An astrophysicist is a scientist who researches the principles of light, motion, and natural forces as they pertain to the universe at large. He or she engages in theoretical physics studies in an attempt to learn more about the underlying properties of the cosmos. Many astrophysicists specialize in studying a particular phenomenon or theory, such as black holes, the development and extinction of stars, relativity and motion, or the origin of the universe.

Almost every past and present culture has attempted to explain the nature of the cosmos and determine how we came into existence. Astrophysicists incorporate their extensive knowledge of mathematical and physical properties with observable characteristics and to form modern explanations. Scientists frequently dedicate long, tiring hours to conducting trial and error mathematics and reviewing the work performed by their colleagues. So much is unknown or uncertain about the universe that it is not uncommon for an astrophysicist to spend the majority of his or her career investigating a single astronomical circumstance. For example, many scientists have dedicated decades of their professional lives to forming the Big Bang theory, an concept that is now strongly supported yet still not fully understood.

Once an astrophysicist discovers an important trait or forms a valid theoretical explanation, he or she typically presents such information in a formal scientific paper. To become widely accepted, a theory is often subjected to strict peer reviews and tested rigorously by scientific committees. When possible, new theoretical principles or formulas are applied in practical laboratory tests to further support their validity.

To become an astrophysicist, someone must typically receive a PhD in astrophysics or astronomy from an accredited university. After completing educational requirements, he or she may assume a fellowship or internship position at a research institution or university. Post-doctoral research programs, which usually last one to three years, allow new astrophysicists to gain valuable firsthand experience about laboratory and theoretical research techniques by assisting and observing established scientists. Interns and fellows learn how to conduct research, apply for grants, and write scientific papers.

Most astrophysicists conduct independent research at home or in a private research institution. Some experts choose to become professors at colleges and universities, where they teach mathematics, physics, and astronomy courses to the next generation of scientists. An astrophysicist might opt to work in a research and development laboratory at a biotechnology company, putting his or her advanced knowledge of motion and energy to use in practical technology applications.