1. Mary Somerville
2. Caroline Herschel
Caroline Herschel was the first woman to discover a comet — and went on to find eight in total. She also discovered several deep-sky objects, including the Sculptor Galaxy. King George III granted Caroline a £50 salary for her work, making her the first woman to earn a living from astronomy.
3. Mary Anning
Mary Anning was a fossil hunter whose finds made an important contribution to the understanding of the Earth's history during her lifetime. She found the very first ichthyosaur skeleton when she was just 12 years old, and the first two plesiosaur skeletons, among many others.
4. Emmy Noether
5. Henrietta Leavitt
Leavitt gave us the first step on a ladder that we still use to measure cosmic distances today. Working at Harvard College Observatory in 1912, she showed a link between the brightness of a Cepheid variable star and how long it takes to brighten and dim. This property means Cepheid variables are immensely useful for measuring distances in the universe.
6. Alice Catherine Evans
7. Annie Maunder
Annie Maunder was top of her class when she studied mathematics at Cambridge in 1889, but she didn't receive a BA — they were only awarded to men at the time. She went on to study the sun, in particular the solar cycle, with her husband. They documented what is now known as the Maunder minimum, a period of extreme quiet on the sun in the late 17th century.
8. Dorothy Hodgkin
Dorothy Hodgkin developed the technique of protein crystallography and confirmed the structure of penicillin and vitamin B12. She won the Nobel prize in chemistry in 1964 and was the second woman, the first being Florence Nightingale, to receive the Order of Merit.
9. Lise Meitner
10. Jocelyn Bell Burnell
11. Mildred Dresselhaus
Mildred Dresselhaus is often called the "queen of carbon science", and has been studying it in various forms for over 50 years. Graphene is now hailed as a wonder material, and using carbon in electronics is on the horizon. At 82, she's still a professor at MIT and recently won the $1 million Kavli prize in nanoscience.