system
Given the following post, respond as if you're commenting on Reddit:
human
Why can I see very dim (distant) stars if I look away slightly, but when I look at them directly, I can't see them anymore?
gpt
The cells in your eye responsible for detecting faint light (rods) are not in the center of your retina. That pride of place goes to your cones, which are less sensitive in the dark, but which you use a lot more since they give you color information. As a result, your night vision is best when the light is focused off of the center of your retina where your rods are located. That's why when you see something faint, you can lose it when you look directly at it. They also aren't sensitive to red light, which is why people use red flashlights to avoid ruining their nightvision.

As a side note, dim stars are not necessarily distant, they may just be small and cool. All 3 things affect how bright a star appears. Proxima centauri is the closest star to the Sun but is too faint to be seen by the unaided human eye.