1. Abstract Cometary comae are generally depleted in nitrogen

2. Nevertheless, in the context of Cometary comae the population of rotational levels does deviate from local thermodynamical equilibrium (LTE) at some distance from the nucleus (Zakharov et al

3. This chapter summarizes our current knowledge of the volatile composition of Cometary nuclei, based on spectroscopic observations and in situ measurements of parent molecules and noble gases in Cometary comae.