Examination of the chemistry of the interstellar medium, of protostellar nebulae, and of primitive solar-system objects with a view toward establishing the relationship of the chemical evolution of atoms in the interstellar radiation field to complex molecules and aggregates in the early solar system that may contribute to habitability. Emphasis will be placed on identifying the physical conditions in various objects, timescales for physical and chemical change, chemical processes leading to change, observational constraints, and various models that attempt to describe the chemical state and history of cosmological objects in general and the early solar system in particular. The class is structured as a tutorial, in which small groups of students meet individually with the instructor, and topics are presented by the students. Each student will write papers, give presentations, and lead discussions on 3 topics throughout the term. Course is limited to 12 undergraduate participants, who will be selected at the start of the term based on background, interests, and willingness to commit to the entire term. Fulfills the Institute scientific writing requirement. Given in alternate years; not offered 2026-27.