In the fall of 1847, Mitchell gazed out at the night sky with a telescope, and spotted a comet just five degrees above Polaris (the North Star). She wrote down the comet's coordinates, and her father gave this information to Harvard's Professor William Bond on her behalf. A year later, Denmark's Christian VIII (the eighth) recognized Mitchell with a gold medal as the first person to view a comet through a telescope. The comet was then named "Miss Mitchell's Comet" in her honor.
Following Mitchell's recognized discovery of the comet by telescope in 1848, the American Academy of Arts and Sciences (AAAS) voted her into their group as the first female member. In 1849, she was then commissioned to work with the United States Nautical Almanac Office (USNAO) to compute tables regarding the positions of the planet of Venus. A year later, the Association for the Advancement of Science also made her their first female member.
In 1865, Mitchell became the first professor of astronomy, and director of the college observatory, at the just-opened Vassar College in Poughkeepsie, New York, where she continued her pioneering work as a female astronomer by using her 12-inch telescope to watch meteor showers, document the surface features of the planets of Jupiter and Saturn and otherwise study the stars. In 1873, she founded the American Association for the Advancement of Women (AAAW) to help promote human rights throughout the United States, and she was its president from 1874 to 1876.
In 1873, Mitchell was a part of the first meeting of the Women's Congress, featuring other prominent women's right activists at the time, such as Elizabeth Cady Stanton, Susan B. Anthony, Lucy Stone, Elizabeth Blackwell and Antoinette Brown Blackwell. Following her death in 1888, she was elected to the Hall of Fame of Great Americans (HOFGA) at New York University in 1905. She also was elected to the National Women's Hall of Fame in Seneca Falls, New York, in 1994 for her inventions and pioneering in astronomy, science and women's rights.