Martian South Polar Cap 1973

Abstract

Abstract The regression of the Martian south polar cap for the 1973 apparition is examined with the measurements of the photographs of Mars obtained at the Hida Observatory. The 1973 regression curve is compared to the 1971 and 1977 regression curves and to the mean regression curve extracted from the Lowell data for the period 1907–1956. The 1973 regression appears to be faster than the mean regression. On the other hand, the 1971 and 1977 regressions appear to be slower than the mean regression. The behavior of the south polar cap is different from year to year.