Kirstine Bjerrum Meyer was a Danish physicist and teacher. She became the first Danish woman to earn a PhD in natural sciences from @uni_copenhagen in 1909, specialising in the physics of temperature. In 1902, Meyer founded Danish Journal of Physics. #STEMlegends #WomenInSTEM pic.twitter.com/6NaG1Z4Fyx

— RAS Women in STEM (@RAS_Women) June 30, 2018

Margaret Eliza Maltby was an American physicist and the first woman to gain a PhD in physics from a German university. She campaigned against the forced resignation of married women, and in 1906, was recognised as one of America's best scientists by American Men of Science. pic.twitter.com/7a25OkYHXi

— RAS Women in STEM (@RAS_Women) June 29, 2018

Married women weren’t allowed at @MIT in 1906: "the College cannot afford to have women on the staff to whom the college work is secondary; the College is not willing to stamp with approval a woman to whom self-elected home duties can be secondary". #STEMlegends #WomenInSTEM

— RAS Women in STEM (@RAS_Women) June 29, 2018

Chika Kuroda was a Japanese chemist. She became the first Japanese woman to receive a Bachelor of Science in 1916 while at @TohokuUniPR. She became a professor at @TohokuUniPR and later Tokyo Women's Higher Normal School. She completed her PhD in 1929. #STEMlegends #WomenInSTEM pic.twitter.com/C81uOaGMHw

— RAS Women in STEM (@RAS_Women) June 28, 2018

Florence Cushman was an American astronomer at the Harvard College Observatory. She worked with Annie Jump Cannon on the Henry Draper catalogue, which was published between 1918 and 1924 and gave spectroscopic classifications for 225,300 stars. #STEMlegends #WomenInSTEM pic.twitter.com/pjfztfDTMN

— RAS Women in STEM (@RAS_Women) June 27, 2018

Roger Arliner Young was an American biologist. She published in @sciencemagazine in 1924, becoming the first black American woman to publish in this field. She became the first black American woman to gain a PhD in zoology in 1933, while at @OhioState. #STEMlegends #WomenInSTEM pic.twitter.com/uB8DGH90T1

— RAS Women in STEM (@RAS_Women) June 26, 2018

Margaret Chorley Crosfield was a British geologist, educator and promoter of women's suffrage. She became member of @GeolAssoc in 1892 and @BritSciAssoc in 1894. She was one of the first six women to be elected Fellows of @geolsoc in 1919. #STEMlegends #WomenInSTEM pic.twitter.com/pnThKl1w5m

— RAS Women in STEM (@RAS_Women) June 25, 2018

Alice Grace Cook was a British astronomer from Suffolk. During WWI, she co-headed the @BritAstro Meteor Section with Fiammetta Wilson, and was sole director from 1921 to 1923. She was one of the first women to become a Fellow of @RoyalAstroSoc in 1916. #STEMlegends #WomenInSTEM pic.twitter.com/EfCQJeCvjm

— RAS Women in STEM (@RAS_Women) June 24, 2018

Marcia Anna Keith was an American physicist and teacher. She researched the physics of heat transmission in gases at low temperatures and helped establish @APSphysics in 1899. She was a pioneer in the field of physics education, particularly for women. #STEMlegends #WomenInSTEM pic.twitter.com/08enC1Okho

— RAS Women in STEM (@RAS_Women) June 23, 2018

Anna Winlock was an American astronomer who specialised in asteroids. She was the first of several women to work as a 'computer' for @Harvard Observatory in the 1880s, under director Edward Charles Pickering. #STEMlegends #WomenInSTEM pic.twitter.com/GHLPxgs3ZA

— RAS Women in STEM (@RAS_Women) June 22, 2018

Some suggest Pickering was progressive for hiring women, although they were only paid half what a man would have been. #STEMlegends #WomenInSTEM

— RAS Women in STEM (@RAS_Women) June 22, 2018

Kono Yasui was a Japanese biologist. She became the first woman published in the journal Zoological Science in 1905 when she began her graduate degree. She became the first Japanese woman to receive a PhD in a science subject in 1927. #STEMlegends #WomenInSTEM pic.twitter.com/f75hJ974eK

— RAS Women in STEM (@RAS_Women) June 21, 2018

Edith Elizabeth Farkas was a Hungarian Antarctic researcher emigrated to New Zealand as a refugee. She was the first women in the New Zealand MetService to set foot in Antarctica in 1975, and monitored the ozone for over 30 years. #STEMlegends #WomenInSTEM #WorldRefugeeDay pic.twitter.com/j1BEdi4TdP

