Katherine Johnson (August 26, 1918- Present)

Mathematician and computer scientist Katherine Johnson was born on August 26, 1918 in White Sulphur Springs, West Virginia to Joylette and Joshua Coleman. Her mother was a teacher and her father was a farmer and janitor. From a young age, Johnson enjoyed mathematics and could easily solve mathematical equations. Her father moved Johnson’s family to Institute, West Virginia, which was 125 miles away from the family home so that Johnson and her siblings could attend school. She attended West Virginia State High School and graduated from high school at age fourteen. Johnson received her B.S. degree in French and mathematics in 1932 from West Virginia State University (formerly West Virginia State College). At that time, Dr. W.W. Schiefflin Claytor, the third African American to earn a Ph.D. degree in mathematics, created a special course in analytic geometry specifically for Johnson. In 1940, she attended West Virginia University to obtain a graduate degree. Johnson was one of the first African Americans to enroll in the mathematics program. However, family issues kept her from completing the required courses.

After college, Johnson began teaching in elementary and high schools in Virginia and West Virginia. In 1953, she joined Langley Research Center (LaRC) as a research mathematician for the National Advisory Committee for Aeronautics (NACA). Johnson was assigned to the all-male flight research division. Her knowledge made her invaluable to her superiors and her assertiveness won her a spot in previously all-male meetings. NACA became the National Aeronautics and Space Administration (NASA) in 1958. Upon leaving The Flight Mechanics Branch, Johnson went on to join the Spacecraft Controls Branch where she calculated the flight trajectory for Alan Shepard, the first American to go into space in 1959. Johnson also verified the mathematics behind John Glenn’s orbit around the Earth in 1962 and calculated the flight trajectory for Apollo 11’s flight to the moon in 1969. She retired from NASA in 1986.

Johnson has been the recipient of NASA’s Lunar Spacecraft and Operation’s Group Achievement Award and NASA’s Apollo Group Achievement Award. She received the NASA Langely Research Center Special Achievement Award in 1971, 1980, 1984, 1985 and 1986. Johnson has co-authored twenty-six scientific papers and has a historically unique listing as a female co-author in a peer-reviewed NASA report. She also received an Honorary Doctor of Laws from the State University of New York in Farmingdale in 1998 and in 1999, was named Outstanding Alumnus of the Year by West Virginia State College. In 2006, Johnson was awarded an honorary Doctor of Science from Capitol College of Laurel, Maryland. Johnson lives with her husband Lt. Colonel James A. Johnson in Hampton, Virginia and has three daughters Constance, Joylette and Kathy.

Maria Mitchell (August 1, 1818 – June 28, 1889)

Maria Mitchell is best known for being the first professional female astronomer in the United States. She discovered a new comet in 1847 that became known as "Miss Mitchell's Comet."

“We especially need imagination in science. It is not all mathematics, nor all logic, but it is somewhat beauty and poetry.”

—Maria Mitchell

Maria Mitchell was born on August 1, 1818, in Nantucket, Massachusetts. She studied astronomy on her own time with the support of her father. In 1847, Mitchell discovered a new comet, which became known as "Miss Mitchell's Comet," gaining her recognition in astronomy circles. She went on to become a professor of astronomy at Vassar College in New York, tracking and taking photos of sunspots with her students.

Astronomer and educator Maria Mitchell was born one of nine children to Quaker parents William and Lydia Mitchell on August 1, 1818, in Nantucket, Massachusetts, where was raised and received her early education.

Mitchell's father, recognizing her interest in the heavens at an early age, encouraged her interest in astronomy and taught her how to use a telescope. She worked as the first librarian at the Nantucket Atheneum library from 1836 to 1856, all the while still gazing at the sky at night, studying solar eclipses, the stars, Jupiter and Saturn.

