Visual Observations of Mars, 1956.

Visual observations of Mars are recorded, made with the 82-inch telescope during one month of nearly continuous observation, centered on the time of closest approach in 1956 (September 7) Emphasis was placed on obtaining dependable determinations of the colors of the Martian dark areas and on the general appearance of the planet, including fine detail. The colors, expected to be green at this season (Martian spring), were found neutral gray, with a mere touch of moss-green in some of the equatorial regions and a touch of brown in the dark border surrounding the South Polar Cap. A spectacular system of dust storms was observed to develop, eventually enveloping the entire observable planet except the polar xones. Between September 6 and 9 a dense cloud cap formed over the South Pole, which had cleared away on September 14 and had deposited a new polar cap that has remained largely intact since It is remarkable that this event occurred shortly before the summer solstice The bearing of the surface studies on the vegetation hypothesis is discussed