Down to Earth

I recently picked up a book called The Passion of the Western Mind by Richard Tarnas. It was written about fifteen years ago. It's about how modern thought developed from its ancient Greek and Christian origins. I'm only half way through it but already I'm struck by his emphasis on the role of astronomy in the development of Western science.

Nowadays most people live in cities so we don't get to appreciate the majesty of a starlit night sky, with the milky way arching high overhead and millions of stars glittering like diamonds. Nowadays you can only see that kind of sky if you're out in the wilderness. Thousands of years ago there wasn't as much competition from artificial lights so everybody could see it.

Down here on Earth, things change very quickly. Things die and decay, there's dirt and mud, and the weather is never the same from one day to the next. But they don't call the starry sky, ”the heavens” for nothing. To the ancients, the stars appeared changeless and eternal. Each star, night after night, never changing it's place in relation to the other stars. Except, there were this handful of stars, that over the course of weeks and months moved against the backdrop of fixed stars. These wandering stars, ie., “planets”, seemed to come and go at regular intervals. Because the planets messed up the perfect order and symmetry that otherwise appeared to exist in the heavens, the ancient Greeks from Pythagoras to Plato to Ptolemy made it a priority to understand how and why the planets moved.

Modern science was born from renaissance Europe's attempt to further the Greek understanding of how the planets moved, starting with Copernicus and continuing on with Galileo,Kepler, Newton, and Einstein.

By the late nineteen-sixties the United States had sent men to the moon and back. In 1972, on the seventeenth Apollo mission the first  picture of the Earth as a full hemisphere (the Earth equivalent of a full moon) was taken from the window of the spacecraft. This picture, which shows all of Africa, the Arabian Peninsula and a great swirl of clouds in the South Atlantic, could well be the most popular photograph in history. The orange and greens of the continents and the deep blue of the oceans, the great weather systems that change the face of the Earth from day to day, all captured on a single photograph. You can google it, people have posters of it. It's featured on book covers and in magazines. All the years that we've been looking up to the heavens and longing for their perfection are eclipsed, when we finally get to see what the planet we're standing on really looks like. How like a living thing the Earth is.

Now in 2007, almost forty years later, with the threat of global warming our scientific understanding must be focussed on Earth if we are to survive. How has the Earth kept it's temperature so close to constant up until now? How has the atmosphere contained just the right amount of oxygen for us to breathe? How can we lower carbon dioxide emissions and live on Earth in a way that does not compromise our ability to survive? These are some of the questions that science needs to answer.

The scientific enterprise has largely soved the problem of planetary motion that so vexed the Greeks, but in doing so it has led us back down to Earth rather than upwards towards the heavens.