Why the moon looks bigger at the horizon

[PhanthomJay]

If I did the same experiment a very long (undetermined) distance away, using discs, which gave no indication of their actual size, you would have absolutely no clue which one I was showing you.

I'm sorry about your losing your sense of humor. If it was because of me, I apologize. I would have thought that years of dealing with my kind would have brought you patience.

Let me ask you this: Supposing you were a cave man on Planet X. There were 2 moons orbiting your planet of unknown size and at an unknown distance away. Moon A and Moon B. When orbiting side by side, you notice, by comparison, that one (Moon A) is much much much much larger than the other (Moon B). Now sometime later, Moon B has taken off to parts unknown, and it no longer appears in the sky. Only Moon A remains. Would you know that the remaining moon is Moon A, or would you not know? Assume that no other moon has come into existence, so that the remaining moon must be either moon A or Moon B. Could you tell, without having both moons present to make the call?

 

[DaveC426913]

Supposing you were a cave man on Planet X. There were 2 moons orbiting your planet

Do you think some warning flags should be going up if the scenarios have to get this contrived?

 

[PhanthomJay]

Do you think some warning flags should be going up if the scenarios have to get this contrived?

I did take an extreme example, but since we are at an impasse, let me compromise by saying this:

"Once upon a time, not too long ago, I saw a really really big moon. Or at least I thought I saw it...perhaps, instead, time has rewritten every line. But, whether real or imagined, it makes no difference, for one time, not too long ago, I saw a huge appearing moon, and its memory will stay with me forever."

 

[DaveC426913]

I did take an extreme example, but since we are at an impasse, let me compromise by saying this:

"Once upon a time, not too long ago, I saw a really really big moon. Or at least I thought I saw it...perhaps, instead, time has rewritten every line. But, whether real or imagined, it makes no difference, for one time, not too long ago, I saw a huge appearing moon, and its memory will stay with me forever."

I can live with that.

 

[PhanthomJay]

I can live with that.

Great, thanks, I'm glad this is over! So is my wife...she thinks I spend too much time on this forum, and looking at the moon, and not enough time helping around the house. And I'll have to admit, she's probably right.

Thanks for your valued input.

 

[DaveC426913]

Great, thanks, I'm glad this is over! So is my wife...she thinks I spend too much time on this forum, and looking at the moon, and not enough time helping around the house. And I'll have to admit, she's probably right.

Thanks for your valued input.

It is a calling for me too.


You keep watching those skies Phanthom.

Wherever you go, I'll be there.


I am.

Anti-PhanthomJay.

 

[PhanthomJay]

It is a calling for me too.


You keep watching those skies Phanthom.

Wherever you go, I'll be there.


I am.

Anti-PhanthomJay.

Looks like you'll be back in the running for the 2010 Best Humor Award!

 

[raylphscs]

I still think the illusion theory is wrong. It is aparently the optical lenz effect of the spherical atomsphere acted like a telescope. when the moon is near the horizon, it not only looks big, but you can see much details on its surface like the dark areas and dark spots. If a brain illusion caused the moon seem big, there should be no more details to be seen, only size bigger.
Illusion theory is wrong and is not scientific.

 

[D H]

Read the thread, raylphscs. There is a tiny atmospheric effect near the horizon. This tiny effect does not explain the Moon illusion for two reasons. (1) The effect is tiny. We perceive the Moon to be considerably bigger near the horizon compared to when it is overhead. (2) The atmospheric effect makes the apparent size of the Moon a tiny bit smaller when the Moon is near the horizon.

 

[Brin]

I still think the illusion theory is wrong. It is aparently the optical lenz effect of the spherical atomsphere acted like a telescope. when the moon is near the horizon, it not only looks big, but you can see much details on its surface like the dark areas and dark spots. If a brain illusion caused the moon seem big, there should be no more details to be seen, only size bigger.
Illusion theory is wrong and is not scientific.

Wow. I propose a new rule after reading this entire freakin' thread: Quantitative results. Go get your 'lenz effect of the spherical atmosphere acted like a telescope' equations and get to work. It's not that hard. I think it's like chapter 34 or something in Young and Freedman.

Calculate precisely how large the moon should appear under each of the conditions being proposed. Post them here if they are significantly different (not the 12% we know about already).

