This key idea explores the role of women in advancing the field of astronomy. The author highlights the significant contributions made by women who worked as "human computers" at the Harvard Observatory in the late 19th and early 20th centuries. These women were hired to analyze astronomical data, a job that was considered menial and tedious at the time. However, they proved to be incredibly skilled and dedicated, and their work was crucial to the development of astronomy.

The author notes that women were attracted to astronomy because it was considered a "suitable" profession for women at the time. However, many of these women were highly educated and talented individuals who could have pursued other careers if they had been given the opportunity. Despite facing discrimination and being paid less than their male colleagues, these women persevered and made lasting contributions to the field of astronomy.

One of the most notable women mentioned in this key idea is Williamina Fleming. She was a Scottish immigrant who was hired by the Harvard Observatory in the 1880s to classify stars. She discovered the existence of white dwarf stars, which were previously unknown to astronomers. Her discovery paved the way for future research on these types of stars.

Another important woman in astronomy mentioned in this key idea is Henrietta Swan Leavitt. She discovered the period-luminosity relationship, which is a fundamental concept in modern astronomy. This relationship is used to measure the distance between galaxies and has helped astronomers map the universe.

Annie Jump Cannon is also highlighted in this key idea for her work in developing the stellar classification system. This system is still used today and has helped astronomers better understand the properties of stars.

Cecilia Payne-Gaposchkin's discovery of the composition of stars is also mentioned in this key idea. She was the first person to suggest that stars were composed mostly of hydrogen and helium, which was a radical idea at the time.