Caroline Herschel: technician to the stars

Caroline Herschel (1750-1848)

Published in The Journal – the journal of the IST Autumn 2018

Caroline Herschel blazed a trail as the first salaried female in the history of astronomy. She gained fame in the 18th century as an assistant to her brother, the astronomer William Herschel, and later independent acclaim as a comet searcher. She was not the first technician drawn, initially reluctantly, from a famous astronomer’s family. Some years earlier, the wife of the first Astronomer Royal, Margaret Flamsteed, was also drafted in by her husband John to help with observations. However, where Margaret had a limited role in her husband’s work, advances in technology and Caroline’s burning desire for independence allowed Caroline to create a career for herself. The path to that career was not an easy one; hers was a turbulent life and one in which happiness was as difficult to find as the comets for which she hunted.

Caroline was born on 16th March 1750 into a working-class family and for the first 21 years of her life had little prospect of independence. Her hardworking and artistic father, Isaac, encouraged all his children to learn musical instruments and Caroline’s four brothers all became accomplished musicians. The second son, William, even followed his father into the Hanoverian Guards as a bandsman. However, Isaac’s attempts to teach Caroline music were overruled by her mother, Anna.

Caroline Herschel (1750-1848)
Figure 1: Caroline Herschel (1750-1848)

Caroline’s older sister had followed the typical career path of a working-class girl by going into service in a middle-class household. Unfortunately for Caroline, Anna liked the idea of having her youngest daughter as an unpaid servant, and so denied Caroline all opportunities to develop beyond basic schooling and the limited skills required at home such as basic knitting and linen-making. Caroline later wrote, “… all my father could do for me was to indulge me (and please himself) sometimes with a short lesson on the Violin; when my Mother was either in good humour or out of the way.”[1].

Escape through marriage was also unlikely for Caroline. A combination of scars caused by childhood smallpox and her small stature – she was less than 5ft in adulthood – meant that even her supportive father warned her against thoughts of marriage. An extensive diarist throughout her life, she recorded her father’s warning in her notebooks: “as I was neither handsome nor rich it was not likely that anyone would make me an offer, till perhaps when far advanced in life some old man might take me for my good qualities.”[1] Caroline felt that she was the Aschenbrödel [Cinderella] of the family.

The Invasion of Hanover by the French in 1757 would end up being an important event in Caroline’s life – even though she was only 7 at the time. The Hanoverian guard were defeated at the Battle of Hastenbeck forcing William, then aged 18, to flee to England. Fortunately, William made a success of his escape and after initially struggling to make a living as a concert performer, teacher, and composer William found a role, in 1766, as the organist at the fashionable Octagon Chapel in Bath. Five years later, William suggested that Caroline join him there. Caroline wrote that William proposed, “to make a trial, if by his instruction I might not become a useful singer for his winter Concerts and Oratorios?”[1] To release Caroline, William had to give Anna money to pay for a domestic servant.

On their night time journey to England, William talked of nothing but the constellations. It was the first clue, if Caroline had realised it at the time, that William was becoming obsessed with astronomy and that her true future lay in the stars above not as a star of the stage.

She arrived in England in 1973 aged 22, with no experience as a professional musician and speaking no English. William’s busy musical career and all-consuming hobby of astronomy reduced their interactions to breakfast-time lessons in household arithmetic, English, and singing. She was expected to run the household, fitting her singing practice in where she could. It was a lonely existence, but she was free of Anna and had a chance of independence. With characteristic determination, she made rapid progress and by 1776 her English had improved enough to allow her to assist William in preparing the treble singers for concerts, performing in concerts, and undertaking the time-consuming (and unpaid) role of copying sheet music.

Only five years after arriving in Bath, in 1777, Caroline sang as a soloist in the Easter oratorios with William conducting. The next year she sang solos from Handel’s Messiah with such success that that she was invited to repeat her performance in Birmingham. She refused, perhaps out of a sense of duty to her brother or a lack of confidence, preferring not to leave the protection of her brother as choir master. Whatever the reason, she turned down her only real chance to achieve independence as a musician.

Poster advertising Handel’s Messiah. Caroline appears as first soloist above the well known Miss Cantelo.
Figure 2: Poster advertising Handel’s Messiah. Caroline appears as first soloist above the well known Miss Cantelo. Herschel Family Archives. [1]

By that time, the Herschel home had already become an astronomer’s workshop and Caroline was expected to help. Her first role was making pasteboard tubes to hold the lenses for simple refracting telescopes. However, William’s obsession was to be able see things that no other observers had seen so Caroline was soon grinding horse dung to make mirror moulds used in the production of powerful reflecting telescopes. She would also read to her brother while he spent long hours polishing those mirrors and even spoon feed him like a baby so that he didn’t ruin the polish by stopping. She wrote of this time, “I became in time a useful member of the workshop as a boy might be to his master in the first year of his apprenticeship.”[2]

In 1776, William lost his position as organist in the Octagon Chapel – due in part to his obsession with astronomy. This meant that opportunities for Caroline diminished rapidly; her last concert as a soloist was on Whitsunday in 1782 at the age of 32. However, William’s telescopes had attracted many scientific admirers and some great early discoveries which catapulted him into a new life. It was his discovery of Uranus in 1781 that won him the patronage of King George III and started him on a career path that would see him become one of the greatest observational astronomers of all time.

