Moon question

wolfgang59
Posers and Puzzles 31 Aug '07 10:01
1. wolfgang59
Mr. Wolf
31 Aug '07 10:01
Why does the moon look substantially larger when close to the horizon than at its zenith?

I dont know the answer and something more detailed than "its an optical illusion" would be nice!
2. Palynka
Upward Spiral
31 Aug '07 10:15
Originally posted by wolfgang59
Why does the moon look substantially larger when close to the horizon than at its zenith?

I dont know the answer and something more detailed than "its an optical illusion" would be nice!
Here's an interesting explanation. I particularly like this part

http://www.straightdope.com/classics/a2_110.html

What's now called the "apparent distance" theory was first advanced by the Egyptian astronomer Ptolemy in the second century AD (I told you this goes back a ways). His explanation is a little confusing, but here goes: most people subconsciously perceive the sky to be a flattened bowl--i.e., objects near the horizon seem farther away than objects overhead, due to the abundance of intervening visual cues on the ground. Now, when we see an image of a certain size at what we believe is a great distance, we deduce that it's bigger than an image of the same size seen at what seems to be a lesser distance. (You might want to let this percolate for a minute.) So when we see the moon at the "distant" horizon, we subconsciously conclude that that it's "bigger" than when we see it a few hours later overhead, when it's "close." To put it another way, perspective--i.e., the march of visual cues to the horizon--makes the the moon look bigger than it does when it's just hanging in space.
3. coquette
31 Aug '07 14:512 edits
Originally posted by wolfgang59
Why does the moon look substantially larger when close to the horizon than at its zenith?

I dont know the answer and something more detailed than "its an optical illusion" would be nice!
maybe you are confusing "illusion" with "delusion"

the optical illusion is very real and is based on the way our brains interpret the physical world around us. note that your questions says, "why does the moon APPEAR larger" not "why is the moon ACTUALLY larger" which, of course, it isn't. in fact, as pointed out above, it is actually somewhat smaller due to being more distant by the radius of the earth, as previously stated, and, just a little bit vertically elongated by the lens effect of the atmosphere, but still, the same size as far as our eyes physically process the image at the retina.

So, what would be a delusion? that would be believing that the cow actually jumped over the moon - very possible - if the moon is setting on the horizon! still, the cow, while jumping, and the moon, while setting, and you while sitting there pondering the larger size of the moon and believing that there is more to it all than an optical illusion, happens to believe that the cow actually did jump over the moon while the moon was growing larger and that he is actually in love with you at that moment and you will live happily ever after.

wait. i think the moon gets bigger. the cow did jump over the moon. and he really did love me. life just had to go on, i suppose. oh well. forget it. i don't know either.
4. AThousandYoung
31 Aug '07 15:08
Originally posted by wolfgang59
Why does the moon look substantially larger when close to the horizon than at its zenith?

I dont know the answer and something more detailed than "its an optical illusion" would be nice!
Because your eyeballs shrink around that time.
5. 31 Aug '07 20:461 edit
Another question:

Does the rising moon appear smaller or larger than a setting moon?

Edit: with 'moon' I mean 'full moon'. It may make a difference.
6. coquette
31 Aug '07 21:07
Originally posted by FabianFnas
Another question:

Does the rising moon appear smaller or larger than a setting moon?
yes
7. 31 Aug '07 21:09
Originally posted by coquette
yes
Oh, you think so too? Then you back my theory?
8. coquette
31 Aug '07 23:54
of course i do, it's not just a theory
9. smw6869
Granny
01 Sep '07 18:07
Originally posted by Palynka
Here's an interesting explanation. I particularly like this part

http://www.straightdope.com/classics/a2_110.html

What's now called the "apparent distance" theory was first advanced by the Egyptian astronomer Ptolemy in the second century AD (I told you this goes back a ways). His explanation is a little confusing, but here goes: most people subcons ...[text shortened]... --makes the the moon look bigger than it does when it's just hanging in space.
This, my friend, is mumbo jumbo. The moon affects the ocean tides. When the moon first appears on the horizon the tides retreat, and where does the water go?....into the moon, thus making the moon actually larger when at the horizon. When the moon is straight over head it can no longer hold onto the water ,and releases it back to the oceans and thus the rise in tides at that time and the actual shrinking of the moon. Case closed. It's just a case of logical reasoning.
10. 01 Sep '07 19:25
Originally posted by smw6869
This, my friend, is mumbo jumbo. The moon affects the ocean tides. When the moon first appears on the horizon the tides retreat, and where does the water go?....into the moon, thus making the moon actually larger when at the horizon. When the moon is straight over head it can no longer hold onto the water ,and releases it back to the oceans and thus the rise ...[text shortened]... time and the actual shrinking of the moon. Case closed. It's just a case of logical reasoning.
ðŸ˜€
11. 02 Sep '07 16:19
Originally posted by FabianFnas
Oh, you think so too? Then you back my theory?
Isn't there anyone who knows the difference between appearance of a rising full moon compered by the one of a setting full moon?

(hint) other than the rising is at the east and the setting is at the west horizon?
12. smw6869
Granny
06 Sep '07 02:14
Originally posted by FabianFnas
Isn't there anyone who knows the difference between appearance of a rising full moon compered by the one of a setting full moon?

(hint) other than the rising is at the east and the setting is at the west horizon?
Another easy one. When the moon is rising the American flag, that was put there in 1969, is upside down. When the moon is setting the flag is in the upright position.
13. sonhouse
Fast and Curious
07 Sep '07 00:471 edit
Originally posted by coquette
maybe you are confusing "illusion" with "delusion"

the optical illusion is very real and is based on the way our brains interpret the physical world around us. note that your questions says, "why does the moon APPEAR larger" not "why is the moon ACTUALLY larger" which, of course, it isn't. in fact, as pointed out above, it is actually somewhat smaller du ...[text shortened]... d love me. life just had to go on, i suppose. oh well. forget it. i don't know either.
I wonder what the brain would do if confronted by putting a pair of calipers just clipping the sides of the moon when at its highest and then taking those calipers and locking them in place, then when the moon sets on the horizon, you put the calipers around the moon again. Would the brain see that the calipers should clip the same angle of the moon and be at the edges or would we see the calipers cutting off some of the moon? We would assume you would view the calipers at the same distance each time, like your arms length or something.
14. HandyAndy
Non sum qualis eram
07 Sep '07 02:51
Originally posted by wolfgang59
Why does the moon look substantially larger when close to the horizon than at its zenith?

I dont know the answer and something more detailed than "its an optical illusion" would be nice!
A similar illusion is true of the rising and setting sun.