Smaller the further away

[blackadder10]

Why do objects appear smaller the further away they get?

[lizzysparkle]

Our perception of the size of an object is affected by the size of the image on the retina of the eye.  The more
distant object covers a smaller arc of the visual field and therefore has a smaller image on the retina and we see it as smaller.

[bernardo]

They subtend a smaller angle.

[landie]

So that you can fit objects that are closer to you into your field of vision. If everything remainred the same size you would be scared to set foot outside the door.

[cupra]

Dougal, big cow close - small cow far away ;)