In 2026, the bicentenary of photography, the Hauts-de-Seine Department is dedicating an open-air exhibition to the art form at Parc de Sceaux, which will run until December. Among the selected images is a remarkable photograph taken at the Paris Observatory in Meudon : the silhouette of a Boeing 747 flying from Buenos Aires to Frankfurt – identified thanks to the regional air traffic control centre – passing in front of the Sun.
On 12 September 1992, the heliograph captured this transit by chance. Fitted with a Lyot filter, the instrument was photographing the Sun in the Hα line, taking five successive exposures at different wavelengths : at the centre of the line, then in its wings at ±0.5 and ±1 Å, in order to study solar activity. The three images shown correspond to the centre of the line and ±0.5 Å. A rare instance of an aeroplane passing in front of the Sun, immortalised amongst more than a century of solar observations carried out at Meudon, forming a database that is unique in the world.
