atlas, in geography, collection of maps or charts. It usually includes data on various features of a country, e.g., its topography, natural resources, climate, and population, as well as its agriculture and main industries. In astronomy, a star atlas is a collection of maps or photographs covering much or all of the celestial sphere and showing the locations of stars and other objects. Although the first known atlas was compiled by the Greek geographer Ptolemy in the 2d cent. A.D., its modern form was introduced in 1570 with the publication of Theatrum orbis terrarum by the Flemish geographer Abraham Ortelius. In 1595 his close friend Gerardus Mercator published Atlas sive cosmographicae. Its frontispiece was a figure of the titan Atlas holding a globe on his shoulders. The name Atlas subsequently came to be applied to volumes of maps and information in this format.