I. O. Yarkovsky and the Discovery of ‘His’ Effect

Ivan Osipovich Yarkovsky (1844-1902, see Figure 1) was a Polish civil engineer working in Russia. By day, he was employed by the Alexandrovsk railway company Moscow-Brest. In his spare time, however, he went deeply into the physical sciences and searched for a "Grand Theory" of the physical world. In 1888 he described a subtle thermal effect that he believed would act on planets and smaller objects orbiting the Sun. This effect fell into oblivion; but about 1950 it was rediscovered and now this so-called Yarkovsky effect is a much-discussed topic in planetary astronomy. Yarkovsky himself, however, has remained completely unknown, as is the way by which he came to his discovery. For millennia people have wondered about the unpredictable behaviour of comets in the sky.As far as we know, the German mathematician and geographer Peter Apian