On October 1, 1847, a 28-year-old Mitchell, while scanning the skies with her telescope atop the roof of her father's place of business, the Pacific National Bank on Main Street in Nantucket, discovered what she was sure was a comet. It turned out that she was right, and that what she had spotted was in fact a new comet, previously uncharted by scientists. The celestial object subsequently became known as "Miss Mitchell's Comet," with the formal title of C/1847 T1.

In recognition of her important discovery, Mitchell was presented with a gold medal by Frederick VI, king of Denmark, who had an amateur interest in astronomy himself. Consequently, Mitchell became the first professional female astronomer in the United States.

The breakthrough brought Mitchell respect and recognition among astronomers and other scientists, and in 1848, she became the first woman to be named to the American Academy of Arts and Sciences. The following year, Mitchell made computations for the American Ephemeris and Nautical Almanac. In 1850, she was elected to the American Association for the Advancement of Science.

In 1856, Mitchell left the Atheneum to travel the United States and abroad, and in 1865, she took a job as professor of astronomy at Vassar College in upstate New York, where she quickly became a well-liked and respected educator. Among many projects, Mitchell and her students continuously tracked and photographed sunspots. In 1882, they documented Venus traversing the sun—one of the rarest planetary alignments known to man, occuring only eight times between 1608 and 2012.

Mitchell was elected to the American Philosophical Society in 1869. Four years later, in 1873, she co-founded the Association for the Advancement of Women, serving as the organization's president for the next three years.

According to the National Women's History Museum, Mitchell once stated, "We especially need imagination in science. It is not all mathematics, nor all logic, but it is somewhat beauty and poetry."

In 1861, after her mother died, Mitchell moved to Lynn, Massachusetts, with her father. In ill health, she retired from teaching at Vassar in 1888, and died on June 28, 1889. She is buried with family members at Prospect Hill Cemetery in Nantucket.

In honor of the first female astronomer, the observatory in Nantucket was named the Maria Mitchell Observatory. Additionally, the Maria Mitchell Association, also in Nantucket; a World War II ship, the SS Maria Mitchell; and a crater on the moon ("Mitchell's Crater") were named after her.

Mitchell was posthumously inducted into the National Women's Hall of Fame in 1994.

Rosalind Elsie Franklin (July 25, 1920 – April 16, 1958)

There is probably no other woman scientist with as much controversy surrounding her life and work as Rosalind Franklin. Franklin was responsible for much of the research and discovery work that led to the understanding of the structure of deoxyribonucleic acid, DNA. The story of DNA is a tale of competition and intrigue, told one way in James Watson's book The Double Helix, and quite another in Anne Sayre's study, Rosalind Franklin and DNA. James Watson, Francis Crick, and Maurice Wilkins received a Nobel Prize for the double-helix model of DNA in 1962, four years after Franklin's death at age 37 from ovarian cancer.

Franklin excelled at science and attended one of the few girls' schools in London that taught physics and chemistry. When she was 15, she decided to become a scientist. Her father was decidedly against higher education for women and wanted Rosalind to be a social worker. Ultimately he relented, and in 1938 she enrolled at Newnham College, Cambridge, graduating in 1941. She held a graduate fellowship for a year, but quit in 1942 to work at the British Coal Utilization Research Association, where she made fundamental studies of carbon and graphite microstructures. This work was the basis of her doctorate in physical chemistry, which she earned from Cambridge University in 1945.

After Cambridge, she spent three productive years (1947-1950) in Paris at the Laboratoire Central des Services Chimiques de L'Etat, where she learned X-ray diffraction techniques. In 1951, she returned to England as a research associate in John Randall's laboratory at King's College, London.

It was in Randall's lab that she crossed paths with Maurice Wilkins. She and Wilkins led separate research groups and had separate projects, although both were concerned with DNA. When Randall gave Franklin responsibility for her DNA project, no one had worked on it for months. Wilkins was away at the time, and when he returned he misunderstood her role, behaving as though she were a technical assistant. Both scientists were actually peers. His mistake, acknowledged but never overcome, was not surprising given the climate for women at the university then. Only males were allowed in the university dining rooms, and after hours Franklin's colleagues went to men-only pubs.

