This is me teaching quantum mechanics to astronomers. I care about quantum chemistry because it can be used to simulate the spectrum of atoms and molecules. To detect molecules remotely we need to know what their spectra look like, and we currently don't. Solving this problem is the focus of my current main project, ATMOS - Approximate Theoretical MOlecular Spectra. I use ATMOS to simulate thousands of molecules using a clever combination of organic chemistry and quantum physics.