Astronomy’s basic activity is observation of celestial objects so as to measure 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 produced a giant leap in astronomy allowing observations beyond the rage of the unaided eye. Further developments in telescope have opened up whole new ways of looking at the Universe. Professional astronomy has often come to be seen as equivalent to astrophysics
The 20th century saw the 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.