But Franklin persisted on the DNA project. J. D. Bernal called her X-ray photographs of DNA, "the most beautiful X-ray photographs of any substance ever taken." Between 1951 and 1953 Rosalind Franklin came very close to solving the DNA structure. She was beaten to publication by Crick and Watson in part because of the friction between Wilkins and herself. At one point, Wilkins showed Watson one of Franklin's crystallographic portraits of DNA. When he saw the picture, the solution became apparent to him, and the results went into an article in Nature almost immediately. Franklin's work did appear as a supporting article in the same issue of the journal.

A debate about the amount of credit due to Franklin continues. What is clear is that she did have a meaningful role in learning the structure of DNA and that she was a scientist of the first rank. Franklin moved to J. D. Bernal's lab at Birkbeck College, where she did very fruitful work on the tobacco mosaic virus. She also began work on the polio virus. In the summer of 1956, Rosalind Franklin became ill with cancer. She died less than two years later.

Marie Skłodowska-Curie (November 7, 1867 – July 4, 1934)

Marie Curie, née Maria Sklodowska, was born in Warsaw on November 7, 1867, the daughter of a secondary-school teacher. She received a general education in local schools and some scientific training from her father. She became involved in a students' revolutionary organization and found it prudent to leave Warsaw, then in the part of Poland dominated by Russia, for Cracow, which at that time was under Austrian rule. In 1891, she went to Paris to continue her studies at the Sorbonne where she obtained Licenciateships in Physics and the Mathematical Sciences. She met Pierre Curie, Professor in the School of Physics, in 1894 and in the following year they were married. She succeeded her husband as Head of the Physics Laboratory at the Sorbonne, gained her Doctor of Science degree in 1903, and following the tragic death of Pierre Curie in 1906, she took his place as Professor of General Physics in the Faculty of Sciences, the first time a woman had held this position. She was also appointed Director of the Curie Laboratory in the Radium Institute of the University of Paris, founded in 1914.

Her early researches, together with her husband, were often performed under difficult conditions, laboratory arrangements were poor and both had to undertake much teaching to earn a livelihood. The discovery of radioactivity by Henri Becquerel in 1896 inspired the Curies in their brilliant researches and analyses which led to the isolation of polonium, named after the country of Marie's birth, and radium. Mme. Curie developed methods for the separation of radium from radioactive residues in sufficient quantities to allow for its characterization and the careful study of its properties, therapeutic properties in particular.

Mme. Curie throughout her life actively promoted the use of radium to alleviate suffering and during World War I, assisted by her daughter, Iréne, she personally devoted herself to this remedial work. She retained her enthusiasm for science throughout her life and did much to establish a radioactivity laboratory in her native city - in 1929 President Hoover of the United States presented her with a gift of $50,000 donated by American friends of science, to purchase radium for use in the laboratory in Warsaw.

Mme. Curie, quiet, dignified and unassuming, was held in high esteem and admiration by scientists throughout the world. She was a member of the Conseil du Physique Solvay from 1911 until her death and since 1922 she had been a member of the Committee of Intellectual Co-operation of the League of Nations. Her work is recorded in numerous papers in scientific journals and she is the author of Recherches sur les Substances Radioactives (Investigations on radioactive substances) (1904), L'Isotopie et les Eléments Isotopes (Isotopy and isotopic elements) and the classic Traité de radioactivité (Treatise on radioactivity) (1910).

The importance of Mme. Curie's work is reflected in the numerous awards bestowed on her. She received many honorary science, medicine and law degrees and honorary memberships of learned societies throughout the world. Together with her husband, she was awarded half of the Nobel Prize for Physics in 1903, for their study into the spontaneous radiation discovered by Becquerel, who was awarded the other half of the Prize. In 1911 she received a second Nobel Prize, this time in Chemistry, in recognition of her work in radioactivity. She also received, jointly with her husband, the Davy Medal of the Royal Society in 1903 and, in 1921, President Harding of the United States, on behalf of the women of America, presented her with one gram of radium in recognition of her service to science.

