Molecular oxygen densities determined from a solar Lyman &agr; occultation experiment on Solrad 8 during December 1966 through August 1967 show a large apparent seasonal variation in the earth's atmosphere near 100 km. The seasonal variation appears at all latitudes that are examined by the occultation technique, and it does not appear to be associated with latitudinal gradients. Also, the data do not show substantial differences between sunrise and sunset.