Guillermo Haro Barraza (; 21 March 1913 – 26 April 1988) was a Mexican astronomer. Through his own astronomical research and the formation of new institutions, Haro was influential in the development of modern observational astronomy in Mexico. Internationally, he is best known for his contribution to the discovery of Herbig–Haro objects. Early life was born in Mexico City on 21 March 1913 to Ignacio Haro and Leonor Barraza. He studied philosophy and law at the National Autonomous University of Mexico (UNAM). While working as a reporter for Excélsior, Haro became interested in astronomy after a 1937 interview with Luis Enrique Erro. As a result of his dedication and enthusiasm for astronomy, he was hired by Erro in 1943 as an assistant at the newly founded Observatorio Astrofísico de Tonantzintla. Erro arranged for Haro to further his astronomical training in the United States at the Harvard College Observatory, Case Observatory (1944), Yerkes Observatory and McDonald Observatory (1945 to 1947). Career Upon his return to Mexico in 1945, Haro continued working at the Observatorio Astrofísico de Tonantzintla where he was responsible for the commissioning of the new 24-31-inch Schmidt camera and where he became involved in the study of extremely red and extremely blue stars. In 1947 he started working for the Observatorio de Tacubaya of the UNAM. Haro's contributions to observational astronomy, Among them were the detection of a large number of planetary nebulae in the direction of the galactic center and the discovery (also independently done by George Herbig) of the nonstellar condensations in high density clouds near regions of recent star formation (now called Herbig–Haro objects). Haro and co-workers discovered flare stars in the Orion nebula region, and later on in stellar aggregates of different ages. Other major research projects carried out by Haro included the list of 8746 blue stars in the direction of the north galactic pole published jointly with W. J. Luyten in 1961. Work made with the 48-inch Palomar Schmidt using the three-color image technique developed at Tonantzintla. At least 50 of these objects turned out to be quasars (which had not yet been discovered in 1961). Haro's list of 44 blue galaxies, compiled in 1956, was a precursor to the work of Benjamin Markarian and others in searching for such galaxies. Haro also discovered a number of T Tauri stars, one supernova, more than 10 novae, and one comet. Major accomplishments Haro was