system
Given the following post, respond as if you're commenting on Reddit:
human
If the Earth was a giant eyeball, how far would it be able to see into space? Would it outperform modern telescopes?
gpt
In a sense, the Earth *already is* a giant eyeball. By placing telescopes on opposite sides of the Earth, you can combine the data using interferometry to get the same resolution you'd get with an Earth sized telescope.

However, this is easiest to do at longer wavelengths - like radio waves or even microwaves. It's much harder to do with infrared or visible light, and we can only do that on a small scale - like two telescopes on the same mountain. So an Earth-sized eyeball would have a similar baseline to a worldwide radio telescope interferometer, but at shorter wavelengths than we can currently manage. Also, shorter wavelengths are inherently "less fuzzy", so a world-sized optical telescope (or eyeball) would have higher resolution than a world-sized radio telescope.

But in addition to resolution, a world-sized eyeball/telescope would have incredible *sensitivity*. We can use interferometry to combine multiple telescopes to make a high resolution image, but for *sensitivity* you really can't beat just having a huge collecting area.

The night sky actually has lots of nebulae and galaxies that are big enough that you could make them out with the human eye - but they're too dim to be seen well at night. *Sensitivity* is what makes the difference here: if the human eye was bigger, you could pick up a lot more light, and see lots of galaxies and nebulae in the night sky that aren't normally visible.

Currently, the biggest visible light telescopes being built have a mirror 30m in diameter. If the pupil of the world-eye is even 1% of the diameter of the Earth, that's an aperture of ~130 km, and would collect about more than 10 million times as much light, and have thousands of times better resolution.