Caroline Lucretia Herschel ( HUR-shəl, HAIR-shəl, German: [kaʁoˈliːnə ˈhɛʁʃl̩]; 16 March 1750 – 9 January 1848) was a German astronomer, whose most significant contributions to astronomy were the discoveries of several comets, including the periodic comet 35P/Herschel–Rigollet, which bears her name. She was the younger sister of astronomer William Herschel, with whom she worked for most of her career.
She was the first known professional female astronomer, and the first woman to receive a salary as a scientist, and the first woman in England to hold a government position. She was also the first woman to publish scientific findings in the Philosophical Transactions of the Royal Society, to be awarded a Gold Medal of the Royal Astronomical Society (1828), and to be named an honorary Member of the Royal Astronomical Society (1835, with Mary Somerville). She was named an honorary member of the Royal Irish Academy (1838). The King of Prussia presented her with a gold medal for Science on the occasion of her 96th birthday (1846).
Caroline Lucretia Herschel was born in the town of Hanover, Germany on 16 March 1750. She was the eighth child and fourth daughter of Isaac Herschel (1707–1767), a self-taught oboist, and his wife, Anna Ilse Moritzen (1710–1789). The Herschel family originated from Pirna in Saxony, near Dresden. Isaak became a bandmaster in the Hanoverian Foot Guards, whom he first joined in 1731, and was away with his regiment for substantial periods. He became ill after the Battle of Dettingen (in the War of the Austrian Succession) in 1743 and never recovered fully; he suffered a weak constitution, chronic pain, and asthma for the remainder of his life. The oldest of their daughters, Sophia Elizabeth Herschel (1733–1803), was sixteen years older, and the only surviving girl besides Caroline. She married violinist Joachim Heinrich Griesbach (1730–1773) when Caroline was five, which resulted in the younger girl being tasked with much of the household drudgery. Caroline and the other children received a cursory education, learning to read and write and little more. Her father attempted to educate her at home but his efforts were more successful with the boys.
At the age of ten Caroline was struck with a severe case of typhus, which so stunted her growth that she never grew more than 4 feet 3 inches (1.30 m) tall; she also lost vision in her right eye as a result of the illness. Her family assumed that she would never marry and her mother thought it better that she train to be a house servant than be educated in accordance with her father's wishes. However, her father sometimes took advantage of her mother's absence by tutoring her individually, or including her in her brother's lessons, such as violin. Caroline was briefly allowed to learn dress-making. Though she learned to do needlework from a neighbour, her efforts were stymied by long hours of household chores. To prevent her from becoming a governess and earning her independence that way, she was forbidden to learn French or needlework any more advanced than the skills she could pick up from neighbours.
Following her father's death, her brothers William and Alexander proposed that she join them in Bath, England, to have a trial period as a singer for musician brother William's church performances. Caroline eventually left Hanover on 15 August 1772 after her brothers intervened with their recalcitrant mother. On the journey to England, she was first introduced to astronomy by way of the constellations and opticians' shops.
In Bath, she took on the responsibilities of running William's household, and began learning to sing. William had established himself as an organist and music teacher at 19 New King Street, Bath (now the Herschel Museum of Astronomy). He was also the choirmaster of the Octagon Chapel. William was busy with his musical career and became fairly busy organising public concerts.
Caroline did not blend into the local society and made few friends, but was finally able to indulge her desire to learn, and took regular singing, English, and arithmetic lessons from her brother, and dance lessons from a local teacher. She also learned to play the harpsichord, and eventually became an integral part in William's musical performances at small gatherings. She became the principal singer at his oratorio concerts, and acquired such a reputation as a vocalist that she was offered an engagement for the Birmingham festival after a performance of Handel's Messiah in April 1778, where she was the first soloist. She declined to sing for any conductor but William, and after that performance, her career as a singer began to decline. Caroline was subsequently replaced as a performer by distinguished soloists from outside the area because William wished to spend less time in rehearsals to focus on astronomy.
When William became increasingly interested in astronomy, transforming himself from a musician to an astronomer, Caroline again supported his efforts. She said somewhat bitterly, in her Memoir, "I did nothing for my brother but what a well-trained puppy dog would have done, that is to say, I did what he commanded me." Ultimately, though, she became interested in astronomy and enjoyed her work.
In the 1770s, as William became more interested in astronomy, he started to build his own telescopes from lenses he had ground, unhappy with the quality of lenses he was able to purchase. Caroline would feed him and read to him as he worked, despite her desire to burnish her career as a professional singer.
She became a significant astronomer in her own right as a result of her collaboration with him. The Herschels moved to a new house in March 1781 after their millinery business failed, and Caroline was guarding the leftover stock on 13 March, the night that William discovered the planet Uranus. Though he mistook it for a comet, his discovery proved the superiority of his new telescope. Caroline and William gave their last musical performance in 1782, when her brother accepted the private office of court astronomer to King George III; the last few months of their musical career had been in shambles and were critically panned.
First discoveries and catalogue
William's interest in astronomy started as a hobby to pass time at night. At breakfast the next day he would give an impromptu lecture on what he had learned the night before. Caroline became as interested as William, stating that she was "much hindered in my practice by my help being continually wanted in the execution of the various astronomical contrivances." William became known for his work on high performance telescopes, and Caroline found herself supporting his efforts. Caroline spent many hours polishing mirrors and mounting telescopes in order to maximize the amount of light captured. She learned to copy astronomical catalogues and other publications that William had borrowed. She also learned to record, reduce, and organize her brother's astronomical observations. She recognized that this work demanded speed, precision and accuracy.
Caroline was asked to move from the high culture of Bath to the relative backwater of Datchet in 1782, a small town near Windsor Castle where William would be on hand to entertain royal guests. He presumed that Caroline would become his assistant, a role she did not initially accept. She was unhappy with the accommodations they had taken; the house they rented for three years had a leaky ceiling and Caroline described it as "the ruins of a place". She was also aghast at the prices in the city and the fact that their domestic servant was imprisoned for theft at the time of her arrival. While William worked on a catalogue of 3,000 stars, studied double stars, and attempted to discover the cause of Mira's and Algol's variability, Caroline was asked to "sweep" the sky, meticulously moving through the sky in strips to search for interesting objects. She was unhappy with this task at the beginning of her work, longing for the culture of Bath and feeling isolated and lonely, but gradually developed a love for the work.