galaxy morphological classification

Tuning-fork-style diagram of the Hubble sequence

Galaxy morphological classification is a system used by astronomers to divide galaxies into groups based on their visual appearance, shape, structure, and distribution of light. There are several schemes in use by which galaxies can be classified according to their morphologies, the most famous being the Hubble sequence, devised by Edwin Hubble and later expanded by Gérard de Vaucouleurs and Allan Sandage. However, galaxy classification and morphology are now largely done using computational methods and physical morphology.