Between 1915 and 1930 a major shift had occurred in the way in which the basic astronomical constituents of the universe were conceptualized. In 1915 the fundamental object of interest to cosmologists was the star, and the aim of cosmology was to elucidate the nature of the sidereal universe. In 1935 the galaxy had replaced the star as the primary unit in the interpretation of the large-scale structure of the universe. A focus on the relationship of the Sun within the Milky Way system was replaced by an interest in the place of the Milky Way among the multitude of galaxies that populate space in every direction in the sky. Questions about the universe as a whole now involved the distribution and relative motion of galaxies, their physical structure and probable evolution.

0 0

Post a comment