En 1990 cependant la sonde Ulysses a t lance pour tudier les rgions polaires du Soleil.
He spent a great deal of his remaining years critiquing the work of his colleagues in astrophysics.
En comparaison, le noyau de la Terre, lui, ne remplit que 17 de son volume.
In 1632, he was again condemned for heresy after his book 'Dialogue Concerning the Two Chief World Systems' was published.
He demonstrated that energy could be transported by radiation as well as by convection, and that the centres of stars must be at very high temperatures - in the millions of degrees.
Le cratre Hun Kal est en quelque sorte le Greenwich de Mercure.
Trois ans plus tard, La sonde Mariner 10 apportera une meilleure prcision, mesurant la priode de rotation 58,6460,005 jours.
Elle a survol la plante trois reprises, en mars et septembre 1974 et en mars 1975.
