The natural science that deals with the study of celestial objects and phenomena originating outside the Earth's atmosphere is called Astronomy.
Astronomy’s main activity is the observation of celestial objects measuring their properties such a mss, diameter, brightness and composition. Observations are usually made by way of some form of telescope. The types of telescopes used include visible light, radio, inferred, ultraviolet, X – ray, and gamma ray telescopes.
The telescope has produced a giant leap in astronomy allowing observations beyond the rage of the unaided eye. Since its introduction developments in telescope technology have opened up many new ways of looking at the Universe. Professional astronomy has often come to be seen as equivalent to astrophysics
The 20th century produced a division of astronomy into two main fields. Observational Astronomy is the acquiring of data from observations and analyzing that data using physics. Theoretical Astronomy is the development of computer models to describe astronomical objects and phenomena.
Today Observational and Theoretical Astronomy complement each other. The theoretical Seeks to explain observations and observations used to test the theoretical. Amateur astronomers have also contributed to many important astronomical discoveries making astronomy one of the few sciences that amateurs can still play an active role.