“If I were king,” the trailblazing mathematician Émilie du Châtelet wrote in the 1730s, “I would reform an abuse that cuts out, so to speak, half of humanity. I would allow women to share in all the rights of humanity, and most of all those of the mind.” It took a century for her fantasy to take on the first glimmer of reality.

In 1835, a quarter century before Maria Mitchell earned her place as America’s first woman astronomer and led the way for women in science, Caroline Herschel (March 16, 1750–January 9, 1848) became the world’s first professional woman astronomer. Together with the Scottish mathematician Mary Somerville (for whom the word “scientist” had been coined a year earlier), 85-year-old Herschel became the first woman elected Honorary Member of the Royal Astronomical Society for the eight comets she had discovered in her prolific life as a “sweeper” of the stars.

Herschel’s monumental legacy and her ninety-eight years of earthly perseverance — a lifespan that exceeded the era’s average life expectancy by decades and stretched through the French Revolution, the Civil War, the rise and fall of Napoleon, and the invention of the railroad and the telegraph — are all the more impressive against the backdrop of the inordinate hardships she had to overcome from a young age.

Of her ten siblings, four died in early childhood. At the age of eleven, Caroline contracted typhus fever, which nearly killed her. She would later recount the aftermath of the attack in Memoir and Correspondence of Caroline Herschel (public library):

For several months after I was obliged to mount the stairs on my hands and feet like an infant; but here I will remark that from that time to this present day [at age 71] I do not remember ever to have spent a whole day in bed.

The illness damaged her left eye and stunted her growth. For the remainder of her life, this tiny woman of four feet and three inches swept the skies with her twenty-foot Newtonian telescope and one good eye.

But many more obstacles stood between her and astronomy, perhaps most crucially her mother — an illiterate woman who was determined to make Caroline useful in domestic duties and was adamant that the girl shouldn’t be distracted with education. It was the father, an admirer of astronomy, who secretly taught her music and science when his wife was “either in good humour or out of the way,” and who one frosty night took young Caroline out to make her “acquainted with several of the most beautiful constellations [and] a comet which was then visible.”

He eventually arranged for her to be tutored by a young woman whose parents lived in the same Hanover house as the Herschels. To receive her lessons, Caroline would rise before dawn, meet her tutor at daybreak, and study until 7 in the morning, at which point she would have to resume her duties as the household’s Cinderella. But this faint promise of scholarship barely lasted a few months — tuberculosis claimed her young tutor’s life.

The summer after Caroline’s sixteenth birthday, her father had a stroke, which paralyzed the entire left side of his body. He died several months later, leaving the young woman in stupefied grief. To alleviate her mourning, her brothers William and Alexander suggested that she join them in Bath, England, where William, to whom she was deeply and abidingly attached, had taken a position as an organist at a local church. William beseeched and beseeched, but the mother was unyielding. In a bout of desperation, Caroline knitted two years’ worth of stockings for the family to stave them off in her absence. Mrs. Herschel finally relented and Caroline set out for England.

Caroline joined William with the intention of training as a singer so that she could accompany him in concerts. But although she became an accomplished vocalist, her loyalty to William, at that point and ever after, was so great that when she was invited to perform at a prestigious festival, she declined on the grounds that she never wanted to sing in concerts where her brother wasn’t the conductor.

It was in Bath that William grew increasingly enamored with the cosmos, until he decided to limit his work as a music teacher and focus on his newfound love of astronomy. Too poor to afford instruments and too proud to ask for loans, he taught himself to make mirrors and build telescopes, and Caroline became his steadfast assistant in celestial observations.

She recounts:

I was obliged to read to him whilst he was at the turning lathe, or polishing mirrors, Don Quixote, Arabian Nights’ Entertainment, the novels of Sterne, Fielding, &c.; serving tea and supper without interrupting the work with which he was engaged … and sometimes lending a hand. I became in time as useful a member of the workshop as a boy might be to his master in the first year of his apprenticeship.

[…]

When I found that a hand was sometimes wanted when any particular measures were to be made with the lamp micrometer, &c., or a fire to be kept up, or a dish of coffee necessary during a long night’s watching, I undertook with pleasure what others might have thought a hardship.

