, the Moon is in an elliptical orbit; sometimes it is closer than at other times. The "perigee full moon" is actually about 10% bigger than "average".

The moon appears larger because it has different phases. (new moon, waxing crescent moon, etc.)Answer:People often comment that he moon appears larger when it is near the horizon. This is an optical illusion - if you were to cut out a disc of paper the same size as the moon on the horizon and another when it is overhead, the disks would be the same size.This happens because the moon on the horizon can be compared to objects you know are big - distant hills or mountains - and the moon seems bigger than them. Your mind translates this as "The moon is big!". When the moon is high in the sky there is nothing to compare it to, and the mind interprets this as being no particular size at all.A variation on this explanation is that your mind knows the objects on the horizon are far away and are big (but look small) but the moon is "on the horizon" as well and looks big so that it must be even bigger than you thought. Again the high moon has no references and you can't judge size or distance.

The moon is always the same size it may appear bigger because more of the sun's light is shining on it, but no the moon does not "grow" or "shrink".

Mars is always larger than the moon. However, I think you mean will it appear bigger than our moon. No - never - not even close.

All stars are bigger than the moon. Much bigger in fact. Stars only appear small because of their distance from us. The stars are in fact suns, some bigger and brighter than our sun. This gives an idea of how far away they are.

It's an optical illusion, the moon has the same size all the time. It looks bigger near the horizon because we see it compared to trees and buildings.

All stars are bigger than the moon.

Io is a little bigger than the moon :) is bigger than the moon so it has a bigger shadow

Titan is bigger then the moon

the earth is bigger than the moon

Correct. The moon appears larger than the stars because it is much closer to us.

Neptune is bigger than moon mass of Neptune = 1.0244 × 1026 kilograms mass of the Moon = 7.36 × 1022 kilogramstune is bigger than moon

Pluto is the planet that has a moon bigger than itself.

No planet has a moon bigger than itself.

Stars are much bigger than the Moon, is the answer to 'Are stars bigger THAN the moon?' But your question doesn't make sense.

If you look at the moon when it's full, you'll see that it appears bigger when it's near the horizon, but appears to shrink as it ascends in the sky. It's an illusion. When the moon is partially obscured by some trees, our brains compare the sizes and make the moon appear larger than when it's higher in the sky and nothing is blocking it.

no pluto is not bigger, it is the smaller the moon is bigger

Stars are much bigger than the Moon.

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