Elected For.Mem.R.S. 1991
The Netherlands, a small country, has been particularly rich in astronomers in the twentieth century, and Hendrik van de Hulst was among the most notable. He is distinguished for three far–reaching contributions to our knowledge of the Cosmos. As a graduate student he predicted that the hyperfine transition at 1420 MHz in atomic hydrogen (the 21 cm line) would be observable, and later participated in its discovery and early exploitation. He guided Dutch and European space research and its organization from the beginnings. Throughout his entire career he developed the theory of the scattering of radiation by small particles. He was consequently called on to be a member or chairman of important national and international committees, and his contributions, to the advancement of knowledge and effective organization alike, have been recognized by numerous awards and distinctions.