Earls was born in Portsmouth, Virginia to Ida and James Deberry Earls.[1][2] His mother was a seamstress and his father worked on the railroads.[3] His parents and first grade teacher encouraged him to work hard at school.[4][5] He attended Crestwood High School in Chesapeake, Virginia.[1] He took part in mathematics and science fairs whilst at high school, and was the first in his family to attend college.[3][4] Earls studied physics at Norfolk State University, where he earned a bachelor's degree in 1964.[5][6] He was initiated into Kappa Alpha Psi in 1963.[7] He was encouraged to attend graduate school and applied to the University of Rochester School of Medicine, and completed a master's degree in 1965.[1]
After earning his doctorate Earls returned to NASA, where he worked in Health Physics whilst simultaneously working toward a business degree at Harvard University.[1][10] He was made Chief of the Health, Safety, and Security Division in 1983 and promoted to Director of the Office of Health and Services in 1988. He was made the Director of the Glenn Research Center in 2003, where he was responsible for technology, research and development, and systems development.[1][10][12] This role involved Earls managing a budget of over a billion dollars and a work force of 4,500.[4] He was part of the launch team for Apollo 13 lunar program.[13]
During his career at NASA Earls held many 'firsts', which included being the first African-American man to be appointed section head, office chief, division chief and deputy director.[1] Earls wrote the two first NASA health physics and environmental resource guides.[13] He also taught mathematics, physics and radiation biology at Capital University.[13]
Earls is married to Zenobia, a Cleveland public school teacher, with whom he has two sons. Julian Earls, Jr, who is a neurologist, and Gregory Earls, a filmmaker who lives in Inglewood, California. Dr. Earls has two granddaughters.[1][15] Earls is an athlete who has completed 27 marathons.[19][22] In 2002 he was a torch bearer for the Salt Lake City Olympic Games.[19]