1. The image to this date, cannot be explained by science.
2. The image shows no sign of deterioration after 450 years! The tilma or cloak of Juan Diego on which the image of Our Lady has been imprinted, is a coarse fabric made from the threads of the maguey cactus. This fiber disintegrates within 20-60 years!
3. There is no under-sketch, no sizing and no protective over-varnish on the image.
4. Microscopic examination revealed that there were no brush strokes.
5. The image seems to increase in size and change colors due to an unknown property of the surface and substance of which it is made.
6. According to Kodak of Mexico, the image is smooth and feels like a modern-day photograph. (It was produced 300 years before the invention of photography.)
7. The image has consistently defied exact reproduction, whether by brush or camera.
8. Several images can be seen reflected in the eyes of the Virgin. It is believed to be the images of Juan Diego, Bishop Juan de Zummaraga, Juan Gonzales, the interpreter and others.
9. The distortion and place of the images are identical to what is produced in the normal eye which is impossible to obtain on a flat surface.
10. The stars on Our Lady's Mantle coincide with the constellation in the sky on December 12, 1531. All who have scientifically examined the image of Our Lady over the centuries confess that its properties are absolutely unique and so inexplicable in human terms that the image can only be supernatural!
Supernatural doesn't sit well with the atheists. Maybe that's why God throws mankind a loop every once in a while (smile).
The scientific facts about the image of our Lady of Guadalupe on St. Juan Diego’s tilma cause many to claim that Glaudalupe is the greatest miracle of modern times.
There is also lots of information in the links above.
Thanks, A.A. for your input. The scientific viewpoint here is ssooooooooo powerful here.