|Asteroids discovered: 1|
|62 Erato||September 14 1860|
He co-discovered asteroid 62 Erato with Oskar Lesser, the first co-discovery on record. The asteroid 6771 Foerster is named after him, and so is the Wilhelm Foerster Sternwarte (William Foerster Observatory; IAU code 544).
He participated in the German Society for Ethical Culture (GSEC) (Deutschen Gesellschaft für ethische Kultur) (in which Albert Einstein also participated) and the German Peace Society (Deutsche Friedensgesellschaft), and resisted the rise in nationalism brought about by the outbreak of World War I.
When 93 German intellectuals signed the Aufruf an die Kulturwelt manifesto in support of the war, Foerster was one of only four intellectuals to sign the Aufruf an die Europäer counter-manifesto (the others were Albert Einstein, the philosopher Otto Buek, and its author, the physiologist Georg Friedrich Nicolai).