RALEIGH — Scientists from Texas State University have pinpointed not just the day but the precise minute depicted in one of the finest paintings by the Impressionist master Claude Monet a painting that just happens to hang in the N.C. Museum of Art.
The moment caught in The Cliff, Étretat: Sunset, with its mercury-like reflections of sea and black cliffs in shadow, had long been known to have taken place on Frances rugged Normandy coast sometime in 1882 or 1883.
For many works of art in the museum, knowing the exact day they were created let alone the minute depicted would be of little or no consequence.
Not so with the Monet. It adds a particular resonance because capturing a specific scene, and the quality of light at a particular instant, was at the heart of the Impressionist movement and its rejection of the academic painting, even landscapes, that was so often done in studios.
Many people just think of Impressionist paintings as pretty, said Perry Hurt, an associate conservator at the museum. But for the Impressionists, it was this recording of the moment, of the site, of something real and immediate, rather than something artificial.
The methods involved are described in an article in the February issue of Sky & Telescope magazine.
It wasnt rocket science, but it was astronomy. And history. And hiking.
The exact moment
The researchers, led by astronomer and physics professor Donald Olson and including a graduate student from UNC-Chapel Hill, traveled to Normandy in 2012. They brought along high-tech and low-tech instruments, including a sextant and a laser rangefinder. They also brought several postcard depictions of a dozen or so paintings that Monet made along the rugged coastline there.
They used the cards to determine the precise location where Monet worked on a whole series of paintings along the Normandy coast. Their main focus was on one painting because, unlike the others, it had a crucial detail: a distinct disc for the sun.
You see a glow in many, where the sun has set, but you just dont know where it is, Olson said.
That allowed the researchers, once they had the location, to determine how high above the horizon the sun was in the painting, and where it was in relation to an arch in the cliff and a rock spire shown in the painting. The arch and spire were several hundred yards apart, so the scientists were able to line them up precisely to help determine Monets vantage point.
They took that information, and the position of the moon and stars during their visit, and punched it into a computer program designed for such questions. That narrowed down the date shown in the painting to sometime between Feb. 3 and Feb. 7, 1883.
Then they used letters Monet wrote during that period, and historical tide and weather information, to pin it down precisely. In letters home from the coast, Monet had written that on Feb. 3 he was working on another beach and complained that he had spent the entire next day entertaining his brother.
On Feb. 6, the tides which Monet was known to pay close attention to for reasons of both art and his own safety were wrong for the painting. On Feb. 7, the weather was stormy. But Feb. 5, the weather was fine, and the tide matched the time of day he depicted.
To get the precise time of day, the scientists used the height of the rock spire which they measured with four methods that all ended with results no more than a meter apart along with the angle of the sun above the horizon as shown from the place they determined that Monet had used to paint.
The full answer: 4:53 p.m. on Feb. 5, 1883.
Alongside the painting in the N.C. Museum of Art hangs a similar-sized Monet, Waves at the Manneport, which features another stone arch just a few hundred yards away from that in Étretat. The brush strokes are broader, and there are other style differences that allow experts to deduce that probably most of it was painted on site in just a couple of days. That being his modus operandi, its also likely that Monet painted The Cliff, Étretat, Sunset in similar fashion, most of it rapidly and on location, Hurt said.
But Manneport has no sun, so its moment will likely never be known.
Revealing history with the sky
The methods were the norm for an honors class that Olson teaches periodically, called Astronomy in Art, History and Literature.
He has just published a book, Celestial Sleuth: Using Astronomy to Solve Mysteries in Art, History and Literature, that details more than 30 such cases he investigated. Some involve historical questions, including the logic behind the timing of the Pearl Harbor attacks, and the quality of the moonlight that led to the accidental shooting of Confederate Gen. Stonewall Jackson by his own troops. It also details projects exploring other paintings and works of literature.
In this case, Olsons team learned more about Monet than just where and when he painted. They also found that he took extraordinary risks to get just the right angle.
One of the biggest threats he faced was the tides, which are famous in the area for huge rises and drops, up to 28 feet. The beaches can disappear in minutes, and there are warning signs everywhere, in multiple languages.
Eva Pope, who had studied under Olson at Texas State but was a graduate student in physics at UNC-CH when the group traveled to France, is a hiker and avid cave explorer. She said she was daunted by the crumbling cliffs, extreme tides and treacherous footing that Monet braved at the waters edge. Slimy seaweed on sharp rocks gave those beaches some of the worst footing she has ever experienced, she said.
I had trouble getting out there while just protecting my little point-and-shoot camera, Pope said. I cant imagine walking out there with an easel and paint and staying long enough to get something done.
In one letter, Olson said, Monet wrote about being caught on a beach when he misjudged the tide, thinking it was going out. A huge wave surprised him, washing away his easel, paints and brushes, and smacked his palette against his face, leaving his beard a rainbow. It came within a whisker of washing him out to sea, he wrote.
Thats the kind of detail that drives Olsons imagination.
It just enriches our lives to look at great art, to study important historical events and great literature, Olson said.