The Opacity of Spiral Disks

The opacity of spiral disk galaxies is an issue that has only recently resurfaced after many years of hibernation. It was not thought to be an important issue in relation to our understanding of galaxies. The theme of The Opacity of Spiral Disks is the determination of just how much of a galaxy's stellar output is reprocessed through the interstellar medium. Many techniques are described and observations over a wide range of wavelengths are discussed. If some of the issues highlighted in the text are true, then we actually know very little about the total optical luminosity of galaxies and the way the luminosity is distributed over the galactic disk. Audience: Informed students and all professional astronomers interested in galaxies.