Extraterrestrial Life Debate, Antiquity to 1915: A Source Book

7. ASTRONOMERS AND EXTRATERRESTRIALS

ASTRONOMERS AND EXTRATERRESTRIALS The interactions between the science of astronomy and ideas of extraterrestrial life have been numerous and complex. It is certainly true that developments in astronomy have deeply influenced ideas of extraterrestrial life. But it is also true that biological, physical, metaphysical, and theological beliefs have had an impact on our conceptions of life beyond the Earth. It is less widely recognized that changing conceptions regarding extraterrestrial life have influenced astronomy itself. A central thesis of this chapter is the suggestion that in the period from 1750 to about 1800 aspects of the growing conviction that intelligent life is widespread in the universe had important effects on astronomy. In particular, a claim examined in this chapter is that astronomy in this period began to go through a major transformation, which transformation was significantly influenced by convictions concerning extraterrestrials . In 1750, astronomers were above all concerned with the solar system and especially with positional and mathematical astronomy. They saw the chief goals of astronomy as precise observation of the planetary motions and as development of methods for predicting and explaining these motions. The stars within this perspective provided a backdrop for observing and charting the motions of planets and comets, but beyond this the stellar realm was of minor interest. We shall see that in the period after 1750 interest in stars and in the dim nebulous patches scattered S S E E V V E E N N 129 t h e e i g h t e e n t h c e n t u r y 130 throughout the heavens gradually began to increase. Questions were raised about the arrangement and possible motions of the stars and also about their nature. To a first approximation, it is correct to say that between 1750 and 1800 astronomy began to be transformed from being the science of the solar system to being the science of the universe. Who were the pioneers of the development of stellar astronomy, which is now such a central area in astronomy, and what new ideas facilitated the transformation ? The consensus among experts is that the eighteenth-century pioneers of stellar astronomy were Thomas Wright, Immanuel Kant, Johann Lambert, and above all William Herschel. It is to these authors that credit is accorded for the idea that the appearance known as the Milky Way is due to the stars in our region forming a giant, disk-shaped structure. Similarly these authors explored the claim that the nebulous patches seen in the heavens are nothing less than island universes, massive and remote structures comparable to our Milky Way. It is a striking fact, evident from the readings that follow, that these four authors were also deeply concerned about extraterrestrial life. This, it is suggested, is no accident. For example, they adopted the notion strongly associated with ideas of extraterrestrial life that stars, rather than being just points of light scattered on the inside of a giant sphere with the Sun at the center, are themselves suns, possibly surrounded by inhabited planets. This notion greatly increased the significance of the stars, raised questions about their arrangement and possible motions, and inspired efforts to discover their nature. In the case of William Herschel, the pioneer of stellar astronomy whose observational contribution was paramount, it can plausibly be suggested that his efforts to build the largest telescopes that humans had ever constructed were at first motivated not chiefly by a desire to observe the nebulae in which objects his contemporaries took little interest, but rather by a desire to achieve the most sought after telescopic detection of the modern times: the discovery of direct evidence of extraterrestrial intelligent life. Herschel not only believed this was possible, but compelling evidence (included in this chapter) shows that for a period he believed that he had succeeded in this quest. THOMAS WRIGHT (1711–1786) Among many books that played a role in drawing attention to the stellar region, one of the earliest was a volume published in 1750 by Thomas Wright. His An Original Theory or New Hypothesis of the Universe was possibly the first astronomy book to concentrate on the structure of the stellar region. Moreover, no earlier book had extended the claim for extraterrestrial intelligent life so vigorously into the stellar heavens. It is, however, a curious fact that what has given Wright’s volume its celebrity has been the...