Interstellar carbon monoxide (CO) was first detected in 1970 with the 36 foot diameter telescope of the National Radio Astronomy Observatory on Kitt Peak in Southern Arizona. R. W. Wilson, K. B. Jefferts, and A. A. Penzias of Bell Labs reported, "We have found intense 2.6 mm line radiation 2 from nine Galactic sources which we attribute to carbon monoxide." Soon afterward, several other basic molecules were also observed in space. IAU Symposium 170, CO: Twenty Five Years of Millimeter Wave Spectroscopy, was organized to commemorate those discoveries. The Symposium reviewed the...

Interstellar carbon monoxide (CO) was first detected in 1970 by R. W. Wilson, K. B. Jefferts, and A. A. Penzias through observations of its lowest rotational transition at 2.6 mm wavelength. This discovery opened the door to a profound new understanding of several diverse yet related fields, including the phases of the interstellar medium, the initial and final phases of stellar evolution, the chemistry of dense and diffuse interstellar matter and of the solar system, the structure of the Milky Way galaxy, and the content and structure of other galaxies. These are among the most fundamental...