The word astronomy means either the culture of the stars or the laws of the start. It comes from the astron- and -nomia Greek words. Astron means star, while nomia or nomos means law or culture.
Astronomy is one of the natural sciences that study celestial objects, the chemical and physical processes and evolution of all phenomena that arise from outside the Earth’s atmosphere. It studies stars, planets, moons, asteroids, comets, nebulae and galaxies, together with the actions that derive from these: explosions, cosmic microwave background radiation, supernova explosions etc.
Amateurs can play a significant role in the science of astronomy. They observed and discovered different phenomena that have played an important role in astronomical discoveries. From this point of view, astronomy is part of the science minority in which amateurs are given an important and active role.
The field of professional astronomy divided into two branches at the beginning of the 20th century. These are observational and theoretical sections. The observational branch collects data from the observations over astronomical objects, which are later analyzed using methods stated above, such as physical principles. The theoretical side is concerned with the computer development and the analytical models that characterize the astronomical objects and the phenomena that take place in space. These two disciplines complete one another. The theoretical side attempts to explain the results of the observations, while the observational branch confirms the theories generated by the theoreticians.
Astronomy and astrophysics commonly refer to the same subject. Astronomy is the study of the physical and chemical properties of objects and matter outside of the atmosphere of Earth, while astrophysics focus on the physical properties, behavior and processes of phenomena and celestial objects. Many of the contemporary research is based on subjects related to physics, implying that modern astronomy can also be named astrophysics. Nowadays, only a few sub branches of astronomy focus purely on astronomical science, rather than integrating the physics departments.