Astrophysics is a branch of physics that combines astronomy and physics. Astronomy has to do with space. Physics has to do with the properties of matter and energy.When you combine the two you get the study of the properties of matter and energy in space.
Astrophysics focuses on space as a whole as well as the celestial objects within it. It’s about studying the Sun, stars, galaxies, planets, the interstellar medium, and the cosmic microwave background.