- The definition of astrophysics is a branch of astronomy that studies the composition and origin of objects in outer space along with the way they interact with each other and other matter.
A person who studies black holes, dark matter, and cosmic strings is an example of a person who is involved with astrophysics.
the main branch of astronomy which deals primarily with the physical properties of the universe, including luminosity, density, temperature, and chemical composition
noun(used with a sing. verb)
The branch of applied physics that deals with astronomical phenomena.