The science that deals with the origin, evolution, composition, distance, and motion of all bodies and scattered matter in the universe. It includes astrophysics, which discusses the physical properties and structure of all cosmic matter.
Astronomy comprises the study of all extraterrestrial objects.
Until the invention of the telescope and the discovery of the laws of motion and gravity in the 17th century, astronomy was primarily concerned with noting and predicting the positions of the Sun, Moon, and planets, initially for calendrical and astrological purposes and later for navigational applications and scientific interest. The catalog of objects now studied is much broader and includes, in order of increasing distances, the solar system, the stars that make up the Milky Way Galaxy, and other more distant stellar objects and galaxies. With the advent of scientific space probes, the Earth also has come to be studied as one of the planets, though its more detailed investigation remains the domain of the geologic sciences. Astronomy is the most ancient of the sciences, having existed since the dawn of recorded civilization. Much of the earliest knowledge of the celestial bodies is often credited to the Babylonians.