The planet Mars in 1973

Review of several international observation programs of Mars, carried out in 1973 - the last favorable period for Martian observations until the 1980's. The results of the Lowell Observatory International Planetary Patrol Program and of observations by the Association of Lunar and Planetary Observers in France, Japan, Britain and elsewhere are discussed and are shown in diagrams and photographs. Attention is given to the changes in Martian features and to the factors affecting observations adversely.