Later, there will be a verbal description of the changes in thesediagrams. For now, you can do a visual comparison to see how the diagrams have changed.
The "color symbolism"of ISM is discussed on the SCIENCE-page.
Before the first computer-colorizeded diagram, in October 1995,were hand-colored drafts and a black-and-white version (shown below) that simulated colorizationwith shading.
