As long as I can remember, I wanted to be an astronomer. In fifth grade, I started an astronomy club among my friends, and proceeded to read every astronomy book I could find in our local library. In high school, I happily took both math courses—geometry and algebra. In college, I majored in astronomy, but also took five years each of math and physics. The only way I managed to get through history and German in my freshman year was because I did not need to spend much time studying math and astronomy. I received a BA in Astronomy from Swarthmore College in 1946, and a PhD in Astronomy from the University of Chicago in 1949.

In my thesis on the Ursa Major Cluster (this cluster includes all but the end stars in the Big Dipper), I studied the motions of many stars to determine which ones were most likely to be members. I used membership in the cluster to determine distances and the brightnesses the stars would have if they were at a standard distance. Then I applied this same method to other clusters, to calibrate the brightnesses of stars from the appearance of their spectra. Astronomers use this method to estimate the distance to stars that are too far away to measure their apparent change in direction as the earth orbits the sun.