Mapping the Universe - Mapping Scientific Frontiers: The Quest for Knowledge Visualization - page 66

Fig. 2.18 Orion the Hunter (Courtesy of http://www.cwrl.utexas.edu/ syverson/ )

Greek mythology provides a “memory palace” for us to remember the overall
layout of stars in groups. The influence of terrestrial cartography on celestial
cartography is evidence, for example, the use of twin hemispheres, polar stereo-
graphic projection, terrestrial and celestial globes. Both terrestrial and celestial maps
represent macroscopic phenomena in the world. Similar organizational metaphors
have been developed for mapping microscopic phenomena. Before we leave the
topic of celestial mapping, let us see how scientists pursuit the big picture of the
universe.

2.3.3 Mapping the Universe

Why do scientists map the Universe? Stephen Landy gave an informative overview
of the history of mapping the universe (Landy 1999 ). Astronomers study galaxies.
Cosmologists study nature on its very largest scales; a galaxy is the basic unit of
matter. There are billions of galaxies in the observable universe. These galaxies
form clusters three million or more light-years across. Figure 2.19 is an illustration
on Scientific American in June 1999, showing the scales in the universe. Modern
cosmology has a fundamental assumption about the distribution of matters in the
universe - the cosmological principle, which says that the universe is overall
homogeneous. On large scales, the distributions of galactic bodies should approach