Types and morphology

Types and morphology

Galaxies come in three main types: ellipticals, spirals, and irregulars. A slightly more extensive description of galaxy types based on their appearance is given by the  Since the Hubble sequence is entirely based upon visual morphological type, it may miss certain important characteristics of galaxies such as  rate (in starburst galaxies) and activity in the core (ingalaxies)

The Hubble classification system rates elliptical galaxies on the basis of their ellipticity, ranging from E0, being nearly spherical, up to E7, which is highly elongated. These galaxies have an profile, giving them an elliptical appearance regardless of the viewing angle. Their appearance shows little structure and they typically have relatively little  . Consequently these galaxies also have a low portion of and a reduced rate of new star formation. Instead they are dominated by generally older, more that are orbiting the common center of gravity in random directions. In this sense they have some similarity to the much smaller .