One of the advantages of developing a universal classification system for any field of study is the ability to make distinctions between things that may share certain characteristics but are nonetheless different. A standardized system also facilitates the communication of knowledge to others. The 2016 Forbes article, “How Do We Classify Stars in the Universe?” illuminates how this is no less true in the field of astronomy when differentiating among stars.
The article consists of an historic overview of how the stars were able to be classified. It explains that an intuitive basis for distinguishing among stars is their color and brightness. Other information can be discerned from the color of a thing, such as its temperature. However, one challenge that needed to be contended with was that the divisions in color are not always so clearly defined. Luckily, a technique called spectroscopy, in which the light is broken up into individual wavelengths, has enhanced the ability to examine the differences in color. Consequently, Angelo Secchi, the 19th century Italian astronomer has been able to formulate the first sophisticated classification system for stars, divided as follows:
“1. Class I: a class for the blue/white stars that exhibited strong, broad hydrogen lines. 2.Class II: yellow stars with weaker hydrogen features, but with evidence of rich, metallic lines. 3.Class III: red stars with complex spectra, with huge sets of absorption features.”
Only a few decades later, researchers were able to build on the work of Angelo Secchi. Edward Pickering and his all-female team at Harvard created the Draper System, subdividing each of Secchi’s Classes. Class I was subdivided A-D, Class II was subdivided E-L, and Class III was M. The decision to establish subdivisions emerged from the understanding that the extent to which the stars exhibited the features designated by each Class fell on a spectrum.
In 1901, Anne Jump Cannon, one of the original team members, further refined the Draper System. The adjustments she made included simplifying the alphabetized system which ranged from A-M to one which only included the letters A, B, F, G, K, M, and O. She also developed an accompanying numerical system, ranging from 0-9, which corresponded to how blue or how red a star was within each lettered Class. The following image illustrates the culmination of Cannon’s effort.
I think this article is relevant to our class because it gives us a sense of the many different areas of study to which classification systems have been applied to advance knowledge. Thanks to Cannon’s contribution, subsequent astronomers were able to learn more about the nature of the stars and their composition. Astronomy is just one of many examples in which classification systems have been used. Other classification systems include the periodic table, and binomial nomenclature (the system adopted to classify different species.) I did not previously make any connection between the classification systems we use in libraries and these other systems. Of course there are differences among them, both in what is being classified, and how it is being classified. However, I think I now see how the motivation for developing them has been similar, which is the need to describe something precisely. As a result, any functional classification system that I know of has multiple levels of division. This is just as true for Dewey as it is for the Draper System.
-Benjamin Ottenstein, INFO 653-01