Many have doubted her claim, instead postulating that she conceived the story from conversations she was having at the time, or from some other source.
Doubting Shelley's words was easy enough before the recent article by Donald Olson, an astronomy professor at Texas State University in San Marcos, which appeared recently in "Sky and Telescope" magazine. Now that they have proven a gibbous moon, bright and shiny, did indeed shine directly through her bedroom window at the time, doubting is a much more difficult thing.
This is hardly the first time astronomers have been able to prove an historical event by tracking the position of the stars in the sky. Unlike some other sciences, where the best that can be given is a 90% likelihood, astronomers can determine the exact position of the stars, moon and other celestial bodies, by retracing the position of the Earth from years long past.
Shelley first wrote of how she came to write Frankenstein in the preface of the book's 1831 edition, and critics immediately began questioning her story as simply a ruse to sell more books.
The story goes like this: Shelley was staying with her future husband, Percy Shelley, at the Villa Diodati in Switzerland in June of 1816. Also present were Lord Byron and friends Claire Clairmont and John Polidori. Byron challenged all of them to try their hand at writing a ghost story.
Shelley saw the "bright and shining moon" through her window that night and wrote the story while she was in what she called "a waking dream."
The closest account of Byron's challenge comes from Polidori's diary, in which he tells of the party gathering at the Villa Diodati for a philosophical discussion that ended "after the witching hour" of June 16, 1816. The next day he wrote that "the ghost-stores are begun by all but me."
But Olson said there was no record of the challenge itself from any sources other than Shelley's preface, and the assumption has always been made, though not proven, that the challenge and the writing took place early in the morning of June 16.
But he said that had never been confirmed until now.
"We verified when the moon would have shone on her window, which is when she first came up with the idea for the story we know as Frankenstein," Olson said.
Click here to read more about Olson's discovery at Reuters.