The molecular universe

Molecular absorption and emission bands dominate the visible, infrared, and submillimeter spectra of most objects with associated gas. These observations reveal a surprisingly rich array of molecular species and attest to a complex chemistry taking place in the harsh environment of the interstellar medium of galaxies. Molecules are truly everywhere and an important component of interstellar gas. This review surveys molecular observations in the various spectral windows and summarizes the chemical and physical processes involved in the formation and evolution of interstellar molecules. The rich organic inventory of space reflects the multitude of chemical processes involved that, on the one hand, build up…