According to Milankovich theory, the large climatic variations of the past are triggered by  the insolation changes on the  surface of the Earth that result from the variations of its orbit and orientation which  are themselves the consequences of the gravitational interactions among the planets. The first long term solution for the motion of the solar system  is due to Lagrange, in the XVIII th  century,  but it was  the further solution of Le Verrier, in 1840  that was used by Croll to build his scenario for the explanation of the ice ages. Since then,  the accuracy of the orbital and rotational solutions for the Earth have largely improved and allowed in 2004, the  astronomical calibration of the Neogene. This calibration was performed  using the correlation of  the sedimentary record with the astronomical solution. Nevertheless, the chaotic motion of the orbits of the solar system (Laskar, 1989) puts a limit to the possibility  of obtaining an accurate solution for the past evolution of the Earth's orbit to about 60 Myr. Going beyond this barrier is still possible using the most stable parts of the orbital solution.