While a student he was encouraged by the Dutch astronomer Peter van de Kamp to study nearby stars, which he did for the rest of his life.
His astronomical research was interrupted during World War II when he was conscripted into the German Wehrmacht in 1942 and sent to the Eastern Front.
He finally resumed his research at the Institute, which had been moved by the U.S. Army to Heidelberg after the war.
The Gliese catalog stars are frequent targets of study due to their proximity to Earth, as suggested by their high proper motion.
Gliese published two supplements to this catalog in 1979[4] and 1991[5] in collaboration with Hartmut Jahreiß.