Where are all the nebulae located?
Yes, a simple question that should be obvious but apparently is not to me.
To be more explicit, how far are all these objects? Are they mostly in our galaxy?
I'm not suggesting that the Milky Way galaxy is the only galaxy that has nebulae, but that the ones we have pictures of are only within the Milky Way...if that is indeed the case.
This may also apply to stars themselves. What is the radius in ly of discernibility of (most) stars? Is it beyond the distance to the center of our galaxy (where even in principle individual stars might be discernible but there's too much of a mess to differentiate)?