gravitational confines of our planet could be studied only at a distance: namely, from the effect of attraction exerted by their masses; or from the ciphered message of their light brought to us by nimble-footed photons across the intervening gaps of space. A dramatic emergence of long-range rockets in the last decade bids fair to bring about a profound change in this situation. On September 13, 1959 - a memorable date in the history of human endeavour - a man-made missile of Russian origin crash­ landed on the surface of the Moon in the region of its Mare Imbrium, and thus ended the age-long separation of the Earth and its only natural satellite which lasted not less than 4t billion years.