Atlas of Light
Atlas of Light
Whether it is direct or reflected, emitted by a point or an extended source,
light guides the steps of the photographer, directs the gaze of the astronomer.
It is to simulate then to observe the effects of this natural or artificial light,
of its diurnal, seasonal or secular variations upon our environment,
on our way of thinking, that this new cartographic adventure invites you ...
Introduction
This cartographic experience is based on various numerical simulations of the Earth and Sky - in two, three or even five dimensions:
- 2D simulations represent the sky visible to the naked eye from Earth. As their distance from Earth is visually inaccessible to us, all celestial objects appear to be spread out on the surface of a sphere centered on Earth - the so-called celestial vault.
- 3D simulations allow us to represent the light variations at the Earth's surface - according to the hours of the day or the seasons of the year, to show our Earth among the other planets in our Solar System, our Solar System within our host galaxy, the Milky Way, and so on.
- 5D simulations make it possible to reconstruct the celestial vault overhanging a given terrestrial landscape in any epoch, past, present or future. In this context, the Earth's surface is endowed with three dimensions representing topography on a planetary scale, the celestial vault constitutes the fourth dimension, and time the fifth dimension of this unique Sky/Earth interface.
These simulations were carried out using various OpenSource softwares distributed under the Apache 2.0 (NASA/ESA WebWorldWind) or OpenSource BSD (OpenLayers, d3-celestial) or GNU General Public (Celestia) license, satellite images and altimetry data made available by space agencies (NASA, ESA, JAXA).
This 3D view of the Earth illuminated by the Sun, surrounded by the constellation of Orion and the star Sirius, is the result of numerical simulations combining satellite images of the Earth and algorithms of positioning of the objects (Earth, Sun, stars) on the celestial vault. It simulates a view acquired on March 21, 2022 at a distance of 50 000 km (*). Although plunged into darkness, the artificial lighting draws the contours of the American continent.
(*) This simulation was performed using the WebWorldWind interface developed by the NASA/ESA consortium and distributed under the Apache 2.0 license.