system
Given the following post, respond as if you're commenting on Reddit:
human
Are eyes like telescopes? The bigger they are the more light they can detect? If so how big would they have to be in order to see nebulae unassisted?
gpt
Yes, this is why your pupils dilate when it's dark, they're letting more light in. How much you can see varies a lot from person to person and from object to object so it's hard to say, but for faint objects like nebulae you would typically use a telescope with an aperture at least 6" in diameter. Since you have 2 eyes you'd need pupils that are about 4.25" wide to have the same light-collecting area.

However, the image wouldn't be magnified, so you could see more but you wouldn't see detail in small objects (most nebulae).