thumb|300px|ESO 162-17 is an example of a peculiar galaxy which is 40 million light-years away in the constellation [[Carina (constellation)|Carina.]]
A peculiar galaxy is a galaxy of unusual size, shape, or composition. Between five and ten percent of known galaxies are categorized as peculiar. Astronomers have identified two types of peculiar galaxies: interacting galaxies and active galactic nuclei (AGN).
When two galaxies come close to each other, their mutual gravitational forces can cause them to acquire highly irregular shapes. The terms 'peculiar galaxy' and 'interacting galaxy' have now become synonymous because the majority of peculiar galaxies attribute their forms to such gravitational forces.
See also
- Atlas of Peculiar Galaxies
- Irregular galaxy
- Starburst galaxy
- Arp 87
- Mayall's Object
- Arp 147