Introduction : astronomy before Kepler -- Kepler's early life -- Graz (1594-1600), the secret of the universe -- Tycho and Kepler -- Prague (1600-1612), the new astronomy -- Prague, many new things -- 1610, the year of the telescope -- Linz (1612-1626), the harmony of the universe -- The final years (1626-1630), the Rudolphine tables -- Epilogue, the real universe -- Appendix : summary of kepler's travels.