Astrophysics is the branch of astronomy that employs the principles of physics and chemistry "to ascertain the nature of the heavenly bodies, rather than their positions or motions in space. A couple of topics that relate to astrophysics are Chemistry,general relativity, cosmology,and galaxy formation and evolution.
Space science is very often associated with physics and astrophysics Physicists have been asking questions about the origins of the universe and using their specialised knowledge to make educated guesses about the past, the present and the future. Mathematics can give information on speed and direction of objects, distances, mass and momentum. .
“Science & Technology in Action.” Space chemistry | Science & Technology in Action, sta.ie/lesson/space-chemistry
Cosmology is the study of the origin, evolution, and eventual fate of the universe. Physical cosmology is the scientific study of the universe's origin, its large-scale structures and dynamics. Cosmology is a branch of astronomy that involves the origin and evolution of the universe, from the Big Bang to today and on into the future. According to NASA, the definition of cosmology is "the scientific study of the large scale properties of the universe as a whole." Cosmologists puzzle over exotic concepts like string theory, dark matter and dark energy and whether there is one universe or many (sometimes called the multiverse). While other aspects astronomy deal with individual objects and phenomena or collections of objects, cosmology spans the entire universe from birth to death, with a wealth of mysteries at every stage.
Reference:“Contributor, Nola Taylor Redd Space.com. “What Is Cosmology? Definition & History.” Space.com, www.space.com/16042-cosmology.html."
In 1905, Albert Einstein determined that the laws of physics are the same for all non-accelerating observers, and that the speed of light in a vacuum was independent of the motion of all observers. This was the theory of special relativity. It introduced a new framework for all of physics and proposed new concepts of space and time. Einstein then spent 10 years trying to include acceleration in the theory and published his theory of general relativity in 1915. In it, he determined that massive objects cause a distortion in space-time, which is felt as gravity.
“Galaxy formation and evolution.” Wikipedia, Wikimedia Foundation, 15 Jan. 2018, en.wikipedia.org/wiki/Galaxy_formation_and_evolution.
The study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning, the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies. Galaxy formation is hypothesized to occur, from structure formation theories, as a result of tiny quantum fluctuations in the aftermath of the Big Bang. The simplest model for this that is in general agreement with observed phenomena is the Λ-Cold Dark Matter cosmology; that is to say that clustering and merging is how galaxies gain in mass, and can also determine their shape and structure.
“Galaxy formation and evolution.” Wikipedia, Wikimedia Foundation, 15 Jan. 2018, en.wikipedia.org/wiki/Galaxy_formation_and_evolution. .