Why sun looks bigger in the evening?

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Discussion Overview

The discussion revolves around the perception of the sun appearing larger in the evening compared to noon, despite its actual distance from the Earth. Participants explore various explanations and observations related to this phenomenon, including optical illusions and physiological effects.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants suggest that the perceived size of the sun in the evening is similar to the Moon illusion, where the presence of foreground objects influences perception.
  • One participant notes that lying on the ground can alter the perception of distance for overhead objects, although this is met with humor and personal anecdotes.
  • Another participant mentions the role of the eye's physiology and visual processing in creating a magnified image of objects in the center of the field of view.
  • Refraction is proposed as a potential factor that could magnify the image of the sun, although this is challenged by another participant who argues that looking straight up minimizes atmospheric effects.
  • A later reply emphasizes that the perceived size is an illusion rather than a physical change in size.
  • One participant humorously suggests that if someone is close enough to notice the sun's size, they should consult an eye doctor.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the reasons behind the sun's perceived size, with no consensus reached on a definitive explanation.

Contextual Notes

Some claims depend on individual perceptions and experiences, and the discussion includes references to optical illusions and physiological aspects of vision that may not be universally applicable.

En_lizard
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why sun looks bigger in the evening? although it's closer to the Earth during noon?
 
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It's not significantly closer to Earth during noon. Your eye could never percieve the difference.

I would have to guess its for the same reason as the Moon illusion. When the Moon is low, you have foreground to compare it to. That sets up an optical illusion that deceives you into thinking that it is bigger.

The Moon's horizon and overhead distances are slightly greater than insignificant, with it being bigger overhead. But the difference is still small enough that the optical illusion overwhelms it.
 
One thing I've noticed is that if you lie on the ground looking straight up at the sky, things overhead (clouds particularly) look closer than when you are standing up.
 
mathman said:
One thing I've noticed is that if you lie on the ground looking straight up at the sky, things overhead (clouds particularly) look closer than when you are standing up.
I believe that only happens because you (any person) are on the ground looking up from being too stoned to stand...:smile:
 
I believe that only happens because you (any person) are on the ground looking up from being too stoned to stand...
Didn't you ever picnic in the park with your girl friend?
 
mathman said:
Didn't you ever picnic in the park with your girl friend?
Yes, many times but I don't recall ever looking UP.
:biggrin: ..:biggrin: ..:biggrin:
 
mathman said:
One thing I've noticed is that if you lie on the ground looking straight up at the sky, things overhead (clouds particularly) look closer than when you are standing up.
This is true. If you will Google on fovea, you will see how the non-uniformity in the eye and the non-uniformity in the visual cortex work together to give us a magnified and sharpened image in the center of our field of view. This effect is especially pronounced in birds of prey, who often have to locate their food from very high up.
 
In a word, refraction. The Earth's atmosphere magnifies the image.
 
Labguy said:
Yes, many times but I don't recall ever looking UP.
:biggrin: ..:biggrin: ..:biggrin:


Thats just a function of positioning.
 
  • #10
Chronos said:
In a word, refraction. The Earth's atmosphere magnifies the image.
Not enough for you to notice, and the effect is in the wrong direction, anyway. When you are looking straight up, you are looking through the least amount of atmosphere possible. The apparent largeness and sharpness of things in the center of our field of view is due to the physiology of the eye and to the manner in which the eye is wired to the visual cortex.
 
  • #11
Turbo is correct, it's an illusion:
http://facstaff.uww.edu/mccreadd/sectionIII.html
 
Last edited by a moderator:
  • #12
En_lizard said:
why sun looks bigger in the evening? although it's closer to the Earth during noon?

If you're looking at the sun close enough to notice this, you should see an eye doctor.
 

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