 Growing up, Sally Ride was not only interested in science, she was also a nationally ranked tennis player. She earned a Ph.D. in physics in 1978 while doing research on the interaction of X-rays with the interstellar medium. Ride was selected to be an astronaut as part of NASA Astronaut Group 8 in 1978, the first class to select women. She was one of 35 selected out of 8,000 applicants.