Seeing things at night. Why can some things be seen out of the corner of your eye?

[Shady At Best]

I started a thread asking about how high visually one can one see a laser in the night sky and it made me think of something else. I was shining my laser straight up and my buddy who lives about 4 miles away could barely see it but only if he was not trying to focus on it. He had to look to the left or right and it would be visible.
That made me start thinking about trying to spot objects that are barely visible to the naked eye at night like some satellites, stars, nebula's, and clusters. I always noticed that these things are easier to see if I am not focused on them. Like a moving satellite being caught out of the corner of our eye. The phenomenon was brought up in a chapter in an astronomy class I took years ago but i didn't pay much attention to it. Anyone else know what I am talking about or experience it?

 

[Cyparagon]

In low light, you use more "rod" cells than "cone" cells. Your center of vision - the fovea - is populated mainly with cone cells, while your peripheral vision consists of a higher concentration of rod cells.

Fovea centralis - Wikipedia, the free encyclopedia

 

[Shady At Best]

well there it is

 

[Jakedjoe]

In low light, you use more "rod" cells than "cone" cells. Your center of vision - the fovea - is populated mainly with cone cells, while your peripheral vision consists of a higher concentration of rod cells.

Fovea centralis - Wikipedia, the free encyclopedia

The reason for this was way back when humans lived in the wild and had to have a keen eye for predators so we developed good peripheral vision

 

[chipdouglas]

I think your question would be more about peripheral vision. I just saw a thing on discovery channel about it. Its a trait that animals have developed for survival. Low quality imagery but very sensitive to any movements

Michael.

 

[Teej]

The first answer is closest.

The central ~ 2° of your vision, your fovea, is your best color vision, best resolution, best motion tracking part of your vision.

Its also the worst night/low light part of your vision, as the cones that gave you all those bests, suck in low light.

The rods that allow your best low light performance are primarily outside of your fovea.

This is why we DO need to look to the side of what we need to see in low light.

Its a common topic tought to those who need to operate in low light scenarios.