Dr Dopita is one of the top two or three international authorities in the very active field of interstellar astrophysics. His range of achievements in theoretical astrophysics and ground-based and space observational astrophysics is extraordinarily broad. He has made fundamental contributions to research on astrophysical plasma diagnostics, star formation in galaxies, the physics of planetary nebulae, supernova remnants, active galactic nuclei and radio jets. He is a major user of the Hubble Space Telescope, and his prestige and judgement were recognised by his appointment to the Hubble Space Telescope Time Assignment Committee.