Unwinding the discovery of spiral nebulae
2005; Oxford University Press; Volume: 46; Issue: 2 Linguagem: Inglês
10.1111/j.1468-4004.2005.46226.x
ISSN1468-4004
AutoresMark Bailey, Carola Butler, John McFarland,
Tópico(s)Historical Philosophy and Science
ResumoEvidence for spiral structure in distant galaxies was first noticed by William Parsons, the Third Earl of Rosse, in April 1845 within a few months of the first trial of his great six-foot reflector the “Leviathan of Parsonstown” on 11 February 1845. Despite the significance of this discovery there are puzzling inconsistencies in the story, and the discovery date — sometime in April — is curiously vague. Here we review the chronology of observations of the two principal players in the story: Messier 51 and Messier 99. The former was identified by Lord Rosse as having a spiral arrangement in the spring of 1845, and the latter “the following spring”. The Revd Thomas Romney Robinson, the third Director of the Armagh Observatory, was observing with Lord Rosse during February and March 1845, and again in 1848, but he apparently only confirmed Rosse's detection of spirality in both galaxies around 11 March 1848. No-one doubted Lord Rosse's discovery of spirality in M51 (and the following year also in M99), but it was almost three years before the observation was confirmed by another astronomer.
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