 

[JDługosz]

I still think the illusion theory is wrong. It is aparently [sic] the optical lenz effect of the spherical atomsphere [sic] acted like a telescope. when the moon is near the horizon, it not only looks big, but you can see much details on its surface like the dark areas and dark spots. If a brain illusion caused the moon seem big, there should be no more details to be seen, only size bigger.
Illusion theory is wrong and is not scientific.

Wrong, wrong, and wrong. The illusion theory is scientific because the actual angular size can be measured with scientific instruments. It is actually a tiny bit smaller at the horizon, so appearing larger is an illusion. I for one don't see more details when it is low, other than the phycological effect of being able to look at it for a while rather than just glance at it. If you stare at the high moon for a bit, it will seem to "expand" in your attention to fill your gaze. A low red moon might have different contrast than a high white moon. If you calculate the effect you site, you'll find it does not match your assertions.

 

[raylphscs]

Same angular size behind different lenz, meaning different image size! This was what the illusion theory ignored.! The so called experiments forgot the fact that there are different lenz between the moon and the observer when the moon is at different altitude. ! Why people don't consider everything involved when doing experiment? So end up with erroneous conclusion?
when we see objects on the other side of a lenz, the image looks different size if the lenz change shape, this is scientific, it is not illusion, it is the light rays bent causing the image size change. It is not any illusion causing the horizontal moon looks big. The moon image size change is because the atomosperic lenz shape changed between the moon and observer when the moon change altitude. If there were no atomasphere on earth, the moon image would never change size no matter on the horizon or above our head!

 

[Brin]

I'm guessing you haven't heard of "spherical symmetry?"

Seriously. Get a pad of paper, and draw the LENS. Show us the difference!

 

[DaveC426913]

Same angular size behind different lenz, meaning different image size! This was what the illusion theory ignored.! The so called experiments forgot the fact that there are different lenz between the moon and the observer when the moon is at different altitude. ! Why people don't consider everything involved when doing experiment? So end up with erroneous conclusion?
when we see objects on the other side of a lenz, the image looks different size if the lenz change shape, this is scientific, it is not illusion, it is the light rays bent causing the image size change. It is not any illusion causing the horizontal moon looks big. The moon image size change is because the atomosperic lenz shape changed between the moon and observer when the moon change altitude. If there were no atomasphere on earth, the moon image would never change size no matter on the horizon or above our head!

raylphscs, you have not thought this through. As previously pointed out, the effect of atmospheric lensing will actually serve to decrease the apparent diameter of the Moon.

And please stop screaming about being scienitific. The only one not being scientific here is you. You've got an idea stuck in your head that you haven't examined and won't let go of.

 

[raylphscs]

I'm guessing you haven't heard of "spherical symmetry?"

the atomasphere is symetrical to the center of the earth, but you are on the surface of the earth, it is not spherically symetrical to you. you are too far away from the center of the earth.

 

[rustynail]

@raylphscs:

You know that the moon revolves around the earth, and does not actually "change altitude", right?

 

[Brin]

the atomasphere is symetrical to the center of the earth, but you are on the surface of the earth, it is not spherically symetrical to you. you are too far away from the center of the earth.

Draw a picture, do the numbers. Read the thread. I'm done here.

 

[raylphscs]

As previously pointed out, the effect of atmospheric lensing will actually serve to decrease the apparent diameter of the Moon.

This was wrong, you pointed out doesn't mean it be the truth. while the moon near the horizon, the atomsphere lenz serves to enlarge the image. while it is above head, the atomosphere lenz changed shape and causing different image size.

 

[raylphscs]

As previously pointed out, the effect of atmospheric lensing will actually serve to decrease the apparent diameter of the Moon.

This was wrong, you pointed out doesn't mean it be the truth. while the moon near the horizon, the atomsphere lenz serves to enlarge the image. while it is above head, the atomosphere lenz changed shape and will decrease the image size.C:\Users\owner\Documents\moon_earth_atomosphere.jpg

 

[raylphscs]

@raylphscs:

You know that the moon revolves around the earth, and does not actually "change altitude", right?

By "altitude" I mean how close to the horizon, don't go by the literal meaning please

 

[rustynail]

By "altitude" I mean how close to the horizon, don't go by the literal meaning please

Using correct words along with their correct acception just seems to be a good way to be understood. But just because I pointed out doesn't mean it be the truth...

 

[raylphscs]

QUOTE=Brin;2959610]Golly gee, you're thick.
Draw a picture, do the numbers. Read the thread. I'm done here.[/QUOTE]

please the analogy picture

[

 

[D H]

Your picture doesn't show your purported atmospheric effect. It cannot for the simple reason that your purported effect doesn't exist. The atmosphere does not act as a lens that magnifies the size of the Moon.

Aside: The word is lens, not lenz. Most browsers have spell checkers and highlight misspelled words. Mine, for example, shows "lenz" with a red underscore. That means that "lenz" is not a word.

Back on topic: Using the well-known equation 1 picture = 1000 words, here is a several thousand word essay on this topic:

Source: http://antwrp.gsfc.nasa.gov/apod/ap020130.html

Source: http://spaceweather.com/submissions/large_image_popup.php?image_name=Chris-Picking-moon_rising_composite_1213915516.jpg
[PLAIN]http://spaceweather.com/submissions/pics/c/Chris-Picking-moon_rising_composite_1213915516_med.jpg

Source: http://greenmanblog.com/archives/P87.html
http://greenmanblog.com/uploads/FullMoons.jpg

Source: http://epod.usra.edu/blog/2007/06/rising-moon-illusion.html
[URL]http://epod.typepad.com/.a/6a0105371bb32c970b011571a50254970b-600wi[/URL]

 

[sophiecentaur]

Smashing pictures! And they should be proof enough for anyone.

I haven't trawled the whole way through this thread but I always thought that the reason was almost totally subjective. The brain does its best to estimate things but often does a pretty poor job. Out on its own, the moon is just an unimportant blob of light and the brain doesn't give it much significance. When you see it going down behind a massive building, tree or hill, you realize just how big it is in context.

You get a similar effect when looking up at the top of a ladder from the ground and then looking at the ground from the top of the ladder. I reckon at least two to one subjective difference! I never get vertigo looking up at a ladder. Context is everything.

Of course, the Moon's distance varies significantly over the year and it sometimes really does subtend a bit 'bigger' angle at times. That's not an illusion.

 

[DaveC426913]

please the analogy picture

[

OK, now show how it leads to the effect you describe.

 

[JDługosz]

You get a similar effect with traffic lights. If you see one on the ground with people working on it, it seems much larger than you expected. They can be as tall as a man, so 5 or 6 feet. But in their normal location they seem small.

 

[DaveC426913]

You get a similar effect with traffic lights. If you see one on the ground with people working on it, it seems much larger than you expected. They can be as tall as a man, so 5 or 6 feet. But in their normal location they seem small.

Huh. Never thought of that. Cool.

 

[txd453]

I'm just curious, I've never tried this or heard of it being used, but... is it possible to use a micrometer or a set of calipers (dial calipers for example) held a set distance from the observer's eye, to make size estimates? Would that be a more quantitative way of doing it, rather than using a dime or a pencil eraser?

 

[DaveC426913]

I'm just curious, I've never tried this or heard of it being used, but... is it possible to use a micrometer or a set of calipers (dial calipers for example) held a set distance from the observer's eye, to make size estimates? Would that be a more quantitative way of doing it, rather than using a dime or a pencil eraser?

Uh. Sure.

Why?

Do you doubt the likelihood that the effect is as mentioned? Do you question the pictures above?

 

[pallidin]

You get a similar effect with traffic lights. If you see one on the ground with people working on it, it seems much larger than you expected. They can be as tall as a man, so 5 or 6 feet. But in their normal location they seem small.

Uh, a standard traffic light is about 41 inches tall. Just a little over 3-feet.

Source: http://answers.yahoo.com/question/index?qid=20070322180304AArkOTp

 

[D H]

Uh, a standard traffic light is about 41 inches tall. Just a little over 3-feet.

Source: http://answers.yahoo.com/question/index?qid=20070322180304AArkOTp

Gotta love those bad answers at answers.yahoo.com!

That 41 inch figure is not the "standard traffic light" size. That size is the size of an older traffic light used at the intersection of two low-speed roads. Those signals use 8 inch diameter signal lenses. Traffic light lenses in the US come in two sizes: 8 inch (200 mm) and 12 inch (300 mm). Those older 8 inch diameter lights are being phased out. Those 12 inch diameter signal lights are the mandated size for new vehicular traffic signals except at the intersection of two small low-speed road (Manual on Uniform Traffic Control Devices, section 4D.07).

