May 19, 2018

“William and Caroline Herschel: Partners in Exploration” – History of Astronomy Meeting – 24th April 2018

Mona Evans

Report by: Bobby Manoo

“We live in very exciting times for Astronomy but what we know now was built on the discoveries of the seekers of knowledge of the past who pushed the boundaries of what was known in their time”.

This was how Mona Evans opened her presentation for the evening as she began her talk about the brother and sister partnership, William and Caroline Herschel.

Mona is currently the Astronomy Editor of BellaOnline – The Voice of Women. She holds an M.Sc. in Astronomy from Swinburne University of Technology (in Australia) and a Diploma in Astronomy from University College London. Mona is also a Fellow of the Royal Astronomical Society and has a passion for sharing her knowledge with all interested persons. She adopts the principle that whether absolute beginners or old hands, we all have something to teach each other.

Mona explained that Caroline Herschel almost lived the stunted life of a domestic menial with undiscovered talents but this was averted by the intervention of her brother William. Caroline eventually became a highly distinguished astronomer who was sponsored by the King of England. In fact, historian Michael Hoskin remarked that both William and Caroline formed the most extraordinary partnership Astronomy has ever known.

The story starts in the middle of the 18th Century in Hanover (now Northern Germany) where their father, a military bandsman name Isaac Herschel was guiding his sons into a career as professional musicians while his wife was preparing the girls, including Caroline, for household help with the very minimum amount of secular education.

The Seven Years’ War broke out and resulted in the English and Hanoverian forces being defeated by the French. With some effort, Isaac got his two elder sons across the border to England. After the war, the eldest son returned to Hanover leaving William in England. When Caroline was 17 years old, her father died and it seemed like she was destined to spend an eternity as a household servant.

William’s younger brother Alexander joined him in England and they were both living in Bath and worked as professional musicians. William eventually journeyed to Hanover and struck an agreement with his mother – he agreed to pay for a servant to replace Caroline so that she could be allowed to move to Bath and train as a singer. This opened up a whole new world for Caroline. They initially lived at 7 New King Street in Bath and Mona showed us some pictures of the street as it exists today and jokingly questioned if the Herschel’s would recognize it today with all the modern cars and paved streets.

William used the time at breakfast to start teaching Caroline arithmetic and she carried on her training in English and music during the rest of the day. This continued for much of their time in Bath but as the time went on, William’s interests and involvement in Astronomy started to dominate his time and his devoted sister also picked up an interest in the subject.

Caroline helped William in polishing mirrors which were used to build William’s telescopes. He was interested in understanding, “the construction of the heavens”, and wanted to ensure that he had the best equipment he could afford at the time. On 13th March 1791, William’s observations led to the discovery of a previously unknown planet within our Solar System and he became an international celebrity. The planet was initially named after King George III and was called Georgium Sidus, or George’s Star but that name did not hold favour with the Americans and French so it was later named Uranus after the Roman sky god and father of Saturn. The site of the discovery, 19 New King Street, Bath, is now home to the Herschel Museum.

Soon after, the Herschels moved to Datchet which is closer to Windsor. Mona explained that the move from Bath to Datchet was quite good for William but Caroline was not really pleased with it as she realised that she was heading more towards astronomy and away from being a musician. However, by the end of the first year, Caroline took a keen interest in observing the night sky and discovered a cluster of stars which is now known as NGC 2360, Caroline’s Cluster.

In 1783, Caroline went on to discover another seven star clusters and even corrected some of the positioning of Messier objects. She eventually went on to discover genuine nebulae, star clusters and galaxies.

William then set up a new 20-ft reflector telescope and joined his sister in doing a full sky survey using Flamsteed’s Star Atlas. Mona showed us Caroline’s copy of this atlas which contained bits of candle wax, ink smudges and small annotations left by all the Herschels who used it. The book is now in the library of the RAS in Burlington House.

Mona continued to explain that William was still on his quest to understand the structure of the universe and he convinced King George III to finance a 40-foot-long telescope with a mirror 4 feet in diameter. They now moved to Observatory House, Slough where the great telescope was built over a period of two years. Of note, Caroline was now being paid by the king as William’s assistant, and thus became the first salaried woman astronomer in England. During the first summer in Slough, Caroline discovered her first comet by doing observations on her own and became recognized by astronomers, royalty, nobility and the general public.

At the age of 50, William got married to Mary Pitt and later had a son, John Herschel. Caroline went on to discover another seven comets and together with William, made some updates to Flamsteed’s star atlas including the introduction of an index, correcting errors and including several hundred missing stars.

After a period of deteriorating health, William passed away in 1822 leaving Caroline so distraught that she could not stay in England without William. At the age of 72, Caroline returned to Hanover and spent the rest of her time there.

There was one last mission which had to be done in order to complete William’s work. With Caroline’s help, it was John who took up the mantle and embarked on a journey for five years in South Africa to catalogue the southern hemisphere. Mona commented that when the work was finished, John wrote to his aunt to tell her that he was sending a copy of the published catalogue, he said that when it arrived “you will then have in your hands the completion of my father’s work”. Caroline lived to be almost 98 years and received numerous awards and recognition for the work, passion and dedication to astronomy.

Mona ended her wonderful talk by saying that William was able to accomplish so much because he had a partner such as Caroline, a brilliant woman and a perfect assistant. Mona further remarked that “their story goes on. Caroline turned her eyes to the stars and William broke through the barrier of the heavens. The story of their extraordinary partnership will go on until people can no longer be inspired by what they did and the legacy they left us”.

Many thanks to Mona for a talk which was well researched, well presented and full of passion.