re: Is there an end or edge to intergalactic space?

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Here's a question for anyone who knows: Why is the observable universe limited to that circle? Is it because the universe may be a sphere so we can only see to the horizon? Or maybe something to do with the amount of time it takes light to get here? Or something else altogether?

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The observable universe is a spherical region of the Universe comprising all matter that can be observed from Earth at the present time, because electromagnetic radiation from these objects have had time to reach Earth since the beginning of the cosmological expansion. There are at least 2 trillion galaxies in the observable universe,[7][8] containing more stars than all the grains of sand on planet Earth.[9][10][11] Assuming the Universe is isotropic, the distance to the edge of the observable universe is roughly the same in every direction. That is, the observable universe is a spherical volume (a ball) centered on the observer. Every location in the Universe has its own observable universe, which may or may not overlap with the one centered on Earth.

The word observable used in this sense does not refer to the capability of modern technology to detect light or other information from an object, or whether there is anything to be detected. It refers to the physical limit created by the speed of light itself. Because no signals can travel faster than light, any object further away from us than light could travel in the age of the universe simply cannot be detected, as they have not reached us yet.

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