What happens with your eyes when you stare at a star so long it disappears?

When you stare at a star for an extended period, your eyes can experience a phenomenon called "persistence of vision," where the afterimage of the star lingers in your visual field after you shift your gaze. Additionally, your eyes may adapt to the dim light, causing the star to fade from view as your pupils constrict or as your retina becomes less responsive to the light. This can create the illusion that the star has disappeared, even though it is still present in the sky.