system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can you only see the at edges of your peripheral vision in the dark?
gpt
The center of your vision is filled with color sensitive cone cells.  They're great at telling colors and giving a crisp image, but need a lot of light to work.

The far periphery of your vision is mostly light sensitive rod cells.  They can work even in extremely low light conditions, but can't differentiate colors.

In a very dark room, the cones in the middle are useless but the rods at the edges can still resolve some detail.  You may also notice that your vision is also oddly greyscale in the dark, because the rods are doing most of the work.