Perhaps the greatest achievement of Alexandrian science is Aristarchus’ book, On the Sizes and Distances of the Sun and the Moon, a work of skillful observation and flawless logic that compares favorably with anything in modern science. Eratosthenes measured the size of the Earth with a combination of celestial and terrestrial observations. Latitude and longitude were invented. The equator, poles, polar circles, and tropics were deduced, although the only one of these places of which the Alexandrians had direct knowledge was the Tropic of Cancer, which passed through the town of Syene in the valley of the Nile, near the site of the present Aswan High Dam. It was in Alexandria, for example, that geography and astronomy were made mathematical sciences. Euclid, Apollonius, Archimedes, Eratosthenes, Aristarchus and many others worked or studied in Alexandria. In the 3rd and 2nd centuries B.C., Alexandria became the seat of a magnificent flowering of mathematical and scientific thought. They found a welcoming home in the Hellenistic city of Alexandria at the mouth of the Nile River in Egypt. The ideas sprang from Greek philosophy. Electric lights, air conditioning, and satellite navigation, like all other modern technologies, flowed like a river from this powerful new way of making sense of the world. So let the names of the tropics remain as they were 2,300 years ago when science was invented.Īnd what an invention! A new way of thinking, involving quantitative observations and mathematical deduction, that gave Western culture an unparalleled power over nature. However, in these days of electric lights, air conditioning, and satellite navigation, no one pays much attention to the sun and stars, anyway. Likewise, the Tropic of Capricorn, marking the sun’s farthest southward excursion, should now be called the Tropic of Sagittarius. We should now properly speak of the Tropic of Taurus. Today, the midsummer sun is in the constellation Taurus it has slipped westward among the stars because of a slow wobble of the Earth’s axis. Or rather, the sun was in the constellation Cancer thousands of years ago when astronomers figured all of this out. This is the farthest north the sun ever gets in the sky.Īt that time the sun is in the constellation Cancer as seen against the invisible background stars. On midsummer day at noon, the sun stands at the zenith, burning a hole in the top of your head. Not far along the beach from where I was staying is a concrete slab with “23° 26′ 22.07″ North of the Equator” in big letters. Just back from a sunny sojourn on the Tropic of Cancer.
0 Comments
Leave a Reply. |