Extragalactic Astronomy is the branch of astronomy concerned with objects outside of our own Milky Way Galaxy.

As instrumentation has improved, more distant objects can now be examined in detail. It is therefore often useful to sub-divide this branch into Near-Extragalactic Astronomy and Far-Extragalactic Astronomy. The former deals with objects, such as the galaxies of our Local Group, which are close enough to allow very detailed analyses of their contents (e.g. supernova remnants, stellar associations). The latter describes the study of objects sufficiently far away that only the brightest phenomena are observable.

Some topics include:

• Supernovae
• Quasars
• Radio galaxies
• Groups and clusters of galaxies

See also Galaxy formation and evolution

General subfields within astronomy