Why does light from a fireplace in the dark seem to dissipate abruptly? Why does it not dissipate smoothly over a larger area?

Question

Goes for any light source really, just using a fireplace/bonfire as an example. If you were to look at a bonfire from a distance in the dark, the light seems to stop rather suddenly. But the only way you’re seeing it in the first place is from the light hitting your eyes.

In: 3

Answer 1

Illumination from a light source decreases proportionately to the square of distance. If you look at the graph of 1/x^2 , it really looks like a rather abrupt drop.