Astronomy comes from the Greek Astron, which means "star," and nomia, which comes from the Greek nomos, which means "law" or "culture." Together, they imply "law of the stars" or "culture of the stars." Astronomy should not be confused with astrology, the belief system that asserts human events are associated with celestial object locations. Despite their shared origins, the two fields are today completely separate.
What do we mean when we say "astronomy" and "astrophysics"?
The terms "astronomy" and "astrophysics" are similar. According to the dictionary, "astronomy" is "the study of objects and matter outside the Earth's atmosphere, as well as their physical and chemical properties," whereas "astrophysics" is the branch of astronomy that deals with "the behavior, physical properties, and dynamic processes of celestial objects and phenomena."
In certain contexts, such as the preface of Frank Shu's introductory textbook The Physical Universe, "astronomy" is used to represent the qualitative study of the topic, whilst "astrophysics" is used to describe the physics-oriented version of the subject. However, because much current astronomical study is concerned with physics-related topics, modern astronomy might be referred to as astrophysics. Some areas, like astrometry, are entirely astronomical rather than astrophysical. Various departments where scientists study this topic may use the terms "astronomy" and "astrophysics," depending on whether the department is historically linked with a physics department, and many professional astronomers hold physics degrees rather than astronomy degrees. The Astronomical Journal, The Astrophysical Journal, and Astronomy & Astrophysics are some of the main scientific journals in this discipline.