Education
He received his undergraduate degree in 1940, but World World War II interrupted his studies and he did not get his Doctor of Philosophy until 1961 (on the surface photometry of extragalactic nebulae).
He received his undergraduate degree in 1940, but World World War II interrupted his studies and he did not get his Doctor of Philosophy until 1961 (on the surface photometry of extragalactic nebulae).
Born in The Hague, he spent his entire career at Leiden University except for a brief period (1954–1956) as research assistant at Yerkes Observatory. They had one son, Karel. In a jointly-credited trio with Tom Gehrels and Ingrid, and occasionally including fellow astronomer Bernhard Schmidt, he was an extremely prolific discoverer of many thousands of asteroids.
Gehrels did a sky survey using the 48-inch Schmidt telescope at Palomar Observatory and shipped the plates to the van Houtens at Leiden Observatory, who analyzed them for new asteroids.
The trio are jointly credited with several thousand discoveries. From the statistical properties uncovered it became clear that asteroids fall into certain "families".
He also studied the radial velocities of close binary stars. He never retired, but remained active and published articles until his death, on asteroids and eclipsing binaries.