How can we see light extremely far away when the source only illuminates...

Light spreads out like a wave. 



Think, of ripples in a pond how they spread out and get more diffuse the farther away from the source. Think of a balloon and how it's opaque before it's inflated, but when you blow it up, it spreads out and you can see through it because it is stretched and less dense, similar principle with light. 

Unlike a balloon which will pop, light, will expand forever, until it is absorbed or reflected by an object.



Here's my video explanation.





The Original Question on Quora.

https://www.quora.com/unanswered/How-come-we-can-see-a-source-of-light-extremely-far-away-when-the-source-only-illuminates-the-area-much-closer-to-it?

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