— RAS Women in STEM (@RAS_Women) June 20, 2018

Fiammetta Wilson was a British astronomer. During WWI, she became an acting director of the @BritAstro Meteor Section with Alice Grace Cook. She observed about 10,000 meteors, and accurately calculated the paths of 650. #STEMlegends #WomenInSTEM pic.twitter.com/8PxOztcDM8

— RAS Women in STEM (@RAS_Women) June 19, 2018

Cook wrote of how Wilson worked even when “zeppelins [were] dropping bombs in the neighbourhood” or “falling splinters from shrapnel…made things highly dangerous”. Wilson was one of the first women to become a Fellow of @RoyalAstroSoc in 1916. #STEMlegends #WomenInSTEM

— RAS Women in STEM (@RAS_Women) June 19, 2018

Hertha Marks Ayrton was a British mathematician and engineer. She earned her degree from @Cambridge_Uni in 1880, although she was only given a 'certificate' as Cambridge did not grant degrees to women at the time. #STEMlegends #WomenInSTEM pic.twitter.com/WIbzO6oIN4

— RAS Women in STEM (@RAS_Women) June 18, 2018

Ayrton’s certificate was upgraded to a degree by @UoLondon the following year. She went on to explain why public lights had a tendency to flicker in a series of journal articles for the Electrician and developed the Ayrton fan, which was used in the trenches of WW1.

— RAS Women in STEM (@RAS_Women) June 18, 2018

Ayrton became the first female member of @TheIET in 1899, and remained the only female member for the next 50 years. John Perry suggested Ayrton be accepted as a Fellow of @royalsociety, but the Council turned her application down on the basis that she was a married woman.

— RAS Women in STEM (@RAS_Women) June 18, 2018

Josephine Silone Yates was an American chemist. She became the first black woman to head a college science department while at Lincoln University. She became President of the Women's League of Kansas City in 1893 and President of @NACWC1896 in 1900. #STEMlegends #WomenInSTEM pic.twitter.com/OkxlrZncdt

— RAS Women in STEM (@RAS_Women) June 17, 2018

Sofia Kovalevskaya was a Russian mathematician. She moved to Germany in 1869 as women were not allowed to attend university in Russia. She first studied at @UniHeidelberg, under Hermann von Helmholtz, Gustav Kirchhoff, and Robert Bunsen. #STEMlegends #WomenInSTEM pic.twitter.com/7NlBy3UpOa

— RAS Women in STEM (@RAS_Women) June 16, 2018

Kovalevskaya gained her PhD in mathematics from the @uniGoettingen in 1874, although she was not allowed to attend lectures at the university. Kovalevskaya's thesis contained papers on partial differential equations, the dynamics of Saturn's rings, and elliptic integrals.

— RAS Women in STEM (@RAS_Women) June 16, 2018

Kovalevskaya was appointed editor of the mathematics journal 'Acta Mathematica' in 1884, and won the Prix Bordin of the French Academy of Science in 1888. The following year, she was appointed a Professor at @Stockholm_Uni.

— RAS Women in STEM (@RAS_Women) June 16, 2018

Kovalevskaya wrote 'Nihilist Girl', published in 1890. She may also be the first known LGBT+ woman to advance in mathematics, since she had a ‘romantic friendship’ with Swedish author Anne Charlotte Edgren-Leffler, which lasted until Kovalevskaya's death.

— RAS Women in STEM (@RAS_Women) June 16, 2018

Mary Emilie Holmes was an American geologist. She gained a PhD in earth sciences from @UMich in 1888 and became the first woman to be elected a Fellow of @geosociety. She was also an abolitionist and tried to establish schools for black people. #STEMlegends #WomenInSTEM pic.twitter.com/NcfbAQlWmj

— RAS Women in STEM (@RAS_Women) June 15, 2018

Ella Church was a British astronomer and one of the first women to become a Fellow of @RoyalAstroSoc in 1916. She was nominated by T. E. R. Phillips, who was director of the Jupiter section of @BritAstro and later became president of @RoyalAstroSoc. #STEMlegends #WomenInSTEM pic.twitter.com/ZIos83dqms

