The history of science is, like so much else, a human history. But history tends to get simplified; a map becomes a single road leading from point to point. It's not surprising that some scientists who contributed invaluably to the field have been kept out of the dominant narrative because they were women. But in the last days of the 19th century and the early days of the 20th, Henrietta Swan Leavitt - one of the many woman computers" at the Harvard Observatory - used the measurements of variable stars to determine fixed distances across space. And fifty years later, Katherine Johnson - a black woman working at NASA's Langley Research Center in Virginia when the state was still deeply segregated - would map John Glenn's space flight, and America's trip to the moon. Women are indelible contributors to the field, and two of this year's best histories - Margot Lee Shetterly's Hidden Figures, and Dava Sobel's The Glass Universe - are out to prove it. There's deep value to these stories in the here and now. Women fought prejudice (twice over, in the case of Hidden Figures) and did crucial work that shaped our understanding and exploration of the universe. From a glass-plate storage room in the Observatory, Williamina Fleming could look at a far-off star and map it in a sea of numbers; in a segregated Virginia, Katherine Johnson could look at a sea of numbers and map out a path to the Moon. Taken together, these books make a case not just for acknowledging women's contributions to the field, but for the value of science itself.