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I'm looking for a word that exactly describes the following idea: basically, there's an obvious and simple relationship between how large something is, how far away from it you are, and how large it appears to you. I want the term for how large it appears. Another way to think of this would be how much of your visual real estate it's taking up.

The closest term I could think of was "apparent magnitude" from astronomy, which measures how bright stars look, regardless of what their actual size or brightness is. I would like the same idea but for area. For instance, a mug held 3 inches from your eyes will have a higher (blank) than a car sitting 1000 feet away from you.

Anyone know what this might be called? I'm sure there has to be a term for it. This might be the wrong forum but I don't know what science forum would be right.

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    If anyone is seeking an explanation of the phenomenon referred to, this - youtube.com/watch?v=MMiKyfd6hA0 - is obligatory Nov 5, 2021 at 6:32
  • Parallax appears to be the word you're after.
    – user405662
    Nov 5, 2021 at 15:44
  • @HighPerformanceMark I have never even heard of this show, but AMAZING
    – HFBrowning
    Nov 5, 2021 at 16:12

2 Answers 2

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visual angle

Visual angle is the angle a viewed object subtends at the eye, usually stated in degrees of arc. It also is called the object's angular size.
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If one looks at a one-centimeter object at a distance of one meter and a two-centimeter object at a distance of two meters, both subtend the same visual angle of about 0.01 rad or 0.57°. Thus they have the same retinal image size. Wiki

The angle formed by two rays of light or two straight lines drawn from the extreme points of a viewed object to the nodal point of the eye. M-W

Obviously you can apply visual angle to any area/measurement, e.g., height, width, diameter etc.

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  • Yes, this is exactly what I was looking for. Thank you! It has the added bonus of being completely unambiguous which is what I need.
    – HFBrowning
    Nov 5, 2021 at 16:07
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Perhaps ‘field of view’, but I don’t know if it would be higher. If anything, it would be lower and not higher for a mug held close to your face. https://en.m.wikipedia.org/wiki/Field_of_view

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