As interplanetary travel by robot vehicles launched from earth becomes more sophisticated, the solar system neighborhood will be constantly rediscovered. This will lead to the maturation of the science of comparative planetology. This discipline, involved in study of the origin, evolution, and nature of planets, promises significant future…

Discusses the efforts which have been accomplished in extragalactic astronomy (the study of bodies and systems beyond the Milky Way) since 1929. Some of the most perplexing problems of extragalactic astronomy such as the missing mass of the galaxies are also discussed. (HM)

Discusses the birth of the universe and its death. Whether the universe is closed or open is also discussed. (HM)

Presented is one of a series of publications of National Aeronautics and Space Administration (NASA) facts about the exploration of Mars. The Viking mission to Mars, consisting of two unmanned NASA spacecraft launched in August and September, 1975, is described. A description of the spacecraft and their paths is given. A diagram identifying the…

Presents a brief review of man's study of the planets from early visual observations to present day investigation by interplanetary spacecraft. (SL)

This document is one of a series of publications of the National Aeronautics and Space Administration (NASA) on facts about the exploration of Jupiter and Saturn. This NASA mission consists of two unmanned Voyager spacecrafts launched in August and September of 1977, and due to arrive at Jupiter in 1979. An account of the scientific equipment…