11. The Milky Way as Optical Phenomenon: Perception and Photography in the Drawings of Anton Pannekoek

Abstract

One of Anton Pannekoek's main scientif ic projects was to provide a representation of the appearance of the Milky Way -an object he believed to be an optical illusion. This paper elucidates how Pannekoek thought the Milky Way appearance was formed by a combination of human psychology and physiology, and why he attributed such significance to it. In doing so, it explores the connections between Pannekoek's scientific methodology and his socialist epistemology. The paper also outlines the various techniques Pannekoek employed in his research. To observe the Milky Way, he used both extrafocal photography and visual observations by himself and others. To represent the results, he combined naturalistic drawings with verbal descriptions, numerical tables, and isophotic diagrams.

PANNEKOEK’S GALAXY

“…It is remarkable that the discussions of the 1919 paper at the Amsterdam Symposium (Tai et a.l., 2019) on the distance of the Milky Way do not refer to the sequels Pannekoek (1922bPannekoek ( , 1923a in which he reduced his earlier distance to the Cygnus Cloud by a factor two and subsequently withdrew the result altogether. It is true that the Pannekoek (1922b) paper and the reduction of the distance was noted and discussed in Tai (1920), but I see no reference to Pannekoek (1923a) the spatial structure of the Galaxy as a collection of physical clouds and streams.…”