An Apparent Effect of Galactic Rotation on the Intensity of Cosmic Rays

Doppler effect studies of the globular clusters and the extra galactic nebulae have shown a motion of the earth of about 300 km/sec. toward about declination 47°N and right ascension 20 hr. 40 min., which is due chiefly to the rotation of the galaxy. Calculation shows that because of this motion the intensity of cosmic rays at sea level on an unmagnetized earth should be about 1.2 percent greater on the front side than on the back. Taking into account the earth's magnetic field, it is estimated (assuming the cosmic rays reaching the earth to consist of protons and electrons) that the diurnal variation at latitude 45° due to this motion should be, within a factor of 2, equal to 0.1 percent, with its maximum at 20 hr. 40 min. sidereal time. Data published by Hess and Steinmaurer show a sidereal time variation having just this amplitude and phase. While this agreement gives a strong presumption that the cause of this sidereal time variation is the earth's motion through space, another possible explanation is also considered. Experimental methods for making a definite test are outlined. The implication of a galactic rotation effect would be that the cosmic rays originate beyond our galaxy.