Astrophysics

Miss Quill's physics class watched a film on astrophysics which discussed asteroids. Matteusz found the film very boring. (TV: Detained)

The University of Cambridge had an astrophysics laboratory, where Teri Billington underwent her time dilation project. (AUDIO: The Sentinels of the New Dawn)

Bill Potts was tutored by the Twelfth Doctor on physics and astrophysics. (TV: The Pilot)

Rodan also found astrophysics boring. (TV: The Invasion of Time)

Vislor Turlough was an astrophysicist. (PROSE: Turlough and the Earthlink Dilemma)

Doctor Errol Courtney was frustrated when Tia Kofi confirmed that she didn't have any knowledge of astrophysics or quantum mechanics, but tried not to show it. (WC: Tia Kofi Enters the Time Fracture!)

The Ninth Doctor once claimed that Rose Tyler was a genius astrophysicist so that she could be brought to assist his research on Justice Prime. (PROSE: The Monsters Inside)

Behind the scenes
Astrophysics is the science dealing with the nature and behavior of celestial bodies such as black holes and stars, as opposed to astronomy, which deals with their position.