Caroline Lucretia Herschel (/ˈhɜːrʃəl, ˈhɛər-/; 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
throughout her career.
She was the first woman to receive a salary as a
scientist. She was the first woman in England to hold a
government position. She was the first
woman 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 also 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).
Early life
Caroline Lucretia Herschel was born in the town of Hanover
on 16 March 1750. She was the eighth child and fourth daughter of Isaac
Herschel, a self-taught oboist, and his wife, Anna Ilse Moritzen. Isaac 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 (part of 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, was sixteen years older, and the only
surviving girl besides Caroline. She married when Caroline was five, meaning
that the younger girl was 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 mostly successful with
the boys.
At the age of ten, Caroline was struck with typhus, which
stunted her growth, such that she never grew taller than 4 feet 3 inches (1.30
m). She suffered vision loss in her left
eye as a result of her illness. Her
family assumed that she would never marry and her mother felt it was best for
her to train to be a house servant rather than becoming educated in accordance
with her father's wishes. 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 more
advanced needlework than what 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 16 August 1772 after her brother's intervention 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 organizing public concerts.
Caroline did not blend in with 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.
Transition to
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 a
shambles and were critically panned.
Astronomical career
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.
On 28 August 1782 Caroline initiated her first record book.
She inscribed the first three opening pages: "This is what I call the Bills
& Rec.ds of my Comets", "Comets and Letters", and
"Books of Observations". This, along with two subsequent books,
currently belongs to the Herschel trove at the Royal Astronomical Society in
London.
On 26 February 1783, Caroline made her first discovery: she
had found a nebula that was not included in the Messier catalogue. That same
night, she independently discovered Messier 110 (NGC 205), the second companion
of the Andromeda Galaxy. William then began to search himself for nebulae,
sensing that there were many discoveries to be made. Caroline was relegated to
a ladder on William's 20-foot reflector, attempting impossible measurements of
double stars. William quickly realized his method of searching for nebulae was
inefficient and he required an assistant to keep records. Naturally, he turned
to Caroline.
"But it was not
til the last two months of the same year before I felt the least encouragement
for spending the starlight nights on a grass-plot covered with dew or hoar
frost without a human being near enough to be within call."
In the summer of 1783, William finished building a
comet-searching telescope for Caroline, which she began to use immediately.[10]
Beginning in October 1783, the Herschels used a 20-foot reflecting telescope to
search for nebulae. Initially, William attempted to both observe and record
objects, but this too was inefficient and he again turned to Caroline. She sat
by a window inside, William shouted his observations, and Caroline recorded.
This was not a simple clerical task, however, because she would have to use
John Flamsteed's catalogue to identify the star William used as a reference
point for the nebulae. Because Flamsteed's catalogue was organized by
constellation, it was less useful to the Herschels, so Caroline created her own
catalogue organized by north polar distance. The following morning, Caroline would go over
her notes and write up formal observations, which she called "minding the
heavens."
Comets
During 1786–97 she discovered eight comets, the first on 1
August 1786. She had unquestioned priority as discoverer of five of the comets
and rediscovered Comet Encke in 1795. Five of her comets were published in
Philosophical Transactions. A packet of paper bearing the superscription,
"This is what I call the Bills and Receipts of my Comets" contains
some data connected with the discovery of each of these objects. William was
summoned to Windsor Castle to demonstrate Caroline's comet to the royal family.
William recorded this phenomenon, himself, terming it "My Sister's Comet."
Caroline Herschel is often credited as
the first woman to discover a comet; however, Maria Kirch discovered a comet in
the early 1700s, but is often overlooked because at the time, the discovery was
attributed to her husband, Gottfried Kirch.
She wrote a letter to the Astronomer Royal to announce the
discovery of her second comet. The third comet was discovered on 7 January
1790, and the fourth one on 17 April 1790. She announced both of these to Sir
Joseph Banks, and all were discovered with her 1783 telescope. In 1791, Caroline began to use a 9-inch telescope
for her comet-searching, and discovered three more comets with this instrument.
Her fifth comet was discovered on 15
December 1791 and the sixth on 7 October 1795. Caroline wrote in her journal
during this time "My brother wrote an account of it to Sir J. Banks, Dr.
Maskelyne, and to several astronomical correspondents" for the discovery
of her fifth comet. Two years later, her eighth and last comet was discovered
on 6 August 1797, the only comet she discovered without optical aid. She announced this discovery by sending a
letter to Banks. In 1787, she was
granted an annual salary of £50 (equivalent to £6,200 in 2019) by George III
for her work as William's assistant. Caroline's appointment made her the first
woman in England honored with an official government position, and the first
woman to be paid for her work in astronomy.
In 1797 William's observations had shown that there were a
great many discrepancies in the star catalogue published by John Flamsteed,
which was difficult to use because it had been published as two volumes, the
catalogue proper and a volume of original observations, and contained many
errors. William realised that he needed a proper cross-index to properly
explore these differences but was reluctant to devote time to it at the expense
of his more interesting astronomical activities. He therefore recommended to
Caroline that she undertake the task, which ultimately took 20 months. The
resulting Catalogue of Nebulae and Clusters of Stars was published by the Royal
Society in 1798 and contained an index of every observation of every star made
by Flamsteed, a list of errata, and a list of more than 560 stars that had not
been included. In 1825, Caroline donated
the works of Flamsteed to the Royal Academy of Göttingen.
