Hubble revealed a universe of galaxies that existed beyond ours — but he couldn't have done it without a little help.

Henrietta Swan Leavitt. In 1893, a young Leavitt was hired as a "computer" to analyze images from telescope observations at Harvard College Observatory, Massachusetts. Leavitt studied photographic ...

Henrietta Leavitt was born in Cambridge, Massachusetts, the daughter of a Congregational minister. She attended Oberlin College and the Society for Collegiate Instruction of Women (later Radcliffe ...

Measuring a galaxy’s brightness or apparent size is not a good guide to its distance. Hubble leveraged a discovery made by Henrietta Swan Leavitt 10 years earlier. She worked at the Harvard College ...

There are no tape-measures in space, but by the early 20th century Henrietta Swan Leavitt had discovered that the pulsation period of Cepheid variables is directly tied to their luminosity.