[ELI5]Why is it that sometimes things appear more clearly in our peripheral vision than when it is directly looked at?

Question

For example, when looking up the night sky, I can spot more stars in my peripheral vision. But some of them disappear when I look at that very spot directly.

In: 7

Answer 1

I haven’t ready it here, so I might have one point to add:

The punctum caecum or blind spot ( https://en.m.wikipedia.org/wiki/Blind_spot_(vision) )
That’s the location where the optic nerve passes through the retina. Due to it beeing nervous tissue, there are no receptors present.

The wiki has a little test to demonstrate the blind spot.