Artificial satellites orbiting the Earth. Data provided by Space Track in TLE format, propagated to space-time coordinates using satellite-js.
Each satellite is projected at the location on Earth where it’s directly at the zenith. The area of each circle is inversely proportional to the satellite’s altitude from the surface, so closer (and faster orbiting) satellites will exhibit a larger radius.
The Voronoi cells are computed iteratively according to the satellite layers in view, using d3-geo-voronoi. d3-geo-zoom is used to handle the globe zoom/pan interaction.
See also Earth Satellites and Geostationary Satellites.