He returned to Europe in 1937 when he was appointed professor of astronomy at the Charles University of Prague. However, he was forced out again by Hitler's policies in 1939 and escaped to Holland.
Siya bumalik sa Europa sa 1937 kapag siya ay hihirangin ng astronomy, propesor sa University Charles ng Prague. Gayunman, siya ay sapilitang muli sa pamamagitan ng Database ng mga patakaran sa 1939 at escaped sa Holland.