Molecular astronomy.

The radio observation of molecules in interstellar space of the Galaxy is reviewed. Attention is given to the discovery of new molecules (C2H, HN-13C, etc.), the structure of dense molecular clouds, new molecular clouds, rich in diatomic and triatomic molecules, associated with H II regions and IR sources, SiO interstellar masers, and molecules observed in external galaxies. Recent developments to initiate millimeter-wave observations of molecules from different sites in Australia are discussed.