T his was a commission for Scientific American to accompany an article about extragalactic space. Contrary to what you may believe, even the emptiest places are not, well, empty. Extragalactic space is much more tenuous than interstellar space or the space that pervades the Solar System, but it is still not quite a void. Gas surrounds the galaxies and exists between them in a great web-like structure.
Name: Extragalactic Web
Client: Scientific American