Which branch of astronomy is concerned with the physics of the universe ?
* Stellar astronomy – natural science that deals with the study of celestial objects ( such as stars , planets , comets , nebulae , star clusters and galaxies ) and phenomena that originate outside the atmosphere of Earth ( such as cosmic background radiation ) * Atmospheric physics – study of the application of physics to the atmosphere Atomic , molecular , and optical physics – study of how matter and light interact Biophysics – study of physical processes relating to biology * Medical physics – application of physics concepts , theories and methods to medicine .