Henrietta was an American astronomer born in 1868 in Lancaster, Massachusetts. She worked at the Harvard Observatory in Cambridge as a human calculator for astronomer Edward Charles Pickering with the task of measuring and cataloging stars' brightness based on how they appeared on photographic plates. In the early 20th century, women were not allowed to handle telescopes.
Henrietta received an hourly wage of 30 cents, a wage that was half of what a male calculator earned in the early 20th century. In 1912, Henrietta discovered that the brightness of a particular type of twinkling star known as the cepheid was related to how often it pulsed. This meant that for the first time one could measure the distance between stars and galaxies, the size of the Milky Way and the expansion of the universe!
Henrietta died in 1921 and turned 53 years old. After her death, Edwin Hubble used her discoveries to work out his Hubble law, which claimed that the universe was expanding.
The Swedish mathematician Gösta Mittag-Leffler considered - without knowing that she had passed away four years earlier - to nominate her for the 1926 Nobel Prize in Physics. However, Henrietta was never nominated because the Nobel Prize is not awarded posthumously.