Far from giving way to pure quantitative classification, galaxy morphology today is a vibrant subject with a huge database of material.
The Hubble tuning fork is being seriously modified. The placement of S0s and the interpretation of dwarf early-types has led to the resurrection of parallel sequence classification.
The high quality of digital images has allowed the old classification systems to be modified to recognise the features of current interest in galactic structure.
High-quality IR galaxy classification and morphology is now possible with NIRS0S and the S4G.
Early-type galaxies continue to be the focus of a great deal of research. ATLAS3D has been a major advance in understanding these galaxies.
S4G provides an opportunity to study the properties of extreme late-type galaxies in great detail.
Various large imaging surveys, like SDSS, the Hubble archives, deep surveys like COSMOS, GOODS, HDF, HUDF, etc., continue to richly add to morphological studies an evolutionary component.
The processes of secular evolution lie in the fine details of galaxy morphology. Interpreting those details is the challenge of the coming years.
Acknowledgments
I am deeply grateful to the organisers of this Winter School for giving me the opportunity to participate as a lecturer in one of the most interesting topics of astronomy today. It was an honour and a privilege to speak to the younger astronomers and to be with such a great group of colleagues. I am also grateful to Gerard de Vaucouleurs and Allan Sandage for inspiring my interest in galaxy morphology almost 40 years ago, and for their encouragement and support over the years that I knew them. Finally, I am grateful to the US National Science Foundation and to the National Aeronautics and Space Administration for past financial support of my extragalactic studies.
This chapter uses images from the Sloan Digital Sky Survey (SDSS). Funding for the creation and distribution of the SDSS Archive has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, NASA, NSF, the U.S. Department of Energy, the Japanese Monbukagakusho, and Max Planck Society. This chapter has also made use of THINGS, "The HI Nearby Galaxy Survey" (Walter et al. 2008), and BIMA-SONG, the Berkeley-Illinois-Maryland "Survey of Nearby Galaxies" (Helfer et al. 2003). Other images are from the archives of the Hubble Space Telescope, the Spitzer Space Telescope, and the Galaxy Evolution Explorer (GALEX). Observations with the NASA/ESA Hubble Space Telescope were obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under contract NAS 5-26555. The Spitzer Space Telescope is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407. GALEX is a NASA mission operated by the Jet Propulsion Laboratory. GALEX data is from the Multimission Archive at the Space Telescope Science Institute (MAST). Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and contracts.