Adapted from How Big is the Solar System?
Many astronomers look for, or create, equations to match their observations of the universe. Mathematics plays an important role in astronomy. To help "wrap our heads around" the sizes of some local astronomical objects, scale models can prove useful. It is a very big universe, after all...
One such model is the Logarithmic map of the universe put together by members of the Sloan Digital Sky Survey. In this model, every "step" is 10 times further than the previous step (like the Richter scale for the strength of earthquakes, or the decibel scale for the loudness of sound).