William enlisted her assistance “to run the clocks, write down a memorandum, fetch and carry instruments, or measure the ground with poles” — a line Adrienne Rich would later incorporate into her tribute to Caroline. When one of his telescope mirrors had to be cast in a mould of loam made from horse dung, Caroline faithfully pounded vast quantities of manure in a mortar and spent hours sifting it through a fine sieve.

When she learned to copy star catalogs — painstaking work that consumed countless days — she started to notice gaps in the data. Feeling compelled to remedy them, she began making her own observations. In the summer of 1782, at the age of thirty-two, Herschel embarked on her own catalog and made her first independent discoveries the following year — a nebula missing from the famous Messier catalog and, crucially, the dwarf elliptical galaxy now known as Messier 110, a companion to the Andromeda Galaxy.

Herschel not only devoted her life to astronomy but nearly lost it to the passion for observation. In a diary entry from the summer of her first discoveries, she recounts a most improbable incident, at once gory and glorious in its attestation to her selfless heroism in the name of science. She writes on July 8, 1783, shortly after she and her brother built a new Newtonian telescope:

My brother began his series of sweeps when the instrument was yet in a very unfinished state, and my feelings were not very comfortable when every moment I was alarmed by a crack or fall, knowing him to be elevated fifteen feet or more on a temporary cross-beam instead of a safe gallery. The ladders had not even their braces at the bottom; and one night, in a very high wind, he had hardly touched the ground before the whole apparatus came down. Some labouring men were called up to help in extricating the mirror, which was fortunately uninjured, but much work was cut out for carpenters next day.

That my fears of danger and accidents were not wholly imaginary, I had an unlucky proof on the night of the 31st December. The evening had been cloudy, but about ten o’clock a few stars became visible, and in the greatest hurry all was got ready for observing. My brother, at the front of the telescope, directed me to make some alteration in the lateral motion, which was done by machinery, on which the point of support of the tube and mirror rested. At each end of the machine or trough was an iron hook, such as butchers use for hanging their joints upon, and having to run in the dark on ground covered a foot deep with melting snow, I fell on one of these hooks, which entered my right leg above the knee. My brother’s call, “Make haste!” I could only answer by a pitiful cry, “I am hooked!” He and the workmen were instantly with me, but they could not lift me without leaving nearly two ounces of my flesh behind. The workman’s wife was called, but was afraid to do anything, and I was obliged to be my own surgeon by applying aquabusade and tying a kerchief about it for some days, till Dr. Lind, hearing of my accident, brought me ointment and lint, and told me how to use them.

That same Dr. Lind remarked that “if a soldier had met with such a hurt he would have been entitled to six weeks’ nursing in a hospital,” but Herschel soldiered on with complete composure and continued making observations despite her injury. She concludes the diary entry with charming matter-of-factliness that bespeaks her superhuman devotion to science:

To make observations with such large machinery, where all around is in darkness, is not unattended with danger, especially when personal safety is the last thing with which the mind is occupied.

The heroic incident was memorialized nearly two centuries later in a portion of Alfred Noyes’s lengthy poem “Sir John Herschel Remembers,” from his 1922 collection Watchers of the Sky. The poem’s protagonist — the great astronomer and inventor John Herschel, son of William, nephew of Caroline — remembers how his aunt’s intrepid devotion to astronomy inspired his own:

He saw her in mid-winter, hurrying out,
A slim shawled figure through the drifted snow,
To help him; saw her fall with a stifled cry,
Gashing herself upon that buried hook,
And struggling up, out of the blood-stained drift,
To greet him with a smile.
“For any soldier,
This wound,” the surgeon muttered, “would have meant
Six weeks in hospital.”
Not six days for her!
“I am glad these nights were cloudy, and we lost
So little,” was all she said.

Complement Herschel’s Memoir and Correspondence with trailblazing astronomer Maria Mitchell on the art of knowing what to do with one’s life, this illustrated celebration of trailblazing women in science, and the story of how Harvard’s unsung 19th-century female astronomers revolutionized our understanding of the universe decades before women could vote.