Shelley has long been doubted for her version of events that led to the writing of one of the most beloved Gothic tales in the English language: That she wrote it on a challenge one night in June 1816 during a "waking dream" as the moon shone through her window.
But Donald Olson, an astronomy professor at Texas State University in San Marcos, told Reuters on Monday that the night sky would argue that she was telling the truth.
"Some scholars are very skeptical, they even call her a liar," Olson said. "But we see no reason, either in the science or in the primary sources, to doubt Mary Shelley's account."
Olson has made a hobby out of using the sky to solve the mysteries of many of the world's most famous works of art and historical accounts.
His study of tides in the English Channel forced historians to change the accepted date of Julius Caesar's invasion of Britain in 55 BC, and he used astronomical tables to pinpoint where and when Vincent Van Gogh painted the famous painting alternately known as "Moonrise" and "Sunrise over Saint-Remy."
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.
The Villa Diodati still stands above Lake Geneva and the room where Shelley stayed is well known. Olson and his researchers made "extensive topographic measurements of the terrain" and investigated "weather records for June of 1816," described by Lord Byron and Polidori as unusually wet and rainy.
On that night, however, "we determined that a bright, gibbous moon would have cleared the hillside to shine right into Shelley's bedroom window just before 2 a.m. on June 16," Olson said.
He said that had there been no moonlight visible that morning, it would have indicated fabrication on her part.
"This indicates her famous "waking dream" that gave birth to Frankenstein's famous monster occurred between 2 a.m. and 3 a.m. on June 16," he said.
"Mary Shelley wrote about moonlight shining through her window, and now we have recreated that night," Olson said. "We see no reason to doubt her account, based on the astronomical data."
Olson's study appears in the October edition of "Sky and Telescope" magazine.
(Editing by Karen Brooks and Cynthia Johnston)