The Curie's elder daughter, Iréne, married Frédéric Joliot in 1926 and they were joint recipients of the Nobel Prize for Chemistry in 1935. The younger daughter, Eve, married the American diplomat H.R. Labouisse. They have both taken lively interest in social problems, and as Director of the United Nations' Children's Fund he received on its behalf the Nobel Peace Prize in Oslo in 1965. She is the author of a famous biography of her mother, Madame Curie (Gallimard, Paris, 1938), translated into several languages.

Mme. Curie died in Savoy, France, after a short illness, on July 4, 1934.

Williamina Paton Stevens Fleming (May 15, 1857 – May 21, 1911)

Williamina was a scottish astronomer born in 1857 in Dundee, where she also attended public schools. When she was 21 she moved to Boston with her husband, and fell pregnant. However, her husband abandoned her and she had to seek work to support herself and her new son, Edward.

She became a maid in the home of Professor Edward Charles Pickering, who ran the Harvard College Observatory. He famously stated that he was frustrated with his male assistants and that his maid, Williamina, was capable of doing a better job. Thus, she was employed to do clerical work at the observatory. She soon demonstrated her flare for astronomy and devised a system to classify stars according to how much hydrogen they displayed in their spectra. She also contributed to the cataloguing of stars that would be published as the Henry Draper Catalogue, and in nine years she catalogued over 10,000 stars as well as discovering 59 gaseous nebulae, 310 variable stars and 10 novae. She also discovered the Horsehead nebula on a photographic plate taken by William Pickering.

In 1899, Williamina had proved herself to the extent that she became Curator of Astronomical Photographs at Harvard, and was placed in charge of dozens of other women hired to perform star counts and classifications. In 1906 she became the first American women to be given hononary membership to the Royal Astronomical Society of London. She was also awarded the Guadalupe Alemndaro medal by the Astronomical Society of Mexico for her discovery of new stars. She published A Photographic Study of Variable Stars  in 1907 and Spectra and Photographic Magnitudes of Stars in Standard Regions in 1911.

She died of pneumonia at the age of 54. She has the crater Fleming named jointly for her and Alexander Fleming.

Antonia Maury (March 21, 1866–January 8, 1952)

American born Antonia Maury came from a family with a distinguished scientific background. She was a cousin of Matthew Maury, the oceanographer, a niece of Henry Draper, the physician and astronomer after whom the Harvard star catalogue was named, her sister became a paleontologist, while her father, a clergyman, was also a well-known naturalist.

Maury was educated at Vassar and graduated in 1887; two years later she became an assistant to Edward Pickering at Harvard College Observatory, as well as lecturing at various eastern colleges between 1899 and 1908. Her first assignment for Pickering was to determine the orbital period of the spectroscopic binary Zeta Ursae Majoris, also called Mizar, which was first discovered by Pickering in 1887. Maury independently discovered the second binary, Beta Aurigae and determined its orbital period.

Maury also did a lot of work on spectra, and around the same time that Cannon was revising the system of spectral classification of stars, Maury proposed an additional modification. She argued that not just the absence or presence of a particular spectral line was important, but also its appearance.

Within Cannon’s system, Maury noticed that two stars having the same pattern of lines and colour were also displaying differences in line width and sharpness. She therefore introduced three further subdivisions that recognised these features. She marked stars with normal lines ‘a’, those with hazy lines ‘b’, and those that were sharp, ‘c’; intermediate cases were marked ‘ab’ or ‘ac’. This has been described as the first step in using spectroscopic criteria for the luminosities of stars. However, the system was ignored by her Harvard contemporaries as being too cumbersome, and brought her into direct conflict with Pickering, forcing her to temporarily leave the project in 1892.

Even having left the Observatory, Pickering urged her to complete her work or else hand it over to someone else. Maury demanded to be acknowledged as the author of her work, a gesture commonly denied to women scientists. After much conflict, she eventually got her way, and her catalogue of over 600 stars appeared in volume 28 of the Harvard Annals in 1897, and was the first issue to have the name of a woman on the title page.

