Fritz Zwicky (1898–1974) Swiss astronomer
Source: Fritz Zwicky, [On the redshift of spectral lines through interstellar space, Proceedings of the National Academy of Sciences of the United States of America, 15, 10, 1929, 773–779, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC522555/] (quote from p. 773)