Adriaan van Maanen was a Dutch-American astronomer. Born in Friesland, he studied astronomy at the University of Utrecht, earning his Ph.D. in 1911, and worked briefly at the University of Groningen. In 1911, he came to the United States to work as a volunteer in an unpaid capacity at Yerkes Observatory. Within a year he got a position at the Mount Wilson Observatory, where he remained active until his death in 1946.