The Department of Astronomy offers a graduate program aimed at the PhD degree in astrophysics. Entering students need not have majored in astronomy, although some background in astronomy is desirable. A strong background in physics, however, is essential.
Research is a major part of the PhD program, and the department offers opportunities in a wide variety of fields, including theoretical and observational astrophysics; infrared, optical, and radio astronomy; galactic structure and dynamics of stellar systems; high-energy astrophysics and cosmology; and star and planet formation.
The department has established six years as the normative time to degree. Normative time is the elapsed calendar time in years that under normal circumstances will be needed to complete all requirements for the PhD, assuming a student who enters without deficiencies, who is engaged in full-time uninterrupted study, and who is making desirable progress toward the degree.
Source: Berkeley Academic Guide