FTP, name this Dutch astronomer who thus hypothesized the supposed source of most comets, known as his namesake cloud.
With Lyman Spitzer, he proposed that anisotropic photoionization of gas clouds could produce a "rocket effect." One of his students predicted the 21 centimeter hydrogen line, which this man confirmed shortly after the detection by Ewen and Purcell. A paper by Lindblad overthrowing Kapteyn's system inspired a paper in which this man presented two formulae for the local effects of galactic rotation using his namesake constants. The distribution of the inverses of the major axes of certain objects led him to hypothesize the existence of a roughly spherical reservoir of debris located about one light year from the Sun. FTP, name this Dutch astronomer who thus hypothesized the supposed source of most comets, known as his namesake cloud.
With Lyman Spitzer, he proposed that anisotropic photoionization of gas clouds could produce a "rocket effect.
Jan Hendrik {Oort}