Forensic astronomers have been able to pinpoint the exact day on which van Gogh's Moonrise was painted.
Credit: Stichting Kroller/Muller Museum; AFP
Myths and classical literature often refer to signs and omens in the sky. "These late eclipses in the Sun and Moon portend no good to us," says a character in Shakespeare's King Lear.
Modern readers tend to presume that these references are mere window dressing: like murder on a dark and stormy night or thunder in a B-grade horror movie. But recently, scientists have discovered that they can be used to resolve long-standing historical debates.
Scholars, for example, have never been sure when Shakespeare wrote King Lear. Estimates ranged from about 1604 to 1606. But in 2001, astronomer David Levy (co-discoverer of comet Shoemaker-Levy 9, which crashed into Jupiter in 1994) began a doctoral thesis on "The Sky in Early Modern Literature". In 1605, he determined, Londoners were witness to both a lunar eclipse and a near-total solar eclipse, one in late September and the other in October. Odds are that Shakespeare had these in mind when he wrote his play. If so, he was still working on it in late 1605.
Donald Olson, a physics professor at Texas State University in San Marcos, U.S., has used similar techniques to help art historians pin down details of famous paintings. In 2000, for example, he found the location at which Vincent van Gogh created one of his last paintings, The White House at Night.
Knowing that van Gogh painted it in mid-June, and the direction in which the house faced, Olson was able to determine that a bright star in the painting was mostly likely the planet Venus, which would have been prominent at the time.
Two years later, Olson used a similar process with another van Gogh painting, Moonrise. That painting depicts the full Moon rising behind an overhanging cliff in southern France. Historians knew the work was made sometime in 1889, and haystacks in the foreground indicate that the time of year is somewhere around harvest season.
Olson's team hunted down the location and, with a bit of astronomical detective work, determined that there was only one date on which the Moon rose in the right place: 13 July 1889. Since van Gogh once said he never worked from memory and always painted what he saw, this was probably the date on which he started painting Moonrise.
Scientists call this emerging field of research forensic astronomy. It's becoming popular, says Geza Gyuk of Adler Planetarium in Chicago, Illinois, because of the ready availability of off-the-shelf astronomical software such as Starry Night and RedShift. It means that anyone with a computer can see what the sky looked like from anywhere in the world, at any date in history. The programs are not only remarkably accurate, but they're also easy to use. "It's the work of an afternoon now to sort through all the autumn moonrises from a particular location on Earth during a particular span of years," says Gyuk.
