Transcript: The birth of radio astronomy and the development of millimeter and submillimeter astronomy has opened up the capability of astronomers to detect molecules in space. Dozens of molecular species are routinely detected in molecular clouds in the interstellar medium. Radio astronomy is necessary because most of the energy transitions in molecules have low energies and therefore produce spectral features in the submillimeter or far infrared regions of the electromagnetic spectrum. These transitions can be changes of energy level, or changes of vibration, or rotational states of the molecules. Most spectral features are found between a hundred microns and a few millimeters in the electromagnetic spectrum. These spectral transitions are energetically very important in the process of star formation because much energy is contained in the spectral lines, and these spectral transitions become a way in which energy is lost from the center of a molecular cloud allowing the cloud to cool and collapse.