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Space is full of cosmic mysteries waiting to be solved by star-gazers. Yet on Earth, astronomers can also help to shed light in a rather different field – art. “Celestial Sleuth” Professor Donald Olson of Texas State University applies the methods of “forensic astronomy” to solve some of the burning questions in the art scene. Olson’s latest case involved Dutch painter Johannes Vermeer’s masterpiece View of Delft (pictured above).
A prime example of Vermeer’s technically precise depiction of light and shadow, the cityscape of Delft has left historians and artists alike pondering the exact date and time of the scene on the canvas. Scholars had failed to agree on whether the painting depicted the morning or afternoon, or whether the sunlight was coming from the west or right overhead. This was a job for Olson and his own Mystery Incorporated crew, whose findings are published in the September 2020 issue of Sky and Telescope magazine.
“The students and I worked for about a year on this project,” Olson said in a statement. “We spent a lot of time studying the topography of the town, using maps from the 17th and 19th centuries and Google Earth.”
From their primary investigations, Olson and his team realized that from Vermeer’s north-facing viewpoint (the second floor of an inn overlooking the city) the lighting of the scene would be achieved from a south-easterly source (i.e. the painting was of the morning). To improve the accuracy of their Google Earth measurements, the team then had to take their own mystery machine (plane) to Delft and see the scene for themselves.
A particular feature of interest was the octagonal tower of Nieuwe Kerk (New Church). Whilst some literature had suggested Vermeer had inflated its size, the researchers own examination revealed that Vermeer once again was spot on. This finding enabled the team to calculate the exact angle of the Sun in the painting using the shadows of the tower’s column.
An especially sensitive indicator of the Sun’s position is the narrow illuminated vertical column (red arrows), which appears for only a few minutes as the Sun moves across the sky. On the left is Vermeer's depiction, and on the right the tower on October 16, 2019. Mauritshuis, The Hague; Russell Doescher.
“That's our key. That's the sensitive indicator of where the sun has to be to do that, to just skim the one projection and illuminate the other,” Olson said. “The pattern of light and shadows was a sensitive indicator of the position of the sun.”
On the scent, the team took a closer look at the tower clock’s time. For years it had been interpreted as “just past seven o’clock,” but as minute hands were not added on tower clocks until the late 19th century, an alternative reading yielded a time closer to 8am.
Now for the year. As the tower’s bells were not installed until 1660, and the painting shows an empty belfry, Olson and the team knew the painting was conceived prior to this date. In fact, inputting the Sun’s angle and clock time into astronomical software, they narrowed down the date ranges to two possibilities: April 6-8 and September 3-4.
As with all good detective stories, there was one last obscure piece to this puzzle – the leafy trees. In Delft’s northern climate, the trees lay bare until the end of April, ruling out the spring date. Ultimately this closed the case – Vermeer’s View of Delft was likely inspired by the scene observed on or near September 3, 1659 (or an earlier year) at 8am local mean time.
“Vermeer is known to have worked slowly. Completing all the details on the large canvas of his masterpiece may have taken weeks, months or even years,” Olson said. “His remarkably accurate depiction of the distinctive and fleeting pattern of light and shadows on the Nieuwe Kerk suggests that at least this detail was inspired by direct observation of the sunlit tower rising above the wall and roofs of Delft.”
