Maria Mitchell was born on August 1, 1818, on the island of Nantucket, Massachusetts, the third of ten children of William and Lydia Coleman Mitchell. Her parents were Quakers who believed that girls and boys should receive the same education. William Mitchell was a schoolteacher, cooper, and amateur astronomer who rated chronometers for the island’s whaling fleet. From an early age Maria learned mathematics and the use of astronomical instruments at his side. At twelve she helped him time a solar eclipse. By fourteen she was calculating navigation data for outgoing ships. The island’s seafaring culture, in which women often managed households and civic life while men were at sea for years, gave her unusual freedom to pursue serious study.
After attending local schools, including her father’s and the academy of Cyrus Peirce, Mitchell briefly opened her own school for girls. In 1836 she became the first librarian of the Nantucket Atheneum, a post she held for twenty years. Days were spent among books; nights were spent on the roof of the Pacific Bank, where her father worked as cashier and the family lived, sweeping the sky with a small Dollond refracting telescope. On the evening of October 1, 1847, at about half past ten, she noticed a faint, blurry object five degrees above Polaris that did not appear on any chart. She summoned her father to confirm the observation. It was a telescopic comet, later designated C/1847 T1 and popularly called Miss Mitchell’s Comet. She calculated its orbit and submitted her claim. Although others soon saw the same object, her priority was recognized. In 1848 King Christian VIII of Denmark awarded her a gold medal offered for the first discovery of such a comet. She was only the third woman known to have discovered a comet, after Caroline Herschel and Maria Margarethe Kirch.
The discovery made her internationally famous and America’s first professional woman astronomer. In 1848 she became the first woman elected a Fellow of the American Academy of Arts and Sciences. In 1849 she was appointed a computer for the American Ephemeris and Nautical Almanac, calculating the position of Venus; this made her one of the first women employed by the federal government in a scientific capacity. The following year she was elected to the American Association for the Advancement of Science. She left the Atheneum in 1856 and traveled in the United States and Europe, visiting observatories and meeting leading astronomers. She later left the Quaker meeting, though she retained its emphasis on education and moral seriousness. She never married.
In 1865 Matthew Vassar recruited her as professor of astronomy and director of the observatory at the newly founded Vassar College in Poughkeepsie, New York. She was the first faculty member appointed and the first woman professor of astronomy in the United States. The observatory, equipped with a twelve-inch Fitz telescope that ranked among the larger instruments in the country, became both her home and her laboratory. She lived there with her widowed father until his death. Mitchell insisted that students observe for themselves rather than rely solely on books. “Did you learn that from a book or did you observe it yourself?” she would ask. She and her students photographed sunspots daily and concluded they were whirling vertical cavities rather than clouds. They studied the surfaces of Jupiter and Saturn, double stars, nebulae, comets, and solar eclipses. In 1878 she led a party of students to Denver to observe a total eclipse. Under her teaching Vassar for a time enrolled more students in astronomy and mathematics than Harvard.
Mitchell was an outspoken advocate for women’s education and rights. She helped found the Association for the Advancement of Women in 1873 and served as its president in 1875 and 1876. She argued that women were bound by tradition and authority and would not develop until they learned to question received opinion and seek truth through their own investigations. She objected to the idea that girls should spend hours practicing music merely as an accomplishment when the same time devoted to science or language would produce real intellectual growth. When she discovered she was paid less than younger male colleagues at Vassar, she demanded and received a raise. She supported abolition and women’s suffrage and treated her students as serious scholars rather than ornamental young ladies.
She retired from Vassar in 1888 because of failing health and moved to Lynn, Massachusetts, where she continued observations until her death on June 28, 1889, at the age of seventy. She was buried in Prospect Hill Cemetery on Nantucket. Friends later established the Maria Mitchell Association there to preserve her house and promote science education. She was elected to the Hall of Fame for Great Americans and the National Women’s Hall of Fame.
Mitchell’s career demonstrated that rigorous observation, mathematical skill, and persistence could overcome the barriers of her time. She combined the Quaker conviction that education belonged to both sexes with a scientist’s insistence on firsthand evidence. Her comet discovery opened doors that had been closed to women in American science; her two decades at Vassar trained a generation of students who saw that the sky was not reserved for men. She once wrote that science requires imagination as well as mathematics and logic, and that living nearer to nature brings one nearer to other people. That combination of exacting method and broad human sympathy defined her work and her example.