system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can we see certain stars in our peripheral vision, but then when we look directly at them we can no longer see them?
gpt
You have two different cells in your retina of your eye that can sense light.
-cones, that can see color, but only when there is much light
-rods, that cannot see color, but can see better with little light

the cones, which works best during the day, are in the center of you vision.
the rods are everywhere else.

So when you see a star at your peripheral vision( very precise words by the way), you use your rods, which are better during the night.
When you you look directly at a star, the light falls on the cones, which are not very light sensitive, so the star seems to disappear.