Question about Light

[Fletcher]

Suppose there was a spherical red light source and that was the only thing that existed. Would your eye see a red ball surrounded by blackness, or would your whole vision be uniformly red, or would you see all red but in decreasing intensity?

[russ_watters]

Have you ever looked at the stars at night...?

[HallsofIvy]

In case you haven't- When you look at the stars at night you see bright lights surrounded by blackness. (Works best far away from city lights- spend a night in the Utah desert some time- it's awesome!)

You would only see "all red but in decreasing intensity" if there were a cloud of something to reflect the light around the source.

[Fletcher]

Maybe my question is more biological but, wouldn't light from a sphere come out in every direction and thus hit every part of your eye, assuming there was absoluely no other source of light?

[russ_watters]

Yes, if your eye didn't have a lens on it to focus the light.

[Fletcher]

I had no notion of a lens (I just looked it up) and didn't understand why everything isn't a blur. Thanks.