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Posers and Puzzles

Posers and Puzzles

  1. Standard member wolfgang59
    Infidel
    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. Standard member 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. Subscriber coquette
    Already mated
    31 Aug '07 14:51 / 2 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. Subscriber AThousandYoung
    Proud Boys Beware
    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 20:46 / 1 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. Subscriber coquette
    Already mated
    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. Subscriber coquette
    Already mated
    31 Aug '07 23:54
    of course i do, it's not just a theory
  9. Standard member 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.
  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. Standard member 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. Subscriber sonhouse
    Fast and Curious
    07 Sep '07 00:47 / 1 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. Standard member 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.

    Check this link: http://www.lhup.edu/~dsimanek/3d/moonillu.htm
  15. 07 Sep '07 06:56 / 1 edit
    Originally posted by HandyAndy
    A similar illusion is true of the rising and setting sun.

    Check this link: http://www.lhup.edu/~dsimanek/3d/moonillu.htm
    You hint that the same illusion is valid by the sun too. And that hint is valid!

    What seems to be the larger:
    (1) The rising moon or the setting moon?
    (2) The rising sun or the setting sun?
    And why is it so?

    Has this anything to do with astronomy, or geometry? Or is it only a matter of psycology and perception?