The shadowing of high-energy cosmic rays by the Moon has been observed with a significance of 9.4 standard deviations with the L3+C muon spectrometer at CERN .
A significant effect of the Earth magnetic field is observed .
Since no event deficit on the east side of the Moon has been observed , an upper limit at 90 % confidence level on the antiproton to proton ratio of 0.11 is obtained for primary energies around 1 TeV .