The Muleskinner and the Stars: The Life and Times of Milton La Salle Humason, Astronomer

Ronald L. Voller

“This is the story of the astronomer Milton La Salle Humason, whose career was essential to the development of our understanding of stellar and universal evolution and who helped to build the analytical basis for the work of prominent astronomers and astrophysicists such as Paul Merrill, Walter Adams, Alfred Joy, Frederick Seares, Fritz Zwicky, Walter Baade, and Edwin Hubble. This is the story of the astronomer Milton La Salle Humason.

The improbable journey of Humason began on the banks of the Mississippi River in Winona, Minnesota, in the year 1891 and led him to the foot of Mount Wilson in the San Fernando Valley of Los Angeles County, California twelve years later. It was there in 1903 that he went to a summer camp for the first time and was mesmerized by the natural beauty of the area. After assisting in the construction of the observatory that was to be established by George Ellery Hale on the peak of the mountain, he became one of the organization’s most influential members during the first half of the twentieth century. The mountain would frame his life and career over the next six decades.

The story follows Humason through his extraordinary career in spectroscopy, working alongside Edwin Hubble as the two helped to reconstruct our concept of the universe. The story begins with Humason’s first trip to Mount Wilson and continues on through his days as a muleskinner, leading teams of mules hauling supplies to the summit during the construction of the observatory. The story concludes with Humason’s final days on Mount Wilson. Although Humason did not have any formal education beyond the eighth grade, he was later given an honorary doctorate for his work because he was a patient, knowledgeable, and persistent observer. His mastery of the instrument has become legendary. Throughout his career, he was able to photograph the spectra of stars, galaxies, and other objects that are many thousands of times fainter than what can be seen with the naked eye. As a result of his work, the boundary of the known universe was pushed further into space than it had ever been before. His contributions, which included assisting in formulating Hubble’s Law of redshifts, helped set the field of cosmology firmly on its foundation. His work also included contributions such as these.

During the first fifty years of the 20th century, Milton Humason was widely regarded as one of the most charismatic figures in the scientific community. He was uneducated, street-wise, moonshine ring, roguish, humble, and thoroughly down to earth. He rose to become his day’s leading deep space observer by sheer chance, innate ability, and incredible willpower. The extraordinary life lived by Humason, who Harlow Shapley once referred to as “The Renaissance man of Mount Wilson,” serves as a reminder that passion and purpose can appear in our lives at any given time.”