Astrometry and Relativity

General relativistic effects in astrophyiscal systems have been detected thanks to accurate astrometric measurements. We outline some keystones of astrometry such as stellar aberration (argument development during the years 1727-1872); Mercury's perihelion precession (1845-1916); solar disk oblateness (1966-2001); relativistic light deflection (1916-1919); lunar geodetic precession (1916-1988); Lense-Thirring and Pugh-Schiff precessions (1917-1959), finally presenting the issue of the quest for a guide star for GP-B satellite (1974-2004) as application of all previous topics.