Emma Phoebe Waterman was born at Fort Totten in the Dakota Territory (now North Dakota) in 1882. Her father, John Charles Waterman, commissioned in the U.S. Cavalry, had been sent to Fort Totten after General Custer's failure at Little Big Horn. As a teenager, her parents wanted Phoebe to receive a better education, so they sent her to live with her father's family in Michigan so she could attend high school. She continued her education at Vassar, earning a BA (1904) and MA (1906) in mathematics and astronomy. After graduation, she traveled to the Philippines with her father. Upon her return, she was employed as a computer at the Mount Wilson Observatory in Pasadena, California. Working with several highly respected astronomers ignited her passion to follow her dreams of being one as well. In 1911, she applied and was accepted into the doctoral program at University of California - Berkley. She was awarded a Ph.D. in astronomy in 1913, becoming one of the first of two women to do so.
Shortly after being awarded her Ph.D., Phoebe was appointed as an assistant to the Argentine National Observatory in Cordoba, Argentina. While on the ship to Buenos Aires, she met Otto Haas; they married in February 1914. Phoebe put her astronomy dreams on hold while she supported her husband's business and took care of their family. Despite her commitment to her family, Phoebe never lost her passion for astronomy. Through the suggestions of others, she volunteered with the American Association of Variable Star Observers (AAVSO). In 1927, through the assistance of Leon Campbell, recorder for AAVSO at Harvard Observatory, Phoebe purchased a Clark telescope from the Cranis estate. She used this telescope to make 338 observations between 1928 and 1933.