Interesting object

why there’s so much darkness?

That’s the rho Oph nebula. It has a lot of gas and dust, so parts of it probably are dark. But the bigger effect is an error in the processing of these images, where we try to estimate how bright the background is. When there are large areas that are all bright, we over-estimate the background level, and then over-subtract that value, so normal-brightness sky becomes too dark.

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