Deflection of Light by the Earth

Abstract

General relativity predicts that light rays are deflected by gravitational fields. This effect has been observed with various degrees of precision on distance scales from 10 exp 11 to 10 exp 23 cm and on mass scales from 10 exp -3 to 10 exp 13 solar masses. The Hipparcos satellite can detect deflection of light by the earth, and can thereby extend the domain of observation by two orders of magnitude in distance and three orders of magnitude in mass. Although the relative deflection induced by the earth is only about 40 micro-as, Hipparcos can detect the effect at about the 8-sigma level.