Relationship with
William
Throughout her writings, she repeatedly made it clear that
she desired to earn an independent wage and be able to support herself. When
the crown began paying her for her assistance to her brother in 1787, she
became the first woman—at a time when even men rarely received wages for
scientific enterprises—to receive a salary for services to science.[3] Her
pension was £50 a year, and it was the first money that Caroline had ever
earned in her own right.
When William married a rich widow, Mary Pitt (née Baldwin)
in 1788, the union caused tension in the brother-sister relationship. Caroline
has been referred to as a bitter, jealous woman who worshipped her brother and
resented those who invaded their domestic lives. In his book The Age of Wonder, Richard Holmes
is more sympathetic to Caroline's position, noting that the change was in many
respects negative for Caroline. With the arrival of William's wife, Caroline
lost her managerial and social responsibilities in the household and
accompanying status. She also moved from the house to external lodgings,
returning daily to work with her brother. She no longer held the keys to the
observatory and workroom, where she had done much of her own work. Because she
destroyed her journals from 1788 to 1798, her feelings about the period are not
entirely known. In August 1799, Caroline was independently recognized for her
work, when she spent a week in Greenwich as a guest of the royal family.
Barthélemy Faujas de Saint-Fond indicated she and her
brother continued working well during this period. When her brother and his
family were away from home, she often returned there to take care of it for
them. In later life, she and Lady Herschel exchanged affectionate letters, and
she became deeply attached to her nephew, astronomer John Herschel.
William's marriage likely led to Caroline's becoming more
independent of her brother and more a figure in her own right. Caroline made many discoveries independently
of William and continued to work solo on many of the astronomical projects
which contributed to her rise to fame.
New General Catalogue
In 1802, the Royal Society published Caroline's catalogue in
its Philosophical Transactions of the Royal Society A under William's name.
This listed around 500 new nebulae and clusters to the already known
2,000. Toward the end of Caroline's life, she
arranged two-and-a-half thousand nebulae and star clusters into zones of
similar polar distances so that her nephew, John Herschel, could re-examine
them systematically. The list was eventually enlarged and renamed the New
General Catalogue. Many non-stellar objects are still identified by their NGC
number.
Later life and legacy
After her brother died in 1822, Caroline was grief-stricken
and moved back to Hanover, Germany, continuing her astronomical studies to
verify and confirm William's findings and producing a catalogue of nebulae to
assist her nephew John Herschel in his work. However, her observations were
hampered by the architecture in Hanover, and she spent most of her time working
on the catalogue. In 1828 the Royal
Astronomical Society presented her with their Gold Medal for this work—no woman
would be awarded it again until Vera Rubin in 1996. Upon
William's death, her nephew, John Herschel, took over observing at Slough.
Caroline had given him his first introduction into astronomy, when she showed
him the constellations in Flamsteed's Atlas. Caroline added her final entry to
her observing book on 31 January 1824 about the Great Comet of 1832, which had
already been discovered on 29 December 1823.
Throughout the twilight of her
life, Caroline remained physically active and healthy, and regularly socialized
with other scientific luminaries. She spent her last years writing her memoirs
and lamenting her body's limitations, which kept her from making any more
original discoveries.
Caroline Herschel died peacefully in Hanover on 9 January
1848. She is buried at 35 Marienstrasse in Hanover at the cemetery of the
Gartengemeinde, next to her parents and with a lock of William's hair. Her
tombstone inscription reads, "The eyes of her who is glorified here below
turned to the starry heavens." With her brother, she discovered over 2,400
astronomical objects over twenty years. The asteroid 281 Lucretia (discovered 1888)
was named after Caroline's second given name, and the crater C. Herschel on the
Moon is named after her.
Adrienne Rich's 1968 poem "Planetarium" celebrates
Caroline Herschel's life and scientific achievements. The artwork The Dinner Party, which celebrates
historical women who have made extraordinary contributions, features a place setting
for Caroline Herschel. Google honored her with a Google Doodle on her
266th birthday (16 March 2016).
Honors
Herschel was honored by the King of Prussia and the Royal
Astronomical Society. The gold medal
from the Astronomical Society was awarded to her in 1828 "for her recent
reduction, to January, 1800, of the [2,500] Nebulæ discovered by her
illustrious brother, which may be considered as the completion of a series of
exertions probably unparalleled either in magnitude or importance in the annals
of astronomical labour." She completed this work after her brother's death
and her move to Hanover.
The Royal Astronomical Society elected her an Honorary
Member in 1835, along with Mary Somerville; they were the first women members.
She was also elected as an honorary member of the Royal Irish Academy in Dublin
in 1838.
In 1846, at the age of 96, she was awarded a Gold Medal for
Science by the King of Prussia, conveyed to her by Alexander von Humboldt,
"in recognition of the valuable services rendered to Astronomy by you, as
the fellow-worker of your immortal brother, Sir William Herschel, by
discoveries, observations, and laborious calculations".
Asteroid 281 Lucretia is named in her honor.
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