Galaxies are not arranged in a nice grid formation in the sky, nor are they random. Galaxies form part of very large-scale structures or clusters, and some of these clusters are pretty massive. At least two known superstructures lie in the zone of avoidance, where it's difficult to see as the Milky Way obscures the background galaxies. Professor Renee Kraan-Kortweg of the University of Cape Town talks about the Great Attractor and the Vela Supercluster, solving puzzles about how galaxies are moving in space.