11-08-2007 Astronomy: a brief history (Article 98)

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Simon Kenny
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11-08-2007 Astronomy: a brief history (Article 98)

Post by Simon Kenny » Wed Feb 04, 2009 11:15 am

Astronomy: a brief history (Article 98)

Astronomy is probably the oldest of the sciences. From the earliest times, the regular, cyclical movements of the Sun, Moon, planets and stars were observed and used to reliably predict natural cyclical events, such as the seasons. The Babylonian civilisation produced the first great astronomers in recorded history. They systematically studied the movements of the Sun and Moon nearly 4,000 years ago and developed from this a solar calendar that we essentially still use today. We have also inherited vestiges of their *** numeric system, based on the number 60, still used to measure time and angles. They also defined and named the constellations through which the Sun passes in the course of a year: The Zodiac.

The ancient Egyptian’s saw the heavens as the realm of the gods, who controlled events on Earth, and identified the Sun and Moon with their major deities, Re and Thoth. They also used the stars to predict important events. For example, when Sirius, the sky’s brightest star, emerged from behind the Sun in the dawn sky, they knew the annual Nile Flood was about to restore life to the land. The same practical reasons probably inspired the building of the great megalithic observatories of Stonehenge and Newgrange. While their importance as religious centres is not in doubt, their importance as astronomical observatories was also crucial. These sacred structures empowered Neolithic farmers to read the minds of their gods, to predict the times of sowing and harvesting, the length of the year, even the cycles of the moon and the planets.
The ancient Greeks contributed immensely to the understanding of celestial mechanics. Using geometry, trigonometry and geography, they were among the first to use strictly scientific methods to make fundamental discoveries. Anaxagoras discovered the Moon orbits the Earth and used this to explain eclipses of the sun and moon. Thales deducted that the earth is a sphere, while Aristarchus observed that the earth orbits the Sun. Eratosthenes of Alexandria, ‘the father of Geography’, used the sun’s shadow in two locations along the Nile Valley to calculate the circumference of the earth. His results were amazingly accurate, within one percent of the actual value.
Since earliest times astronomy served religious and scientific purposes. Astronomy was frequently used to predict religious festivals occurring near equinoxes and solstices. Many believed that all future events, social, political and even personal, could be seen in advance in the stars. Thus, astrology and astronomy have coexisted from the beginning, their separate identities often blurred, as happened in the middle ages, when astronomy almost ceased as a science in Western Europe. The star charts, especially of the Zodiac, were of interest only as a basis for some very dubious personality profiles and prevaricating predictions of future events. Today, when the world is awash with astounding astronomical discoveries, astrology is more popular than ever. While scientific fact is fine, better look at the horoscope too, just in case!

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