The controversy in recent years over the status of Pluto as a planet and the less public, but equally important, controversy over whether certain extra solar objects are planets or brown dwarfs, represent only the tip of the iceberg of the more general problem of the discovery, interpretation and classification of astronomical objects. It is a problem long known in science in general and especially in the biological world, where 'natural history,' 'taxonomy,' and 'systematic' form a significant part of the history of biology. But with few exceptions, historians of science have failed to address the subject in a systematic way in the field of astronomy, where it has been more sporadic but no less important.
Intellectual Merit The goal of this research is both to write the narrative history of the astronomical discovery, interpretation and classification of the major classes of astronomical objects, and to address specific core analytical problems. Among them are the following: The nature of discovery as a complex and multifaceted process composed of detection, interpretation, and physical understanding (and possibly others); the role of theory in the discovery of classes of astronomical objects; the role of technology in the detection versus the understanding of these objects; the social aspects of the subject including the role of individuals, world views and scientific communities in negotiating classes and classification systems; comparisons with biology, which has a well-developed historical literature on the subject; and the role of our changing understanding of cosmic evolution in establishing classes of objects.
Potential Broader Impacts Research methods will include the published and archival record as well as oral history interviews. While this research raises central intellectual and historiographic questions, it also bears on real-world problems like the Pluto controversy that astronomers might better address were they informed by this history and its broader interdisciplinary considerations. This research also taps into both the historical and scientific literature to place its subject in the context of similar problems in biology, chemistry and physics. Thus its potential impact is interdisciplinary both within historical disciplines and among the sciences.
On August 24, 2006 the International Astronomical Union (IAU) – the only institution that counts when it comes to official designations of astronomical bodies – declared that Pluto was not a planet. More specifically, astronomers demoted Pluto from a planet to a dwarf planet, and (to the chagrin of many scientists and the confusion of the general public) declared that a dwarf planet was not a planet all, thus reducing the number of classical planets in the solar system to eight for the first time since 1930 when Pluto was discovered. Pluto’s demotion not only meant a rewriting of the textbooks, but also set off a surprisingly intense scientific and public outcry – an interesting cultural phenomenon indicating not only the importance of classification to scientists, but also a deeper investment in astronomy among the general public than one might have thought. This study begins by examining the events leading to the Pluto debate, and the debate itself. It then goes on analyze the problem of discovery and classification in over the last 400 years of telescopic astronomy. It concludes that discovery of new classes of objects in astronomy is an extended process, consisting of detection, interpretation and understanding. But occasionally the detection phase is replaced by inference or declaration, and reclassifications of objects have often occurred with new knowledge. It should come as no surprise, then, that Pluto should be reclassified from planet to a dwarf planet status as knowledge of its true size and mass became known, and as many more bodies of similar mass were discovered in the outer solar system. The declaration by official vote of members of the International Astronomical Union was indeed unusual in the annals of astronomical classification, and the incongruous stipulation that a dwarf planet is not a planet was the result of an imperfect community negotiation. The overall reaction revealed both scientific and cultural biases. But the fact of reclassification is not unusual in the history of astronomy, even if our basic understanding of most classes such as satellites, rings, comets, planetary nebulae and globular clusters, remain stable as their properties are refined. This study also defines a microstructure of discovery, evident when one breaks down detection, interpretation and understanding into their component parts. These parts include technological, conceptual and social roles, including the role of the craftsman, the role of individual psychology, and the role of institutions. Another major finding is strong support for 'collective discovery,' the idea that due to the extended structure of discovery many individuals contribute to any particular discovery, with implications for community consensus, acceptance, and credit. The concept of collective discovery does not help Nobel Prize committees, but it would make them more honest. This is true not only because of the extended nature of discovery over time, but also because of the size of modern research teams. In addition to the analysis of discovery and classification in astronomy, study also produced a comprehensive classification system for astronomy’s 82 classes of objects as defined by the study. The detailed results of the study will be published in book form as Discovery and Classification in Astronomy: Controversy and Consensus (Cambridge University Press, forthcoming, 2013).
