The study of the physical nature of astronomical objects, especially stars. Astrophysics has developed mainly in the 20th century and complements the traditional domains of astronomy such as astrometry , stellar dynamics and kinematics, and celestial mechanics .
Observational astrophysics interprets the electromagnetic radiation emitted by celestial objects.
Theoretical astrophysics is concerned with understanding these observations in terms of mathematical models. These models are constructed from the known laws of physics, and may occasionally result in the discovery of new laws under extreme astrophysical conditions. 1. astrometry A Dictionary of Science, Oxford University Press 2. A Dictionary of Science, Oxford University Press 3. The Macmillan Encyclopedia 2001 4.