Herman Zanstra
Herman Zanstra (1894 – 1972) was a Dutch-American astronomer.
He earned a Ph.D. at Caltech and wrote a famous paper, An Application of the Quantum Theory to the Luminosity of Diffuse Nebulae, which provided a quantitative method (the "Zanstra method" for understanding the luminosity of nebulas and comets.
After teaching briefly at the University of Washington he went to London and eventually to Amsterdam University.
He won the gold medal of the Royal Astronomical Society in 1961.