Although Pickering continued to downplay the importance of Maury's work,  one person, Ejnar Hertzsprung was quick to see the significance of her classification system and in 1905 pointed out that c-type and ac-type stars were brighter than a- or b-type stars. Of all the catalogues published, only Maury's classification provided the distinction that he was looking for. Maury's work was vital in Hertzprung's formulation which came to be known as the Hertzprung-Russel diagram. Her contribution to spectral analysis was finally acknowledged in 1922 when the International Astronomical Union modified its official classification system based on Annie Cannon's system to include the prefix c-to a certain spectral type defined by narrow and sharp lines.

Although Maury did not return to Harvard for over a decade after the publication of her catalogue, she continued to research spectroscopic binary stars. She turned her attention to the complex spectroscopic binary, Beta Lyrae, and publishing her conclusions based on over 300 spectra of the star in a treatise in the Harvard Annals in 1933.

Henrietta Swan Leavitt, (July 4, 1868—December 12, 1921)

Henrietta Leavitt, American astronomer known for her discovery of the relationship between period and luminosity in Cepheid variables, pulsating stars that vary regularly in brightness in periods ranging from a few days to several months.

Leavitt attended Oberlin College for two years (1886–88) and then transferred to the Society for the Collegiate Instruction of Women (later Radcliffe College), from which she graduated in 1892. Following an interest aroused in her senior year, she became a volunteer assistant in the Harvard Observatory in 1895. In 1902 she received a permanent staff appointment. From the outset she was employed in the observatory’s great project, begun by Edward C. Pickering, of determining the brightnesses of all measurable stars. In this work she was associated with the older Williamina Fleming and the more nearly contemporary Annie Jump Cannon. Pickering's staff, being primarilly made up of women, became known as "Pickering's Harem" or "Pickering's Computers".

Leavitt soon advanced from routine work to a position as head of the photographic stellar photometry department. A new phase of the work began in 1907 with Pickering’s ambitious plan to ascertain photographically standardized values for stellar magnitudes. The vastly increased accuracy permitted by photographic techniques, which unlike the subjective eye were not misled by the different colours of the stars, depended upon the establishment of a basic sequence of standard magnitudes for comparison. The problem was given to Leavitt, who began with a sequence of 46 stars in the vicinity of the north celestial pole. Devising new methods of analysis, she determined their magnitudes and then those of a much larger sample in the same region, extending the scale of standard brightnesses down to the 21st magnitude. These standards were published in 1912 and 1917.

She then established secondary standard sequences of from 15 to 22 reference stars in each of 48 selected “Harvard Standard Regions” of the sky, using photographs supplied by observatories around the world. Her North Polar Sequence was adopted for the Astrographic Map of the Sky, an international project undertaken in 1913, and by the time of her death she had completely determined magnitudes for stars in 108 areas of the sky. Her system remained in general use until improved technology made possible photoelectrical measurements of far greater accuracy. One result of her work on stellar magnitudes was her discovery of 4 novas and some 2,400 variable stars, the latter figure comprising more than half of all those known even by 1930. Leavitt continued her work at the Harvard Observatory until her death.

Leavitt’s outstanding achievement was her discovery in 1912 that in a certain class of variable stars, the Cepheid variables, the period of the cycle of fluctuation in brightness is highly regular and is determined by the actual luminosity of the star. The subsequent calibration of the period-luminosity curve allowed American astronomers Edwin Hubble, Harlow Shapley, and others to determine the distances of many Cepheid stars and consequently of the star clusters and galaxies in which they were observed. The most dramatic application was Hubble’s use in 1924 of a Cepheid variable to determine the distance to the great nebula in Andromeda, which was the first distance measurement for a galaxy outside the Milky Way. Although it was later discovered that there are actually two different types of Cepheid variable, the same method can still be applied separately to each type.