Some traffic signals have a vertical stack of five lights, the standard red/yellow/green plus two more for protected turn lanes. At 14 inches per light plus 8 inches top and bottom, those signals are over 7 feet tall. A simple three light (red/yellow/green) signal with 12 inch diameter lenses is just shy of 5 feet tall.Back to the moon illusion discussion ...

 

[Redbelly98]

Back to the moon illusion discussion ...

No! Pleeeease, anything but that!

I'm just curious, I've never tried this or heard of it being used, but... is it possible to use a micrometer or a set of calipers (dial calipers for example) held a set distance from the observer's eye, to make size estimates? Would that be a more quantitative way of doing it, rather than using a dime or a pencil eraser?

Yes, certainly. Just be careful about holding the calipers the same distance away for both measurements, which would be done several hours apart.

Uh. Sure.

Why?

Do you doubt the likelihood that the effect is as mentioned? Do you question the pictures above?

But questioning, and verifying with measurement, is how science gets done. Whether it's researchers on the cutting edge, or students and nonprofessionals trying to learn what is already known by professionals.

 

[sophiecentaur]

But questioning, and verifying with measurement, is how science gets done. Whether it's researchers on the cutting edge, or students and nonprofessionals trying to learn what is already known by professionals.

True but your alternative measurement needs to be valid. What you describe, on its own, may well not be.

Edit - I'm not sure who I am replying to, actually but my point stands.

 

[sophiecentaur]

I still think it's amazing that a piece of green cheese can look so different as it moves around the sky.

 

[pallidin]

My bad, DH, thanks for the clarification.

 

[txd453]

I'm just curious, I've never tried this or heard of it being used, but... is it possible to use a micrometer or a set of calipers (dial calipers for example) held a set distance from the observer's eye, to make size estimates? Would that be a more quantitative way of doing it, rather than using a dime or a pencil eraser?

Uh. Sure.

Why?

Do you doubt the likelihood that the effect is as mentioned? Do you question the pictures above?

True but your alternative measurement needs to be valid. What you describe, on its own, may well not be.

Edit - I'm not sure who I am replying to, actually but my point stands.

Maaan, y'all are a touchy bunch! :=) The statement prior to the question was literal, I'm just curious; and the photos are definitive. However, I don't see how the 'alternative measurement' would be less valid than using a dime or a pencil eraser. What would be the sources of error? It should be fairly easy to rig something to reduce the variability in the distance between the calipers and the observer's eye...

 

[D H]

A pencil eraser would work just fine for this, maybe a grease pencil if you have long arms.

A dime will work if you want something more precise. You will need some device to hold the dime about 2 meters away from your eyes however.

 

[DaveC426913]

Maaan, y'all are a touchy bunch! :=)

That's the way we roll here. You want the Wishy Washy Forum of Fluffy Guesses, that's next door.

 

[MagnetDave]

Can we enshrine this thread in the Cranial Density Hall of Fame?

Any time we are discussing something sophisticated with someone who refuses to understand, can we just say cite the Moon Principle: No evidence can be so irrefutable as to overcome all desire to not be wrong? Sort of a scientific Godwin's Law, when the argument has been explained with the maximum possible clarity, therefore consuming all value in the discussion...

Agree?

 

[DaveC426913]

I feel strangely attracted to you...

 

[txd453]

In defense of PhantomJay, there are two aspects to this question: physics and perception, which is clear from the very beginning of the discussion. With all due respect, the back-&-forth with PJ over harvest moons has focused almost solely on the physics (astronomy) side of the question. However, the only way to completely answer his question is to do something like the following: set up a realistic-looking simulator that reproduces the effect and has the ability to vary the size of the (bogus) moon. Get a plot of (simulated) real size (angular diameter) vs. (simulated) apparent size. Locate the (real, un-simulated) lunar size on the plot under various conditions (e.g. apogee & perigee), and compare the ratios of the corresponding apparent sizes. You could even do a statistical study of person-to-person variation.

 

[MagnetDave]

The analogy is "some people think the sky is purple." If everyone answers to the effect of "the sky is blue, here are the physics of the radiation spectrum, and the eye's perception of color, and the net result is 'blue' as defined by common functions" and one person comes in with "I saw a sky a few years ago I thought was really periwinkle," the solution is not to then blue a phantom sky, experimentally slice out the colors and poll every possible person.

