# Eli5 why are you able to see lights far away but the light it projects doesn’t go nearly as far? (Car lights, street lights, etc)

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Eli5 why are you able to see lights far away but the light it projects doesn’t go nearly as far? (Car lights, street lights, etc)

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The lights it projects does go so far – that’s how you see the light in the first place. But for something to be illuminated, the light has to make it to the object, reflect, and make it all the way back to your eye. That’s a much more taxing journey on the intensity of the light than simply shining at you.

Let me see if I understand what you’re asking, because the question is awkwardly phrased:

Are you asking why we can see the light shining from far away (like seeing car lights from far away), but can’t see things illuminated by the same light just as well (like when driving)?

Simply put; it doesn’t take much light to be seen, but it takes a lot of light to project and reflect off of other things.

For starters, if I shine a light at you and you are 100 meters away, that’s only 100 meters it has to travel for you to see it.
If it then bounces back from you, so that I can see it (and therefore see you), thats another 100m. That’s 200m now.

The light weakened on its way to you, by bouncing into particles and whatnot, and then kept weakening on its way back to me.

On top of that, not all the light is going to be bouncing back in the first place, unless you happen to be a perfect mirror.

Our eyes see by detecting photons and they are pretty darn good at it. Does not take a ton of photons to see ( detect) light.

Car lights. When you are looking directly at them, your getting ALL the photons hitting your eyes. blinding up close, less far away but at a long distance your sill getting some

If your sitting in the car. The photons are not going straight to your eye. The photons are going out and bouncing back to you. Many are absorbed by material before coming back to your eyes. ( like the light is white, BUT you only see the colours of the stuff you can see. ). This means there are less photons hitting your eyes, Vis a Vis less light.