This is kind of a double question but also related. For example, if you’re laying out looking up at the night sky and stargazing, when you try and stare and focus directly on one star (usually one that’s a little faint), why does it seems to dissappear only to reappear when you move your focus just to the left or right of the star?
Another thing, if you’ve ever laid in your bed at night looking up at the ceiling in a dark room, after awhile you’ll notice your periphery seems to close in and everything gets darker to the point where it feels like you’re closing your eyes until you move yours eyes and it looks normal again. What is happening here? Are these two related/the same thing happening here but just presents itself differently?
In: Biology
There are different types of receptors in our eyes. Cones are responsible for color reception and the focal point on our retina is exclusively packed with cones, which leads to a clearer picture; however, these cones are not the most responsive cell when it comes to picking up light. Rods are more suited to stimulation by light (not color) and can even be stimulated by single photons. Your rods are more dense in the periphery, which is why things like stars can appear brighter when you’re not looking directly at them. I hope this answers your question.
In the dark your fovea (part of the retina that is for clear and colored vision) don’t get enough Light to funtion properly. The retina parts around the fovea don’t need much Light but don’t percieve colors. That is why you see everything as greyish blue in the dark. If you focus on something, the fovea activates and the parts around get sort of blocked by the brain. So you have to move your eyes to have peripheral vision again. I am an optician so I know this. If you have any mire questions don’t hesitate ask me. 🙂
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