— RAS Women in STEM (@RAS_Women) June 14, 2018

Mary Adela Blagg was a British astronomer from Stoke-on-Trent. She worked on maps of the moon and on variable stars, with articles published in MNRAS. She was one of the first five women to be elected a Fellow of @RoyalAstroSoc. #STEMlegends #WomenInSTEM pic.twitter.com/seUZcE03wH

— RAS Women in STEM (@RAS_Women) June 13, 2018

Rebecca Cole was an American doctor. She gained her medical degree in 1867, becoming the second black American women to do so in the US. She was a pioneer in providing care to impoverished women and children and practised medicine for fifty years. #STEMlegends #WomenInSTEM pic.twitter.com/QpYaU2RKUQ

— RAS Women in STEM (@RAS_Women) June 12, 2018

Agnes Giberne was a British astronomer born in India in 1845. She was one of the founder-members of @BritAstro, which formed in 1890. Giberne wrote fiction as well as non-fiction including Sun, Moon and Stars: Astronomy for Beginners, published in 1879. #STEMlegends #WomenInSTEM pic.twitter.com/LmOsgoCnQQ

— RAS Women in STEM (@RAS_Women) June 11, 2018

Rebecca Lee Crumpler was an American doctor and author. She became the first black American woman to gain a medical degree in the US in 1864. She first practiced in Boston and moved to Virginia after the Civil War ended in 1865. #STEMlegends #WomenInSTEM pic.twitter.com/7CNTu3qgl8

— RAS Women in STEM (@RAS_Women) June 10, 2018

Crumpler primarily focused on women and children and worked for the Freedmen's Bureau to provide medical care to freed slaves. She published A Book of Medical Discourses in 1883, becoming the only female medical doctor to publish a book in the 19th century.

— RAS Women in STEM (@RAS_Women) June 10, 2018

Sarah Frances Whiting was an American astronomer. She became a professor of physics at @Wellesley in 1876, establishing the physics department and teaching practical courses in astronomy. One of her students was Annie Jump Cannon. #STEMlegends #WomenInSTEM pic.twitter.com/T19inQoVAq

— RAS Women in STEM (@RAS_Women) June 9, 2018

Annie Jump Cannon was an American astronomer. She gained a degree in physics from @Wellesley in 1884, but could not find work in her field until a decade later, when she became the assistant to Professor Sarah Frances Whiting. #STEMlegends #WomenInSTEM pic.twitter.com/DuBPiFE9qy

— RAS Women in STEM (@RAS_Women) June 8, 2018

In 1896, she was hired by @Harvard Observatory, where she met Henrietta Swan Leavitt, who, like Cannon, was also deaf. #STEMlegends #WomenInSTEM

— RAS Women in STEM (@RAS_Women) June 8, 2018

While at @Harvard, Cannon devised the system of stellar classification that we use today, by combining the methods of fellow computers Antonia Maury and Williamina Fleming. This is known as the Harvard Classification Scheme. #STEMlegends #WomenInSTEM

— RAS Women in STEM (@RAS_Women) June 8, 2018

Cannon also categorised over 230,000 stars, more than any other person, and discovered 300 variable stars and 5 novae. She was the first woman to receive an honorary doctorate from the @UniofOxford, and the first woman to be elected an officer of the @AAS_Office.

— RAS Women in STEM (@RAS_Women) June 8, 2018

Henrietta Swan Leavitt was an American astronomer. She graduated from @RadInstitute in 1893 and, after a bout of illness that left her deaf, she began working as a 'computer' at @Harvard Observatory under Edward Charles Pickering. #STEMlegends #WomenInSTEM pic.twitter.com/9PZkXYsOig

— RAS Women in STEM (@RAS_Women) June 7, 2018

Leavitt noticed a correlation between the pulsation periods of Cepheid variable stars, and their intrinsic luminosity. This could be used to determine how far away the stars are. Leavitt first published these results in 1908, and confirmed them in 1912. #STEMlegends #WomenInSTEM

— RAS Women in STEM (@RAS_Women) June 7, 2018

Cepheids were soon used to measure the size of the Milky Way and the distance to the Andromeda nebula. This led to acceptance of the idea that Andromeda is in fact another galaxy, outside of the Milky Way. #STEMlegends #WomenInSTEM

— RAS Women in STEM (@RAS_Women) June 7, 2018

In 1929, physicist Edwin Hubble used this method to show that the universe is expanding, and hence originated in a big bang. Leavitt was unable to make use of her discovery herself because women were not allowed to use telescopes of this calibre until the 1960s. #WomenInSTEM

