Editing Max Wolf (section)

== Dark nebulae ==

One of the many significant contributions Wolf made was in the determination of the nature of ''[[dark nebula]]e''. These areas of the sky, thought since [[William Herschel|William Herschel's]] time to be "holes in the sky", were a puzzle to astronomers of the time. In collaboration with [[E. E. Barnard]], Wolf proved, by careful photographic analysis, that ''dark nebulae'' were huge clouds of fine opaque dust.<ref name=bruce />