Extragalactic astronomy
Extragalactic astronomy is the branch of astronomy concerned with objects outside the Milky Way galaxy. In other words, it is the study of all astronomical objects which are not covered by galactic astronomy.
The closest objects in extragalactic astronomy include the galaxies of the Local Group, which are close enough to allow very detailed analyses of their contents. As instrumentation has improved, distant objects can now be examined in more detail and so extragalactic astronomy includes objects at nearly the edge of the observable universe. Research into distant galaxies is incredibly valuable for studying aspects of the universe such as galaxy evolution and Active Galactic Nuclei which give insight into physical phenomena. It is through extragalactic astronomy that astronomers and physicists are able to study the affects of General Relativity such as gravitational lensing and gravitational waves, that are otherwise impossible to study on a galactic scale.Famous Examples of Extragalactic Astronomy
