Expanding universe. Diagram illustrating spatial expansion in an expanding universe. The analogy of the universe and its galaxies being situated on the surface of an expanding balloon, is commonly used. Galaxies (white dots) are seen within part of the universe. As the universe expands (left to right), the galaxies all recede from each other. This motion is not through space, but is the expansion of space itself. The group of blue dots demonstrates that the relative distances of galaxies remains the same during this universal expansion. On the largest scale, the galaxies are observed to be receding from us in this fashion.