In 1782, William moved to a house in Datchet near Windsor and took it for granted that Caroline would abandon her career, run his house, and act as his assistant. She was initially reluctant in this role, annoyed that she was now expected to spend her nights in the cold and wet outside looking through a telescope alongside running the house. Whether it was that Datchet was such a dull place, or that William went about properly teaching Caroline the skills of an astronomical assistant, she began to embrace her new role.

William had made Caroline her own telescope and instructed her to sweep the sky and record unusual objects such as double stars, comets, or nebulae, checking them against existing catalogues. The astronomical world at the time was obsessed by nebulae, so when Caroline started finding these with her small telescope brother and sister were excited. However, the French comet-hunting astronomer Charles Messier had already set down many nebulae and it was not until the evening of 26th February 1783 that Caroline came across a nebula which was unknown to science. She excitedly recorded in her notes: “Messier has it not.” This sparked William into a search for nebulae with his powerful new 20ft reflecting telescope.

William found that he could not do these searches alone and for the rest of the 1780s, William swept for nebulae and Caroline recorded what he saw. The next day Caroline would write up a fair copy of the night’s work, alongside polishing mirrors, winding clocks, writing down memorandums, and fetching and carrying instruments working with William’s other assistants. All this work meant she struggled to find time for her own sweeping.

She grabbed every opportunity open to her to continue her own work. In 1786, Caroline, aged 36, was stuck at home while William was away delivering a telescope in Germany. Between looking after the many uninvited-visitors who came to look through the telescopes, she pursued her own sweeping and discovered her first comet. Given the timing between the American and French revolutions, this must have been an important British scientific victory and William returned to England to find Caroline the centre of attention, both among the Royal Family at Windsor Castle and within English scientific circles. These years assisting William were productive and unusually happy years for Caroline and she supposed they would last for as many years as William continued in good health. This was not, however, to be.

In 1787, William was awarded £2000 to continue work on his giant 40ft telescope. As part of this award, Caroline wrote that King George III added, “a salary of 50 pounds per year was settled on me as an assistant to my Brother. [footnote: Exactly the sum I saved my brother at Bath in writing Music by a clean fireside.]”[2] Caroline had her independence, even if she’d had asked William to request this addition. The timing of this request cannot have been accidental as William married the widow Mary Pitt the following year.

William’s burgeoning relationship with Mary had been reducing the amount of time Caroline spent assisting William for the previous few years. Worse, in 1790, William solved what was for him the main riddle of the nebulae. Such was the power of his telescopes, he could show that some nebulae were clusters of stars while others were clouds from which stars might be born. This meant that William’s enthusiasm for late night observations diminished sharply and so Caroline’s role as William’s assistant was now greatly reduced. This was difficult for Caroline as it also left her without an outlet for her energies.

She used the time she had to search for comets and over the next decade she discovered eight comets, five of which were unknown to science. This put her third in the comet hunting league at the end of the 18th century behind two French male astronomers and she appeared in the popular press, not all together flatteringly, as “The Female Philosopher smelling out the Comet”. More happily, other astronomers seem to have treated Caroline as a professional colleague, if also something of a curiosity. She became friends with the Astronomer Royal Nevil Maskelyne and in a letter to him she revealed how much comet hunting meant to her, saying “I have no other means… of proving myself in the land of the living.”[3]

“The Female Philosopher smelling out the Comet”.
Figure 3: Etching dated February 1790 showing “The Female Philosopher smelling out the Comet”. Caroline had discovered a comet the previous month. From a private collection. [1]

Something happened between William, Mary, and Caroline in 1797 after the discovery of Caroline’s eighth comet. The details are lost to us but the event led to Caroline quitting her cottage next to the Herschel home and moving into very basic lodgings with one of William’s other assistants and his wife. From there she moved repeatedly, not staying anywhere for long, and struggled to find opportunities for observing. She was, however, far from inactive. In 1798, the Royal Society published her updated British catalogue of stars. It was a monumental effort requiring enormous dedication and flawless accuracy. It contained almost 3000 stars of which Caroline and William had together contributed nearly 600. Despite this success, Caroline became lonely and frustrated by the lack of employment and she began to plan a return to Hanover.

William died in 1822 and with the end of his life, Caroline ended her time in England. Aged 72, she left England with fond farewells, but did not retire from astronomy as she kept track of astronomical discoveries and took great joy in creating a full catalogue of the 2500 nebulae then known – an achievement that gained her the Royal Astronomical Society’s gold medal. She was the first woman to receive this award and was not joined by another woman until Jocelyn Bell Burnell’s recognition in 1989.

Despite her continued successes, her writings at this time became notably bitter and maudlin about the missed opportunities of her life. Publicly, Caroline seemed embarrassed by the many public honours she received, saying that she “did nothing for [her] Brother than what a well-trained puppy Dog would have done”[2].

She remained, however, proud of her achievements, and prepared the following as part of the epitaph for her gravestone: “The gaze of the deceased here below, was turned to the starry heavens; her own discovery of comets and her share in the immortal labours of her brother, William Herschel will testify hereof to future generations.”[3] These words would ultimately adorn her final resting place in 1848, after her death at the age of 98.

Timeline of Caroline Herschel’s life.
Figure 4: Timeline of Caroline Herschel’s life.


[1] M. Hoskin, Caroline Herschel’s Life of “Mortifications and disappointments”, JHA, 45(4), 2014, p442-466.

[2] C. Brock, The Comet Sweeper, Icon Books, 2007.

[3] M Bruck, Women in Early British and Irish Astronomy, Springer, 2009

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