Konstantin Euardovich Tsiolkovsky (Russian: Константи́н Эдуа́рдович Циолко́вский; Polish: Konstanty Ciołkowski) (September 17 [O.S. September 5] 1857 – September 19, 1935) was an Imperial Russian and Soviet rocket scientist and pioneer of astronautic theory who spent most of his life in a log house on the outskirts of Kaluga, about 200 km (125 miles) southwest of Moscow.