Impressionism was born on November 13th, 1872, at 7:35 AM. That’s the result of calculations done by Texas State University astrophysicist Donald Olson on the work by Claude Monet that gave the movement its name. Monet called the painting, the harbour of Le Havre as seen through his hotel window, Impression, soleil levant (Impression, Sunrise) because it captured a fleeting moment and thus couldn’t really be called a view. He came up with the title a year and a half after he painted the scene when it went on public display April 15th, 1874, at the first exhibition of works that would within days become known as Impressionist at the Paris studio of the photographer Nadar. It had to have a title for the exhibition catalogue.

Thirty artists, among them Renoir, Pissarro, Cézanne, Degas, Sisley and Boudin, put their work on display at Nadar’s studio. All of them had been soundly and repeatedly rejected by the Académie des Beaux-Arts who insisted on traditional realism with invisible brushstrokes and muted colors for their prestigious Salon de Paris art shows. By order of Napoleon III (who was bowing to public clamor, not indulging a personal preference), they had gotten a chance to show their works in the Salon des Refusés, the Salon of the Refused, in 1863, but even though the Refusés saw far more traffic than the jury-selected works in the Salon de Paris, future petitions requesting new Refusés shows were, well, refused.

Finally the denied artists founded an anonymous collective and arranged for an independent show. They rented Nadar’s old studio (he had just moved to new digs) on the first floor (European first floor, that is, the storey above the ground floor shops) of a building at 35 Boulevard des Capucines and put 163 of their works on display two weeks before that year’s Salon de Paris opened.

Ten days later, on April 25th, 1874, the exhibition was reviewed by artist, playwright, journalist and critic Louis Leroy in the satirical newspaper Le Charivari. Entitled Exhibition of the Impressionists, the review used Monet’s term for his landscape of Le Havre to deride the weirdly blurry, poorly drawn, sloppy “palette-scrapings … on a dirty canvas” that so obnoxiously rejected the traditional forms of the great masters.

Leroy’s use of Monet’s term stuck, and the movement became known as Impressionism. As for the canvas that launched the label, Impression, soleil levant was purchased in May of 1874 by collector Ernest Hoschedés. He sold it four years later to Dr. George Bellio for a quarter of what he had paid. Bellio left it his daughter Victorine. On September 1st, 1939, the day Germany invaded Poland, Victorine transferred the work to the Musée Marmottan in Paris, which at that time had no Impressionist paintings in its collection, due to “risk of war.” Within days it was evacuated to the Château de Chambord along with the Mona Lisa, Venus de Milo and other masterpieces from the Louvre.

In May of 1940, with German forces advancing inexorably into France, Victorine donated the painting to the museum. Impression, soleil levant remained in hiding in Chambord for the duration of the war. For nearly two decades after the donation, the painting appeared in the museum’s inventories as Impression, soleil couchant (Impression, Sunset) and even though Monet had dated it 72 next to his signature, not much was known about him that year and there was dispute about whether he was actually in Le Havre in 1873.

The museum, now the Musée Marmottan Monet, to celebrate its 80th anniversary and the 140th anniversary of the seminal exhibition of the painting that named one of art’s most influential and revolutionary movements, enlisted the aid of Donald Olson to answer some of the questions about Monet’s piece.

He has pinpointed a particular third-floor bedroom with a balcony in the Hotel d’Amirauté au Havre, at 45 Grand Quai. Monet would have looked across the outer harbour, facing towards the Quai Courbe, to the southeast.

[…] Olson demonstrates that because of the sun’s position towards the east it must have been rising. He also calculated that the sun rises in the position shown in the Monet painting twice each year, in mid-November and late-January. The sun is depicted two to three degrees above the horizon, which corresponds to 20 to 30 minutes after sunrise.

Olson then looked at the level of the sea, since large ships can only pass in or out of the outer harbour for three to four hours at high tide. Taking the sun’s position, plus the high tide, this narrowed down the possibilities to 19 dates in 1872-73.

The next stage of the puzzle was to examine weather reports—to exclude days when cloud would have obscured the sun and to include only days when there was fog. This further winnowed the dates to six: 21 and 22 January 1872, 13 and 15 November 1872 and 25 and 26 January 1873.

Olson then focussed on the plumes of smoke on the left side of the painting, which rise into the sky towards the right. Meteorological reports suggest that this wind direction would have occurred on only two of the six dates, on 13 November 1872 and 25 January 1873.

The final factor is the research of Géraldine Lefebre, a curator at the Musée d’Art Moderne André Malraux in Le Havre. She is convinced that the year “72” inscribed by Monet on the painting is correct, since what we know of Monet’s movements makes it very unlikely he was there the following January. This means that Impression, Soleil Levant depicts the view in La Havre on 13 November 1872, at 7.35am.

Impression, soleil levant will be the centerpiece of an exhibit that runs from September 18th, 2014, to January 18th, 2015. It will join another 24 works by Monet, including a night view of the harbour of Le Havre painted from the same hotel room, plus works by Delacroix, Turner, Renoir and Pissarro, among others, loaned from top museums and private collections around the world.