Published online by Cambridge University Press: 04 August 2017
Twenty years after their first discovery at Dwingeloo (Muller, Oort and Raimond 1963), the nature and origin of high-velocity clouds (HVCs) remain enigmatic. Yet, much important progress has been made in the study of their properties, and prospects are brightening that the problem of their distances, which holds the key to their understanding, may soon be solved.