Mary Somerville (December 26, 1780 - November 28, 1872) was a Scottish science writer and polymath, at a time when women's participation in science was discouraged.
She was the daughter of Admiral Sir William George Fairfax, and was born at the manse of Jedburgh, in the Borders, the house of her mother's sister, wife of Dr Thomas Somerville (1741 - 1830), author of My Own Life and Times. In 1804 she married her distant cousin, the Russian Consul in London, Captain Samuel Greig, son of Admiral Samuel Greig. They had two children before Grieg died in 1807, one of whom, Woronzow Greig became a barrister and scientist.
After the death of her husband the inheritance gave her the freedom to pursue intellectual interests. In 1812 she married another cousin, Dr William Somerville (1771 - 1860), inspector of the Army Medical Board, who encouraged and greatly aided her in the study of the physical sciences. They had a further four children. After her marriage she made the acquaintance of the most eminent scientific men of the time, among whom her talents had attracted attention before she had acquired general fame, Laplace paying her the compliment of stating that she was the only person who understood his works. She studied mathematics and astronomy, and became the second woman scientist to receive recognition in the United Kingdom after Caroline Herschel.
Having been requested by Lord Brougham to translate for the Society for the Diffusion of Useful Knowledge the Mécanique Céleste of Laplace, she greatly popularized its form, and its publication in 1831, under the title of The Mechanism of the Heavens, at once made her famous. Her other works are the Connection of the Physical Sciences (1834), Physical Geography (1848), and Molecular and Microscopic Science (1869). In 1835, she and Caroline Herschel became the first women members of the Royal Astronomical Society. In 1838 she and her husband went to Italy, where she spent much of the rest of her life.
Much of the popularity of her writings was due to their clear and crisp style and the underlying enthusiasm for her subject which pervaded them. In 1835 she received a pension of £300 from government. She died at Naples on November 28, 1872, and is buried in the English Cemetery there. In the following year there appeared her autobiographical Personal Recollections, consisting of reminiscences written during her old age, and of great interest both for what they reveal of her own character and life and the glimpses they afford of the literary and scientific society of bygone times.
Somerville College, Oxford, was named after Mary Somerville. The term "scientist" was first coined by William Whewell in an 1834 review of Somerville's On the Connexion of the Sciences. Sommerville House, Burntisland is named after her. She lived in the building for some of her life.
Somerville Island (54°44'N 130°17'W)  off British Columbia near the border with Alaska was named after her by Sir William Edward Parry.