50 Years of Herbig-Haro Research. From discovery to HST

We review the events leading to the discovery of Herbig-Haro objects half a century ago, and the early efforts to understand the nature of these enigmatic objects. The recognition in the mid-seventies of the shocked nature of HH objects heralded a burst of observational and theoretical efforts, and further impetus was soon after provided by the discovery of high proper motions, and by detailed optical, infrared and ultraviolet spectroscopic studies. The recognition in the early eighties of HH jets was the starting point for the increasingly intense studies during the last 15 years which we discuss in this Symposium. In the second half of our review, we summarize the insights into the nature of HH jets provided by analyzing high resolution images obtained with the Hubble Space Telescope of two of the finest known HH jets, HH 47 and HH 111.