Equation of time is an artistic and scientific experiment initiated in 2018 at the Paris Observatory by photographer Raphaël Dallaporta. Conducted jointly with researchers from the Syrte (Système de Références Temps-Espaces) of Paris Observatory, the experiment “Equation of Time” aims to verify the differences between the true solar day, indicated by sundials, and mean solar time, indicated by clocks. While the meridian of true solar time is a straight line, the meridian of mean time has the shape of an elongated figure eight.
Every day for a year, at the exact same time, Raphaël Dallaporta took a picture of the Sun entering the Cassini room, which was built in 1671. The accumulation over the year revealsthe curvein 8 of the equation of time ∞ represented by the image of the Sun on the Earth.
about the equation of time
The equation of time is a notion that reflects the inequalities of solar time. The notion of “mean solar time” corresponds to an ideal, fictitious time, where the sun returns in the same direction after 24 hours. Every day when the Sun is visible, the Sun passes at the meridian of the observatory, in this Cassini room. We can see this spot of light that cuts the Paris meridian at solar noon.
about the book
Each of the first 365 pages of this book is centered on the position of the image of the Sun during its passage at the local mean noon in the Cassini room of Paris Observatory (48°50’11”N – 02°20’14”E). The pictures were taken by Raphaël Dallaporta as close as possible to the eyecup located at 9.933 m south of the meridian. From this point of view, the image of the Sun appears circular, the perspective reducing the variations of its elliptical projection during the year. In the following pages, astronomer and science historian Denis Savoie explains the principles of the equation of time, based on the plot of the figure-eight curve when the Earth’s revolution around the Sun at the end of a year is completed.
Conceived as a playful flip book by the Kummer & Herrman studio, the reader discovers the figure-eight curve that forms over the pages.
In the afterword, the astronomer Denis Savoie explains the principles of the equation of time, based on the curve of the figure of eight, the revolution of the Earth around the Sun after one year.
The book was published as part of the Prix Niépce Gens d’Images, of which The Eyes Publishing has been a patron since 2019, in collaboration with the Picto Foundation.
about the author
Raphaël Dallaporta, born in 1980, has developed a work that has been critically acclaimed for the rigor of its shooting protocols, its documentary conviction and the relevance of its installations in which unusual connections are established between history, science, art and technology. Each of his projects, seeking to make visible phenomena, objects or territories, respectively hidden, taboo or inaccessible, are finalized by a monographic publication. Raphaël Dallaporta bases his approach on a scientific approach in order to question first of all the empathy generated by social subjects, and to play with the often varied statuses of a photographic image. All his work follows a movement that extracts photography from its documentary condition to summon a symbolic vision.
He is the winner of the ICP Infinity Award 2010 in NewYork and the Paul Huf Award 2011 of the Foam in Amsterdam. After having been a resident at the Académie de France in Rome – Villa Medici in 2014-2015, he realized the project Chauvet-Pont d’Arc, l’inappropriable, published in 2016 by Xavier Barral and exhibited in Kyoto, Japan and at the Centquatre-Paris.
Raphaël Dallaporta is represented by the Jean-Kenta Gauthier gallery, which was supposed before the lockdown to organize an exhibition the project and the book from November 21 to December 19, 2020. New dates to be communicated soon.
VIDEO INTERVIEW // Raphaël Dallaporta & Denis Savoie
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