There is really no reasonable basis for this to be a nine-page thread apart from sheer stubbornness. If I make a subjective observation of an objective fact, and am presented with evidence that my observation is accounted for by known phenomena, the correct response is NOT to then say, "No, my observation was much huger, and I can't understand why no one else sees this" and then grasp for an explanation, ignoring every reasonable thing that is said for five more pages, and then get upset that people are annoyed with me on the sixth. The apogee/perigee issue was resolved in the first answer at "15% longer," yet he continually ignored that people were taking area into account in the hopes of justifying his "one and half times bigger" observation. We went into explanations about telephoto lens - and zoom lenses got mixed in there.

If *I* make a subjective observation and everyone can explain it, at some point, I have to say, "huh, guess I must have seen it funny," because it was a _subjective_ observation. I don't see why we have to die on this hill. If I observed "the moon occupied x arc-minutes of sky on this day and 1.5x arc-minutes of sky on that day, then yeah, I stand by it. But I also explain my methods, and expose my experiment so we can see if I have an error.

Otherwise, we are just a bunch of guys arguing why a hammer falls faster than a feather with some guy who insists that gravity is different.

 

[PhanthomJay]

https://www.youtube.com/watch?v=

The apogee/perigee issue was resolved in the first answer at "15% longer," yet he continually ignored that people were taking area into account in the hopes of justifying his "one and half times bigger" observation.

I'm glad you enjoyed all 9 pages and then some of the thread! I did not want to bring this topic up again until the special night of March 21, 2011 (mark it now on your calendar), when the moon, near the date of the Vernal equinox, will be nearly full, rise after sunset, and be at near Perigee. But I am forced to rebut your criticism.

The moon at Perigee is about 45,000 km closer to us than when it is at apogee, so it will appear about near 12 % larger in diameter (about 25 % larger in projected surface area) than when at apogee. This is a known fact. But it is difficult to note this increase without a side by side comparison. But also a known fact is the 'Moon Illusion' effect, when the brain makes the moon appear larger when on the horizon. This can be proven by looking through a tube thru one eye, and without a tube through the other eye, and make the side by side comparison. How much larger? I don't know, pick a number, let's just say 'larger'.

Now the combination of the Moon Illusion on the horizon and the fact that the full moon will be at Perigee as it rises on the horizon after sunset on 21 March, will produce an apparent size of the moon that will be very large indeed, I imagine, even without a side by side comparison to a full overhead moon at apogee ...what do you think? I had overlooked this in my earlier postings, until it was definitively pointed out to me that the Harvest Moon was at Apogee, which made the vision a bust. Sorry about that.

Save the date: 21 March, 2011...back to square 1.

 

[JDługosz]

I'm just curious, I've never tried this or heard of it being used, but... is it possible to use a micrometer or a set of calipers (dial calipers for example) held a set distance from the observer's eye, to make size estimates? Would that be a more quantitative way of doing it, rather than using a dime or a pencil eraser?

I think an easy way to do it would be to take a tube like from a roll of paper towels, and put a transparent cover on one end upon which is drawn a scale.

You'll find that if you focus on the moon, the marks on the scale are out of focus, and vice-versa. But it will put some boundary on the measured size. Use a longer tube to get sharper measurements.

Furthermore, if the moon clears the horizon and other objects by enough of a margin, the tube can isolate your view and interfere with the illusion, showing you clearly that it is perception.

 

[raylphscs]

While the atmosphere does have some effect on the Moon near the horizon, it isn't what you think it is. For one, the index of refraction for air is pretty small (1.0003), For the Other the effect it does have is to bend light slightly around the horizon, so that we see objects that, in a straight line, are below the horizon and objects just at the horizon are seen higher in the sky. This bending effect gets stronger as your line of sight nears the horizon. When the Moon is sitting right at the Horizon, the effect is stronger at the bottom of the Moon than it is at the top, so the actual effect is to "flatten" the Moon slightly, not enlarge it.

The moon is so far away, 1.0003 multiply by the distance between the moon and earth, it will make the moon image size substantially bigger.

 

[cjl]

The problem with your line of argument is that it is already conclusively proven wrong (just look at the pictures posted a few posts back).

