Divided into two parts, the first four chapters of Comets and their Origin refer to comets and their formation in general, describing cometary missions, comet remote observations, astrochemistry, artificial comets, and the chirality phenomenon. The second part covers the cometary ROSETTA mission, its launch, journey, scientific objectives, and instrumentations, as well as the landing scenario on a cometary nucleus. Along the way, the author presents general questions concerning the origin of...