While the exhibition dedicated to Vincent Van Gogh at the Vittoriano in Rome is about to close after being extended for another two weeks by popular demand, a research carried out by the Italian CNR, the University of Perugia’s Department of Chemistry, the University of Antwerp’s Departments of Chemistry and Physics, the Delft University of Technology (TUDelft) and by the Esrf (European Synchrotron Radiation Facility) in Grenoble has discovered why the yellow color of the sunflowers painted by the great painter is turning brown.