Ancient Greek Astronomy Essay Research Paper Ancient

Ancient Greek Astronomy Essay, Research Paper

Ancient Greek Astronomy

Since the first Egyptian farmers discovered the annual reappearance of Sirius just before dawn a few days before the yearly rising of the Nile, ancient civilizations around the Mediterranean have sought to explain the movements of the heavens as a sort of calendar to help guide them conduct earthly activities. Counting phases of the moon or observing the annual variations of day length could, after many years’ collection of observations, serve as vital indicators for planting and harvesting times, safe or stormy season for sailing, or time to bring the flocks from winter to summer pastures. With our millennia of such observation behind us, we sometimes forget that seeing and recording anything less obvious than the rough position of sun or nightly change of moon phase requires inventing both accurate observation tools (a stone circle, a gnomon used to indicate the sun’s shadow, a means to measure the position of stars in the sky) and a system of recording that could be understood by others. The ancient Greeks struggled with these problems too, using both native technology and inquiry, and drawing upon the large body of observations and theories gradually gleaned from their older neighbors across the sea, Egypt and Babylonia. Gradually moving from a system of gods and divine powers ordering the world to a system of elements, mathematics, and physical laws, the Greeks slowly adapted old ideas to fit into a less supernatural, hyper-rational universe.

As ancient peoples began to realize that sun, moon and stars follow certain rhythms in step with the seasons, they began to hypothesize that some conscious set of rules must be dictating these movements and seasonal changes that, for agrarian or pastoral societies, were a matter of life or starvation. So, to explain the natural phenomena a complicated system of gods’ interactions with men was born.

There are hints of the Greek conception of the universe in Homer, who mentions many subjects on his two epics describing war and the perils of trying to come home after long absence. For Homer, heaven is a solid inverted bowl straddling the earth, with fiery, gleaming “aither” above the cloud-bearing air. Homer mentions the movements of sun, moon, and many stars by name. The fact that Hades is on the underside of earth has an important impact on conceptions of heaven: it is unlit by the sun, therefore, the sun–and by extension, other heavenly bodies– must sink only to the level of Ocean, which is conceived as a river circling earth’s edge. From it the Sun must also rise–though how it gets back to the eastern bank of Ocean is never explained. These popular conceptions of sky are more fully explained in Hesiod, whose works on gods, on agriculture, and animal-herding are more closely connected to the practical application of astronomy. He clocks spring, summer, and harvest by solstices and the rising and setting of certain stars, and notices that the sun migrates southwards in winter

As the Greeks began to travel and explore, their ideas of the order of the universe began to change. Many Greeks settled on the coast of Turkey in the early migrations of the eleventh century BCE, and there enjoyed rich cultural mingling with their neighbors the Lydians and Persians, latest descendents of Mesopotamian civilization. They kept in touch with their western cousins, who began a second wave of settling across the Aegean in the seventh century, as well as with other rich sea-faring cultures like Egypt. It is not surprising that, by the sixth century, these Ionian navigators of the sea began to develop new ideas about the sky they steered by. The most fundamental of these was that the universe might run, not only by the whim of gods, but by physical, mechanical rules and principles that might, through study, be understood and predicted. The sources for all early Greek astronomy are scant, none more so than for Thales, supposedly the first of the philosophers. Various inventions and discoveries are attributed to him, most famous of which is his prediction of an eclipse of 585 BCE. Modern scholars are fairly sure he was able to do this by consulting known Babylonian eclipse and lunar observations going back about 150 years, long enough to notice that eclipses recur after about 18 years. His activities also seem to have included star-observations and trigonometry, which he is credited with having founded, but the details of his theories are either lost or obscured by later legends about this early thinker who left no written record. He seems to have conceived of earth as flat and water-borne, and to have postulated that there must have been some first substance out of which the world arose, which he guesses is water. The next ancient Greek philosopher was Anaximander of Miletus who lived c. 550 BCE. The earth for Anaximander was still a cylinder circled by air and then fire “like the bark of a tree,” which separated off at an early stage. Although his theory still echoes the early cosmologies, it is an attempt to explain the scheme in purely physical–in fact, in mathematical–terms. The heavenly bodies are all described as wheels; their visible light that we actually see is only a part of them, described as an axle, pipe, or vent. These vents opening or partially closing cause lunar variations. All these ideas did attempt to explain the universe in physical