 

[raylphscs]

Your picture doesn't show your purported atmospheric effect. It cannot for the simple reason that your purported effect doesn't exist. The atmosphere does not act as a lens that magnifies the size of the Moon.

Aside: The word is lens, not lenz. Most browsers have spell checkers and highlight misspelled words. Mine, for example, shows "lenz" with a red underscore. That means that "lenz" is not a word.

Back on topic: Using the well-known equation 1 picture = 1000 words, here is a several thousand word essay on this topic:

Source: http://antwrp.gsfc.nasa.gov/apod/ap020130.html

Source: http://spaceweather.com/submissions/large_image_popup.php?image_name=Chris-Picking-moon_rising_composite_1213915516.jpg
[PLAIN]http://spaceweather.com/submissions/pics/c/Chris-Picking-moon_rising_composite_1213915516_med.jpg

Source: http://greenmanblog.com/archives/P87.html
http://greenmanblog.com/uploads/FullMoons.jpg

Source: http://epod.usra.edu/blog/2007/06/rising-moon-illusion.html
[PLAIN]http://epod.typepad.com/.a/6a0105371bb32c970b011571a50254970b-600wi[/QUOTE]

how was the picture taken? it means everything. where is the scale for time?? what are the different times for each picture?

 

[DaveC426913]

how was the picture taken? it means everything. where is the scale for time?? what are the different times for each picture?

While that would all be interesting information, it wouldn't change anything.

And it can be deduced. Unless you have reason to suspect that the Moon has recently changed how fast it moves across the sky.

 

[D H]

how was the picture taken? it means everything. where is the scale for time?? what are the different times for each picture?

That information regarding the first two photos is right there in the links I provided.

That said, it is rather obvious how those pictures were taken. The first three are time-lapsed multiple exposures while the fourth is a single long exposure. The advantage of the first three is that you can clearly see the horizon and clearly see that the atmosphere does not magnify the size of the Moon. The advantage of the fourth is that you can see nice parallel lines (in other words, the atmosphere does not magnify the Moon).

Surely you have looked elsewhere on the 'net by now and found a vast number of sites that discuss the Moon illusion. If you haven't do so: Google the phrase "moon illusion" and read some of the many links provided.

Wondering how and why our minds are so thoroughly tricked so much is a valid question. Insisting that the phenomenon is real rather than an illusion is not valid. While you are entitled to your own opinions, you are not entitled to your own facts.

 

[Janus]

The moon is so far away, 1.0003 multiply by the distance between the moon and earth, it will make the moon image size substantially bigger.

This argument makes no sense what-so-ever. The distance to the moon doesn't factor into this. The refractive index determines the difference between the angle at which the light enters the atmosphere and it has after it has entered.

If you go back to post #24, I show the effects of no atmosphere to normal atmosphere and thicker than normal atmosphere.
Those images were done with Ray-tracing software. How this works is that you define the positions of a camera, light source(s) and object(s) in a three dimensional space. The software will then calculate the path of light rays leaving the light source, bouncing off of any objects in the scene and determine which would enter the camera. The objects in the scene can be assigned characteristics such as color, finish, transparency etc.
One of the characteristics that can be applied to transparent objects is index of refraction. When tracing a ray, the software will take into account any IOR assigned to an object and deflect the ray accordingly. For example, the attached image was created with the ray-tracer. It shows two "glass" spheres sitting on a checkered plane. The left sphere has had its index of refraction set to 1, while the right one has its set to 1.5

For the images in post #24, I did this:
I created two spheres with their sizes relative to each other being the same as that of the Earth to the Moon.
I placed the smaller sphere at a distance away from the first that corresponded to the
distance of the Moon from the Earth.
I placed the "camera" at a point on the surface of the large sphere so that the smaller sphere appeared at its horizon.
The software rendered the image that the camera would see. This was the view with no atmosphere.

I created a transparent "shell" around the larger sphere with the same relative thickness and index of refraction of our atmosphere.
The software rendered the new image that the camera would see under these conditions.

I increased the index of refraction for the "atmosphere" to increase any effect and had the software render the new image.

The images created were what the software calculated what the camera would see under the different conditions of no atmosphere, normal atmosphere and thick atmosphere. This showed that there is no noticeable difference between atmosphere and no atmosphere, and debunked the idea that atmospheric refraction has any perceptual effect on the apparent size of the Moon.