Welcome to the subject guide for Astronomy!
Here is an excellent description for astronomy:
"The study of the universe and the objects in it through scientific investigation. Since much of contemporary astronomy uses the laws and methods of physics, the terms “astronomy” and “astrophysics” are usually used interchangeably. However, modern astronomy also uses techniques from many other scientific disciplines, including chemistry, geology, and biology, for which the terms astrochemistry, planetary science, and astrobiology are increasingly used. Even astrometry, the measurement of the positions and motions of stars and other astronomical objects, has links to astrophysical investigations."
"The goal of astronomical research is to understand celestial objects and the nature and evolution of the universe by using whatever techniques are appropriate. Astronomers' breadth of knowledge of different types of astronomical objects often gives insights into understanding any given object or physical process. Some kinds of investigations, such as planetary science, may be perceived as astronomy by many scientists and by others inside and outside the field, but these same investigations may be perceived as geoscience or otherwise and not as astronomy by the scientists carrying out the research."
Pasachoff, Jay M. “Astronomy.” AccessScience. McGraw-Hill Education, 2014. Web. 26 July 2016.