ABOUT THE "MOON
"Believing is Seeing"
MOON ILLUSION: Illusion claimed to exist that moon near
or on the horizon looks "larger" than the moon we recall seeing
high up in the night sky on other occasions.
This illusion has been reported for thousands of years by various
cultures. Usually attributed to clues or perspective from objects seen
on horizon [causing a realization moon is further away than we thought
-- therefore, to be that size of a circle in our eye and be that far away,
it must be larger than we thought.] The realization causes us to "see
"what we realize, or a "believing is seeing" illusion.
The illusion above (which I modified from the Ponzo illusion, shown
later below) seems to work (mildly) based on the amount of area surrounding
the circle -- the more area, the smaller the circle will seem by comparison.
The zenith moon may seem small compared to the vast expanse of sky area
But when I substitute moons in place of the circles, then this is the
The illusion above no longer seems to work. Both moons seem equal sized.
No reason for it comes to mind. So I decided to go back to the original
Ponzo illusion (just below).
- Now here (above) the illusion works -- again only mildly, especially
when I think of the converging lines as being just the letter "V"
that fell over. On that "flat" purely geometric basis, the circles
look practically equal in size. The illusion will pop up, tho', and I think
that's because the eye has trouble completely avoiding the converging lines
as a perspective or distance clue, out of habit or visual programming.
- But again, when I substitute moons for the circles, then it looks like
- Well, now!! It seems that moons here also do NOT create
much of an illusion, or even any illusion, for some reason, but probably
because I'm still seeing the converging lines as a fallen-over letter "V."
- But if I look leftward directly at the "V" and
not the moon, and make myself see it as a perspective thing
going to a vanishing point -- namely, a distance clue -- then the
nearest periphreal moon does look a bit larger. Not as easily
seen as the geometric Ponzo circle picture above this pic, but the illusion
is sometimes there (mildly).
- But now I think, what if I INCREASE the distance clues
-- what if I pictorially FORCE the converging lines to be
a perspective or distance clue totally unable to be perceived as just
a flat fallen-over "V"?
- After I do that, then the illusion should become unquestionably
apparent (scroll down):
- Now the illusion is inescapable. Two moons stuck to a stone wall, one
clearly looking "larger" than the other because it is now
strongly interpreted being on A FURTHER-AWAY part of the wall.
Once again, I have used only a distance clue to create an illusion, or
create a stronger illusion than when objects and lines are
ambiguous in their distance interpretations. When ambiguity about
distance is removed, the illusion doesn't just pop in and out (and
at that, only mildly illusory), but now becomes stable, and even
appears "bigger" in the size of it that is perceived.
- The more that distance is clearly established, the greater size there
is to the illusion. The more cues used for distance, the more the illusion
- Furthermore, the fact that convergence has been turned sideways (unlike
the railroad track illusion which is as used in the illustrations below),
this does not necessarily prevent one from still seeing the illusions.
It may take a few more seconds to kick in, but the distance cues can
even be upside down and still create the illusion of one moon or object
being larger than another (even tho' drawn the same diameters).
- Below, two pics of the moon illusion are created using two methods
of cueing distance to the eye: