Photo courtesy Physics Today
Hendrik Christoffel van de Hulst
19 November 1918	1978 Bruce Medalist	31 July 2000

“Henk” van de Hulst was born and educated in Utrecht, where he completed his war-interrupted doctorate under Marcel Minnaert in 1946. He made his most important discovery during the war: stimulated by a suggestion of Jan Oort, van de Hulst predicted in 1944 that clouds of hydrogen gas in space should emit and absorb a spectral line at wavelength 21 cm. After this radiation was detected in 1951, he, Oort, and C. Alex Muller led the Dutch team which, along with an Australian team, mapped the clouds of the Milky Way and delineated its spiral structure. Van de Hulst made extensive studies of interstellar grains and their interaction with electromagnetic radiation. He wrote important books on light scattering and radio astronomy. He investigated the solar corona and the earth’s atmosphere. After two years at the Yerkes Observatory, he taught and researched at the University of Leiden from 1948 until his retirement in 1984. He was the first president of the international space committee of COSPAR and a leader in several other international organizations and in the development of Dutch and European space research.

Presentation of Bruce medal
Mercury 7, 89 (1978).

Other awards
Astronomische Gesellschaft, Karl Schwarzschild Medal, 1995.
French Academy of Sciences, Janssen Medal, C. R. Acad. Sci., Sér Gen., Vie Sci. 9, 5, 370 (1992).
National Academy of Sciences, Henry Draper Medal, 1955.
National Radio Astronomy Observatory, Jansky Lectureship, 1987.
Royal Astronomical Society, Eddington medal, 1955, presented by John Jackson, MNRAS 115, 202 (1955).
Royal Society and COSPAR, Massey Award, 1990.

Biographical materials
Cook, Alan, Biographical Memoirs of the Royal Society, 47, 465–479 (2001).
van de Hulst, H. C., “Roaming Through Astrophysics,” Ann. Rev. Astron. Astrophys 36, 1 (1998) .

Obituaries
Habing, H.J., Astronomy & Geophysics 42, 1, 1.33-1.35 (Feb 2001).
Hovenier, J.W., Journal of Quantitative Spectroscopy and Radiative Transfer 68, iii-v (2001).
University of Leiden
Welther, Barbara L., Bull. Am. Astr. Soc. 32, 1688-89 (2000).

Portraits
AIP Center for History of Physics
Annual Reviews of Astronomy & Astrophysics 36, 1 (1998).
Eric Weisstein’s World of Biography

Named after him
Minor planet #2413 van de Hulst [#2412 Wil was named after his wife]
A tree was planted in his memory at the headquarters of the European Space Agency.

More references