[1] He then went to the University of Chicago, where he was published in Astronomy and Astrophysics in 1946 ("Problems of radiative transfer in the theory of stellar atmospheres").
He moved to Caltech in 1951, becoming professor there and working at the Mount Wilson and Palomar observatories.
In 1968, he received the NASA Medal of Exceptional Scientific Merit for his involvement in the Mariner, Viking and Pioneer missions on infrared radiometry.
In 1998 he received the Spanish Civil Order of Alfonso X, the Wise, with the Grand Cross.
His doctoral advisees have included Judith Gamora Cohen, Jim Gunn, Robert A. Parker, Mónica Rodríguez, and Virginia Trimble.