Abstract
Astrochemistry is “the study of the formation, destruction and excitation of molecules in astronomical environments and their influence on the structure, dynamics and evolution of astronomical objects” as stated by Alexander Dalgarno the pioneer of this field. Astrochemistry comprises observations, theory and experiments aimed at interpreting molecular emission patterns in space. It is, by definition, a multidisciplinary field of research where the sources of uncertainties are numerous. In this talk, I will present the scientific procedure in astrochemistry that goes from the calculations and /or the measurement of molecular data to the determination of the physical conditions lying in astrophysical media. For each step, I will detail the possible source of uncertainties and discuss the global impact of these uncertainties in the knowledge of the chemical complexity in space and of the formation of stars and planets. I will illustrate my presentation with recent examples demonstrating that reducing the uncertainties could lead to significant improvement of our knowledge of astrophysical media.