you clicked on the centerpiece of The Poster:

You can download this beautiful poster in full 6000x6000 pixel size (20" by 20" if printed 300dpi, and using 26MB), or a smaller 1000x1000 pixel (376KB) version. Alternatively, here is a color-postscript (8.4MB) directly for the printer.

The mosaic: Ptolemaic System, ca. 1661

Mexican Talavera tile mosaic by: Talavera de la Luz, Puebla, Mexico.