Caroline Herschel is mainly known to history as the sister of the astronomer William Herschel, the discoverer of the planet Uranus, but she was an astronomer in her own right - she was elected as an honorary¹ member of the Royal Astronomical Society in 1835.

A Difficult Childhood

Caroline Lucretia Herschel was born on 16 March, 1750, in Hanover. Her father Isaac was a musician - he worked as a military bandmaster - but he also had an interest in astronomy, so he introduced his children to the delights of the night sky. Caroline did not receive the best education in those days. She developed pock-marked skin after contracting smallpox, and grew to an adult height of just 4ft 3in (1.3m) after having caught typhus at the age of ten. Her mother thought she would only be fit for working as a domestic servant.

After her father died in 1767, Caroline took lessons in dressmaking and tried to qualify as a governess at the same time as caring for her mother. Her older brother William moved to England after having survived a stint in the military, taking advantage of the fact that Hanover shared its Head of State with Britain. Caroline joined him there in 1772 in spite of her mother's protestations. She looked after William, but also took lessons from him in music and singing - he was working as an organist and conductor in Bath. Caroline sometimes sang in concerts (but only ones where William was the conductor). When William turned his interest to astronomy, she ably assisted him and eventually began making discoveries of her own.

Astronomy

Caroline assisted William with making reflecting telescopes and William helped her to learn spherical trigonometry so that she could do calculations for him as well. When she wasn't busy working for William, she would scan the night sky herself. On one occasion stargazing with her father, Caroline had seen a comet. During her astronomical career she would go on to discover eight new comets. She saw her first one on 1 August, 1786. While two were named after men who discovered the same comets independently, Caroline gave her name to six². She also spotted nebulae and star clusters.

William had discovered Uranus in 1781 and King George III awarded him a salary of £200 per year as Court Astronomer. In 1787 Caroline was also awarded a salary by George III - she received £50 per year as an Assistant to the Court Astronomer.

Catalogue

In 1786 the siblings moved to Slough, and named their home 'Observatory House'. Caroline moved out of Observatory House when William married in 1788, but she continued to work with William there during the day.

William had worked with Flamsteed's star catalogue Historia Coelestis and in 1783 he had submitted data to the Royal Society to record a number of stars that he observed but which had not been included in the catalogue. In 1798 Caroline submitted to the Royal Society her Index to Flamsteed's Observations of the Fixed Stars, which included 560 previously-omitted stars.

William's son John was born in 1792. Caroline spent time with John and played a role in his education, helping him to learn physics and chemistry as well as music and astronomy. In 1802 William had published a catalogue of 500 nebulae. To assist with John's astronomical education, Caroline built on this work. William died in 1822 and Caroline moved back to Hanover, but by 1828 she had produced a catalogue of 2,500 nebulae.

Renown

In recognition of her work, Caroline was awarded a Gold Medal by the Royal Astronomical Society. She became an honorary member of the Royal Astronomical Society in 1835³ and an honorary member of the Royal Irish Academy in 1838.

She was also recognised by important people. She met noted mathematician and astronomer Carl Friedrich Gauss in 1824 after having corresponded with him for a number of years. She had visited members of the British Royal Family when she lived in England and was visited by a Prussian Prince in Hanover. She was awarded the Large Gold Medal for Science by the King of Prussia in 1846.

I cannot express how much I feel happy of having made the personal acquaintance [of one] whose rare zeal and distinguished talents for science are paralleled by the amiability of her character.
- Gauss, in a letter to Caroline Herschel from Göttingen, 28 September, 1825

Caroline Lucretia Herschel died on 9 January, 1848, at the age of 97. Asteroid 281 was named Lucretia in her honour in 1889, and there is a crater on the Moon named C. Herschel. Thus the diminutive assistant to Sir William Herschel has a place in history as 'The First Lady of Astronomy'.

Image courtesy of NASA.