On the evening of August 1, 1786, Caroline Herschel ascended the roof of her house to sweep the night sky for nebulae using a small telescope that her famous brother William had given her three weeks before.
She had already noted a handful of objects missed by the famous Charles Messier in his quest for comets. That evening, she got the perfect reward for her diligence by discovering a comet, an achievement that propelled her to worldwide fame. Distinguished visitors descended on the Herschel household to congratulate Caroline. The Astronomer Royal regarded her discovery as exceptionally important for the nation because Messier in Paris had hitherto led the field.
Herschel's life had an unpromising start. She was born in Hanover in 1750, one of ten children. Her childhood illnesses included smallpox and typhus, which left her slightly disfigured and of small stature. Her father pronounced the teenage Herschel unmarriageable. He did, however, take pride in the musical talents of all of his children, and he encouraged them to observe the natural world. Herschel always remembered her father's eagerness when he showed her an eclipse of the sun safely reflected in a tub of water. She was 14 at the time and destined for a life of unpaid domestic drudgery.
To better his own musical career, William moved from Hanover to Bath, where he quickly made a name for himself, becoming organist at the fashionable Octagon Chapel. In 1772, Herschel joined William and two brothers in Bath, ostensibly to train as a singer, but partly to act as housekeeper. She excelled as a soprano soloist, but by the time her career looked secure, William became obsessed with astron-omy. Soon he was pressing her to help with the construction of telescopes and the recording of his observations.
The family's fortunes changed dramatically in 1781 when William discovered the planet Uranus, which he named Georgium Sidus to curry favour with George III. The trick worked: the king appointed him a royal astronomer at Windsor, with a salary and funding for the construction of ever-larger telescopes. Herschel now found herself engaged without pay as his full time scientific assistant.
William embarked on a huge research programme to catalogue the nebulae, which he would never have accomplished but for Herschel, because she had to write times and positions by candlelight, shouted to her by William at the eyepiece. She had no time to make her own observations if William was at home.
When George III presented a Herschel telescope to an observatory in Hanover, its delivery took William away from home for a few weeks, which gave Herschel the opportunity to commence her comet search. When she announced her success, a fresh wave of visitors descended on the household.
The laborious cataloguing work she had carried out on behalf of her brother thus became more widely known. When George III granted her a salary of Pounds 50 she became the first woman in the history of science to be paid as an astronomer.
Claire Brock's account of this incredible woman succeeds admirably in restoring Herschel's astronomical reputation. In this she has been aided by the Herschel scholar Michael Hoskin, who recently edited Caroline's two autobiographies. Brock's account could, however, have been fuller by setting the Herschels in an intellectual landscape. There is not enough on the status of astronomical knowledge in the Enlightenment. Nor are we told how the achievements of the Herschel family related to the progress being made by their contemporaries.
Simon Mitton is a fellow of St Edmund's College, Cambridge.
The Comet Sweeper: Caroline Herschel's Astronomical Ambition
Author - Claire Brock
Publisher - Icon Books
Pages - 208
Price - £9.99
ISBN - 9781840467208