Introduction

The nature of the nebulae was one of the most pressing questions for astronomers throughout the nineteenth century. It was also a central concern for others, including many popularizers of science, one of whom was the anonymous author of the Vestiges of the Natural History of Creation (1844). By 1864, matters had reached such a pass that Edward Sabine, the President of the Royal Society, reckoned that nebular astronomy had reached a ‘crisis’. The resolution of this crisis was widely seen as a great, if not the greatest, achievement of William Huggins.

Writing for the Nineteenth Century in 1897, Huggins revisited his original observations of nebulae three decades earlier. Huggins invited readers to join him in his observatory at Tulse Hill near London on 29 August 1864 (see Figure 6.1 for a depiction of Huggins in his observatory).

On that night, Huggins recalled, he had turned his telescope and attached spectroscope to the heavens to investigate the light of a nebula, the first time he had done so: