I think all of you have ever known about Astronomy. There are different definitions of Astronomy. Some define it as a branch of science dedicated to the study of the motions and natures of celestial bodies, like planets, stars, and galaxies. Others say it is the study of objects and matter outside the earth's atmosphere and of their physical and chemical properties. Still others would say it is the study of everything, because it's a study of the universe and everything is part of the universe.