With the goal of understanding the physical processes that govern the universe, its constituents, and their origins and evolution, astronomy uses the apparatus and methodology of physics to gather and interpret data. Theoretical work and technology development round out astrophysics.

The undergraduate astrophysics option is designed to give the student an understanding of the basic facts and concepts of astronomy today, to stimulate his or her interest in research, and to provide a basis for graduate work in astronomy/astrophysics.

The primary aim of the graduate astrophysics program is to prepare students for creative and productive careers in astrophysical research. The program consists of core class work in a broad range of astrophysics subject areas then emphasizes independent research. Students are free to pursue study in virtually any area of astrophysics. The opportunity exists to take advantage of the many observational facilities owned and operated by Caltech.

Both undergraduate and graduate students make use of the Cahill Rooftop Observatory.