— RAS Women in STEM (@RAS_Women) June 7, 2018

Mary Watson Whitney was an American astronomer. She studied as a 'guest' at @Harvard in the 1860s, since women could not be admitted at the time. She gained her master's degree at @Vassar in 1872, and later spent three years studying at Zurich. #STEMlegends #WomenInSTEM pic.twitter.com/YVbUf7yGTu

— RAS Women in STEM (@RAS_Women) June 6, 2018

Whitney became an assistant to Maria Mitchell at @Vassar and upon Mitchell's retirement in 1888, she became a Professor and was appointed Director of the Vassar Observatory. Over 100 scientific papers were published under her direction. #STEMlegends #WomenInSTEM

— RAS Women in STEM (@RAS_Women) June 6, 2018

Williamina Fleming was a British-American astronomer. While working @Harvard observatory, she helped implement a system of stellar classification based on spectroscopy, which was improved by Annie Jump Cannon, and is still used today. #STEMlegends #WomenInSTEM pic.twitter.com/6CvJx0bkLS

— RAS Women in STEM (@RAS_Women) June 5, 2018

Fleming went on to catalogue over 10,000 stars and discover 59 nebulae, 310 variable stars, and 10 novae. Fleming co-discovered the Horsehead Nebula, although she was not acknowledged at the time. She became an honorary member of @RoyalAstroSoc in 1906. #STEMlegends #WomenInSTEM

— RAS Women in STEM (@RAS_Women) June 5, 2018

Margaret Huggins was an Irish-English astronomer who helped pioneer the field of spectroscopy. She was the first to discover the nebulae inside the Orion Nebula is made of superheated oxygen gas, and became an honorary member of @RoyalAstroSoc in 1903. #STEMlegends #WomenInSTEM pic.twitter.com/SwNoZPCUCY

— RAS Women in STEM (@RAS_Women) June 4, 2018

Ellen Swallow Richards was an American chemist. She gained her first degree at @Vassar in 1870, when she became the first woman to study @MIT: "it being understood that her admission did not establish a precedent for the general admission of females". #STEMlegends #WomenInSTEM pic.twitter.com/u7jvKYlb6J

— RAS Women in STEM (@RAS_Women) June 3, 2018

Richards campaigned for women to have the right to a university education, and helped establish the @MIT Women's Laboratory in 1876. The laboratory closed in 1883, after @MIT began allowing women to undergo the same degree courses as men. #STEMlegends #WomenInSTEM

— RAS Women in STEM (@RAS_Women) June 3, 2018

Richards is known for developing Home Economics, where she argued that the work needed to run a home was vital to the economy. Richards applied her knowledge of chemistry to housework in order to improve sanitation and nutrition, and make the process quicker and easier.

— RAS Women in STEM (@RAS_Women) June 3, 2018

The invention of Home Economics meant women would have time for other pursuits, like education. Richards published The Chemistry of Cooking and Cleaning: A Manual for Housekeepers in 1882. She was appointed an instructor at MIT's first laboratory of sanitary chemistry in 1884.

— RAS Women in STEM (@RAS_Women) June 3, 2018

Richards surveyed the quality of water in Massachusetts in 1887. She showed that the scale of pollution was so bad that state water-quality standards were formed, and the first modern municipal sewage treatment plant was built in Massachusetts. #STEMlegends #WomenInSTEM

— RAS Women in STEM (@RAS_Women) June 3, 2018

Maria Mitchell was an American astronomer who set up her own school to teach girls science and mathematics when she was 17. In 1847, she discovered a comet, and she became the first female Professor of Astronomy in the United States in 1865. #STEMlegends #WomenInSTEM pic.twitter.com/erntL2mTC1

— RAS Women in STEM (@RAS_Women) June 2, 2018

Ada Lovelace was a British mathematician. She was the first to consider the concept of an operating system or software in 1842, while translating and annotating a critique of Charles Babbage's 'analytical engine', an early form of computer. #STEMlegends #WomenInSTEM pic.twitter.com/4OXA5wdNpr

— RAS Women in STEM (@RAS_Women) June 1, 2018

Lovelace's notes ended up being longer than the original text, and she wrote an algorithm for the analytical engine to compute Bernoulli numbers, which would have worked had the machine been built. #STEMlegends #WomenInSTEM

— RAS Women in STEM (@RAS_Women) June 1, 2018