From: jnle@cbnewsd.cb.att.com (C.N.M.T.)
Subject: Re: ANSEWER TO WHY TEHE SUN LOOKS BIG
Organization: AT&T Bell Labs, Naperville, IL USA
Date: Thu, 27 Aug 1992 21:47:47 GMT

In article <1992Aug27.203708.12870@ntmtv>, nguyenpd@ntmtv.UUCP (Phat Nguyen) writes:
> 
> C.N.M.T is only partially right.  His answer is a good guess but it
> has not quite the correct one.  It doesn't explain why the same 'hien
> tuong' also occurs to the moon.  The moon always looks much bigger
> when it is at the horizon than when it is at the top.  If C.N.M.T 
> is right, then it will never happen to the moon because the light
> reflects from the moon is not that great to heat up the 'bau khi
> quyen'.   In fact, at midnight it tends to be colder and more moisture
> in the air than at any other times. Here is my explanations:
> 
> This 'hien tuong' happens because our eyes have been fooled by our
> inability to judge the right distance.  When the moon or the sun
> is at the top, our eyes can perceive the correct distance because
> we are looking at them at a straight line and we know that they
> are far away and we take into account this fact.  In addition,
> there is nothing that stays in our view that makes us interpret
> things differently.  We can correctly judge the right distance
> between the earth and the sun, so the sun and moon looks small
> to us.  On the other hand, when the moon and the sun are at the
> horizon, we cannot judge the right distance and we assume that
> the sun and the moon are much closer to us.  So we interpret that
> they must be much closer, so they look bigger.  Why does this
> phenomenon occur?  Because when they are at the horizon, we can
> only see at most 60 miles from where we stand.  In addition, there
> are other things such as mountain, the surface of the earth, the
> surface of the water, houses, trees and these things are really
> really close to us in term of the distance between the earth and
> the sun.  And it seems to us that the sun or the moon is just
> behind these houses and trees.  So unconsciously, we assume that
> the sun and the moon must be very close to us.  Because we think
> that they are close, our brain interpret them as bigger.  The
> magnifying effect is very very small compared to our own interpretation
> of the relative distance between the earth and the moon.  So it
> says to us that things are not really the way they are, it is
> our own brain that tends to distort things.  In fact, some
> people use this theory to fool the eyes.  I have seen some 3D
> pictures using this technique even though the pictures are 2D
> themselves.  For more info on this phenomenon, refer to the
> researches in THE PSYCHOLOGY OF PERCEPTION.  I happened to
> take this class before and I have tested out all of their
> experiments including some of them that shows how to make
> the moon looks small when it is at the horizon (they do this
> by looking at the moon reflected from the glass holding at
> 45 degree angle.)  Their techniques really work, if you don't
> believe it, you can check out some books on the psychology
> of perception and do the experiments yourself.  So I get
> the right answer, is there any 'Pho?' for me?????
> 
> 
> Nguye^~n Doa~n Pha't
> Northern Telecom
> Mountain View


Wow, a good explanation but ... sorry I have to disagree by what
you said.  If it is our brain's perception that the Sun is bigger
when it is closer to the horizon then it should not fool the camera's
lens, right??  The fact is I can set up my 35mm camera in one spot,
shoot the Sun when it comes up in the morning then again when the
Sun is over our head then compare the pictures, the Sun should be
the same size, right???   BZZZZZZ!!!   Wrong!!! 

I have taken many sunsets/sunrises and in other daytimes and the fact
is the Sun during sunsets/sunrises is STILL bigger than during 
daytimes ... the magnifying effect of the moisture in the air IS the
phenomenon that makes the Sun appear to be bigger to both the naked
eyes and artificial ones ... line of sight to the horizon is ~25-30 
miles and the asmostphere is ~2-mile thick, so in the morning/evening
when the air is cooler and the Sun is closer to the horizon, you are
looking thru ~30 mile thick "magnifier glass" as compared to ~2-mile
thick one at high noon with less moisture in the air ...

I don't know about the trees or buildings that are closer to us that
fool our brain into thinking that the Sun is bigger ...  with the same
logics, I can also lie down on the ground and look at the Sun behind 
the trees and buildings when the Sun is over our head, our brain should
also trick us into thinking that the Sun is closer to us thus it should 
also appear bigger at anytime, right??  How come I don't see the Sun as
bigger then??  Just some thoughts ... :))

About Pho+? .... sure, just buy a ticket to Chicago then I buy you
pho+? .... deal ???  :))

Cheers,
----
C.N.M.T.
Newsgroups: soc.culture.vietnamese