I mentioned yesterday that the average cloud cover for New England is about 60 percent. Although the percentage varies widely depending on location and season, 60 percent is about average for the entire globe.
But what if the number were 100 percent? How would the intellectual history of humans have been different on a cloud-covered planet? No part of the natural environment is so clearly marked by regular periodic phenomena as the heavens. Anthropologist Alexander Marshack argued that certain regular markings on bone artifacts of Ice Age humans record the changing phases of the moon, and that these are the earliest examples of symbolic notation. Historians of science Giorgio de Santillana and Hertha von Dechend contend (in a book called Hamlet's Mill) that all of the great myths of the world have their origin in the regular behavior of celestial bodies. Other commentators have stressed the connection between the heavens and the development of scientific thought.
As Jacob Bronowski pointed out, the stars might seem improbable objects to have aroused such curiosity. The human body is closer at hand and a more obvious candidate for systematic investigation. But astronomy advanced as a science before medicine, and early medicine turned to the stars for signs and omens. The reason is clear: The regular motions of the heavens lent themselves to mathematical description. Behind the apparent chaos of terrestrial experience, the stars proclaim the rule of law.
On a cloud-shrouded Earth the rise of the human species to civilization would almost certainly have been delayed. Delayed, but not forestalled forever. The survival value of science and technology is such that sooner or later the inhabitants of the White Planet would have developed vehicles to lift themselves above the clouds. We can imagine their first view of the universe beyond the clouds -- the beckoning stars, the Milky Way, the luminous orb of the Sun, the changing Moon, planets and comets, solar and lunar eclipses -- celestial rhythms at last laid bare, the rule of mathematical law, so laboriously learned in the terrestrial environment, in the heavens made crystal clear.