Discoverers of the Universe: William and Caroline Herschel

What a charming book!

Before I explain why I enjoyed reading this book I should mention that I am a mathematician but also an amateur astronomer (emphasis on amateur). The astronomical and biographical aspects of the book are fantastic and the amateur astronomer in me was overjoyed to read about the Herschels’ work. But as a mathematician I was left disappointed that the author did not go any deeper (or at all, really) into the surely amazing mathematics that the Herschels applied in their astronomical and engineering work. Obviously, this book was not written with mathematicians in mind, but aims at a general audience instead. Those readers with an interest in astronomy and/or history of science will surely find it as enjoyable as I did.

Discoverers of the Universe is a wonderful account of the lives and astonishing achievements of three family members: William and Caroline Herschel (brother and sister), and to a lesser degree William’s son, John. William and Caroline were born in Hanover, Germany, in 1736 and 1750, respectively. They moved to England in 1772, and settled first in Bath and later relocated to Slough, near King George’s court at Windsor. They moved to England as (talented) musicians but, following William’s passion for astronomy, eventually became one of history’s most successful scientific duos. What began as William’s hobby of watching the night sky became an obsession. William designed some of the most elegant, useful, and powerful telescopes of the time to be able to see further and with better resolution than anyone had ever had. His obsession for better optics, more light-capturing power, and increased magnification led him to build larger and larger telescopes — a race that culminated in a mammoth 40-foot reflector telescope. His feats in structural engineering of telescope mounts, in refining methods to build and polish mirrors, and in perfecting Newton’s reflector telescopes and optics, allowed him (with the invaluable help of Caroline as amanuensis) to achieve perpetual glory in the annals of astronomy.

The list of William’s accomplishments is extraordinary. His career began with a bang when he discovered Uranus as an amateur backyard astronomer. William was the first person in recorded history to discover a planet, and with this discovery, the scale of the solar system doubled overnight. Uranus, or the “Georgian star” as he would call it in honor of King George, earned him a position as the “King’s astronomer at Windsor” (not to be confused with the more prestigious Astronomer Royal — a position that was not granted to him for political reasons). William and Caroline created large lists of double stars and, most importantly, a catalogue of more than 2500 nebulae visible from the northern hemisphere that is still in use today. After William’s death, John would complete his father and aunt’s job by travelling to the southern hemisphere and listing an additional 1700 nebulae, 2100 double stars and 70000 stars.

When Caroline Herschel was not helping his brother transcribe his observations, she was also sweeping the night sky with a smaller telescope that William made for her. She earned her own reputation by discovering 9 comets. In recognition of her own achievements and her invaluable help to William, King George assigned her a stipend and she became the first salaried woman astronomer in history. Later on, after William had passed away, she helped her nephew John by reorganizing the catalogue of stars and nebulae in a much more sensible manner that was much more useful for the astronomical community at large. This was no small task: she started in 1799 and it took her until 1818 to finish the job. The newly organized catalogue earned her the Gold medal from the Astronomical Society of London, the Gold medal in science from the King of Prussia, and eventually an honorary membership in the Royal Astronomical Society.

Perhaps I should admit that I am not a frequent reader of biographies but Discoverers of the Universe reads almost like a novel, so the book was thoroughly enjoyable. In contrast to Sir Isaac Newton’s difficult personality, the author writes that “the Herschels are lovely people, and it has been a privilege to become an invisible member of their family. I hope that when you finish the book, you will feel the same.” And I sure did. Through historical records, interesting facts, and amusing anecdotes (e.g., when William met Napoleon), the author paints a very vivid picture of their lives and personalities, their struggles and achievements, their hardships and their successes. This episode in the history of science is fantastic, but the human factor in the story is what makes it a very enjoyable book.

Astronomers, amateur or otherwise, will be delighted to read about the Herschels’ accomplishments (e.g., how William coined the term “asteroid”; how Ceres was discovered; the quest to prove or disprove the existence of “true nebulosity”) but I believe other readers without an astronomy background will find the book equally appealing. The treatment is very light in terms of astronomy or astrophysics, so anyone with a basic science background should be able to enjoy and appreciate the importance of the discoveries, aided by the author’s concise and clear explanations.

As I mentioned at the beginning of this review, I was disappointed on the mathematical side. For instance, I wish the author had included (perhaps as an appendix) a little background on the mathematics that William Herschel must have used to create the nearly perfect parabolic shape of his mirrors. The only instance when numbers make an appearance in the book is during the discussion of Bode’s law that would be used to predict the location of Ceres. Sadly, the law itself is mere numerology, not mathematics. (Bode’s law, to this day, has no solid explanation.) There was another opportunity lost to discuss brilliant mathematics in the treatment of how a young Gauss, using only fragmentary observations by Piazzi, was able to calculate Ceres’ orbit. William later found Ceres with his telescopes using Gauss’s coordinates. I completely understand why the author would not want to include some mathematics that would put off a large part of his intended audience, but as a mathematician I can only dream that one day most readers will expect and demand (at least some) mathematical explanations in any history of science book.

Álvaro Lozano-Robledo is Assistant Professor of Mathematics and Acting Director of the Q Center at the University of Connecticut.