Dr Johan Stén
University of Jyväskylä, Finland; author
of A Comet of the Enlightenment, a biography of Anders Johan Lexell.
Anders Johan Lexell was the first Finnish mathematical scientist of international renown. He made his name at the St. Petersburg Academy of Sciences in Russia as a close colleague of the great Swiss scientist Leonhard Euler.
In this lecture the speaker will present his life and work and focus on his contribution to the discovery of Uranus. Lexell was on his European Grand Tour passing through London and Oxford in 1781 when the discovery of a new celestial object was announced. Lexell started immediately to calculate its elements and found that the observations fitted a circular orbit better than a parabolic one. It took more than a year of new evidence to convince him that the or-bit was really planetary. The development of his thought will be illustrated with citations from his correspondence.