This is a novel that I found deeply satisfying while at the same time profoundly annoying on numerous levels. While reading it I was initially alienated by its pretentiousness (having the narrative in the present tense and its past in the pluperfect isn't clever or arty, just self-indulgent) and came very close to throwing it at the wall before I reached page 50. However, my fascination with Caroline and William Herschel as science-historical figures kept me going, and I'm overall glad that it did.
The bones of the story are what we know from history. The Hanoverian genius William Herschel came to England as a young man and embarked upon two successful careers there, as a composer and as an astronomer. (He was no mean composer, by the way. If interested, you should be able to find some of his works on YouTube.) After a while he brought over to England his younger (by 12 years) sister Caroline, who became not just his housekeeper and Admin Officer but also his devoted companion at the telescope. In due course Caroline became an astronomer of distinction in her own right, discovering a passel of comets, making radical and important improvements to John Flamsteed's star catalogue, and more. While she'll always be overshadowed by her elder brother, who discovered the planet Uranus (he thought initially it was a comet, and then wanted to call it Georgium Sidus), there's no doubt that, had she been born in a different age when women weren't expected to be subservient, she'd be regarded as at least his equal and might well have eclipsed him.
That's the history.
In The Stargazer's Sister Carrie Brown sets out to tell the human story -- to turn the historical figure of "Lina" Herschel into someone we can love. In this she very much succeeds. After a while I became inured to the godawful jumble of tenses noted above and found myself totally immersed in Caroline and her world -- whenever I put the book down I had to make a conscious effort to snap myself out of its ambience. I was a fan of Caroline Herschel before; now I'm even more so. (If anyone ever makes the movie, could it possibly star Sarah Polley?)
And yet . . .
Brown admits at the end that she made a few adjustments to the historical record for the purposes of, y'know, Art.
On balance, I wish she hadn't. Some of her artifices are fine -- William was present in Hanover with the family to watch an eclipse when in reality he wasn't, in England the Herschels had a lifelong servant and friend called Stanley whom Brown invented out of whole cloth -- but others are actually pretty naff. Examples:
Later in the novel William marries a widow, Mary Pitt, and Caroline, who has devoted much of her life to her adored big bro, has a few years of miffedness about this. She and Mary make up, though, and, as William nears death, Caroline rues that the couple never had children: "How William would have loved to have had a son, sob, bwah." (That may not be an exact quote but it encapsulates the faux-pathos.) In reality, the couple had a son, John, who went on to become a major astronomer in his own right. More than that, because he based so much of his own work on Caroline's, and told her that this was the case, he was an important influence on her later life -- he made it clear she was not the useless maiden great-aunt her brother Dietrich told her she was after she moved, following William's death, back from England to Hanover.
Except, in the novel, that's not what happened. Instead of moving from England to Hanover after William's death, she moved for a decade or so to Lisbon, where she was taken in by and became the lover of fabulously wealthy amateur astronomer Dr Silva. Silva is another of the author's invented characters, and the relationship never happened -- any more than did that between Caroline and the unfortunately syphilitic benefactor of the Herschels and putative husband, the nonexistent Sir Henry Spencer.
I have absolutely no objection to historical/biographical novelists inventing stuff in order to fill in the gaps, so to speak. Had Brown correctly depicted Caroline moving straight from England to Hanover and there having the love of her life with some or other Dr Silva, I'd have thought this was entirely within any novelist's right -- just as I do Brown's invention of Stanley as the epitome of all manner of faithful servants the Herschels must have had. Yet to invent a whole, decade-long episode of the subject's life that the historical record quite clearly indicates never occurred? That, I think, goes too far.
Another major problem I had with the novel was its dearth (not total lack) of "scienciness": oh, ya, discovered a new planet, ya, right (Brown never even discusses the debate over the planet's name). There are cosmological ideas thrown in that seem centuries before their time, as if William were precognitive: nebulae as external galaxies, the possibility of black holes. If William indeed had these insights, I really wanted to hear more about them!
(And shall. Michael D. Lemonick's The Georgian Star has just moved closer to the top of my pile.)
Overall, then, if you want to approach this book as an often extremely moving novel about love and the places it can lead to, you're likely to be rewarded. If you're seeking a biographical novel that remotely represents reality, then you're likely to be as annoyed as I often was.