Astronomy as a Science That Always Intrigued Man - Essay Example

Of Greeks and Astronomy Introduction Astronomy is a branch of science that has always intrigued man. Man has always wondered what is beyond the skies, or if we are alone in this universe. Ancient civilizations, with their keen observation and speculation, has provided the modern world with the foundations of astronomy as we know it today. Greek Astronomy The Greek civilization is a rich source of information when it comes to astronomy. The term astronomy itself comes from the Greek words astron meaning “star” and nomos meaning “law”. Ancient Greeks observed the skies and heavenly bodies and correlated their observations with effects on the seas and their crops. Knowledge on astronomy is also used in navigation, planting strategies, and explaining the origin of earth and its nature. The Greeks incorporated astronomy into their beliefs, mythology, religion and superstitions (Heath, 1991). One of the earliest writings on astronomy is Homer’s Iliad and Odyssey, also known as the oldest-manual of astronomy. It provided information on constellations, stars, eclipses, and meteor showers. It also described how ancient people used stars in traveling both land and sea. Iliad also includes the idea that Earth is flat surfaced, an idea which is widely accepted then (Wood, 1999). It was also said that Thales, one of the Seven Sages or the Seven Wise Men of Greece, was able to predict an approximate time of an eclipse and devised a navigating system using the constellation Ursa Minor (Dreyer, 1953). Ancient Greeks used astronomy as a tool that can aid them in their everyday lives. An example of this is Solon’s calendar. The calendar, which is based mainly from his observation of the moon, which lead to the discovery and understanding of seasons provided the Greeks knowledge with better planting schemes and became vital for good food production (Ehrenberg, 1973). Aside from calendars, Greeks were also introduced to sundials by Anaximader of Miletus around 560 B.C. Although sundials are said to be originally discovered by the Babylonians, the Greeks were able to develop and make various forms of sundials (Aveni, 1989). Many people see the hands of God in studying the heavenly bodies, and the Greeks used astronomy as a means to see, understand and commune with God. As a result, astronomy and religion are closely related in Greek civilization. Names of planets are derived from Greek mythology, which is a great part of their religion (Heath, 1991). Several speculations were made by early Greek philosophers. One of them is Pythagoras, who provided the idea that Earth is spherical and not flat or circular. He recognized that the morning star and evening star is the same, and that it was the planet Venus. He also said that the Earth is at the center of the universe and everything else including the sun revolves around it. Furthermore, he said that the moon as it orbits the Earth is inclined to the Earth’s equator. The idea that Earth is located at the center is based more on religion rather than observation. It was somehow deducted from the idea that since God put man at the center of His creation, Earth as man’s home is also at the center of the universe (Wood, 1999). Meanwhile, Oenopides, another Greek philosopher, determined that Earth itself is inclined in its own axis, and found the angle to be approximately 24°. He also calculated how much time it took for planets to revolve around the universe, which is 59 years (Heath, 1981). Fig. 1.1 Diagram showing the Earth as inclined approximately 24° on its own axis. Furthermore, Aristotle proposed that planetary movements around the Earth are made up of complex circular motions and that the universe are composed of concentric spheres, elaborating that the Earth as well as the Sun and all other planets are spherical in shape. He proved that Earth is spherical using deduction and direct observations. Such observations include the following: 1. the earth’s shadow on the moon is circular; and 2. different stars are both visible in the north and southern latitudes. Aristotle’s ideas are visions of perfection. It is more aesthetic than scientific. In his model of the universe, he said that heavenly bodies are embedded in perfect substance and they move around earth in perfect circles (Dicks, 1970). Aristarchus, however, proposed otherwise. He is the first philosopher to be credited with the idea that it is not earth but the sun is at the center of the universe. He is also the first to attempt calculating the sizes and distances of the sun and moon. He also made various proposals from his observations of the moon such as: 1. moon does not generate its own light, but rather reflects the light received from sun, 2. moon orbits around the earth, and as it rotates around the earth, changes in the moons’ phases can be observed, and finally, 3. the width of the earth’s shadow is the twice the width of moon’s shadow. His proposal of a sun-centered universe however, was not accepted during his time and was only proven correct during the Copernican Revolution (Heath, 1981). Another noted Greek astronomer is Eratosthenes, a mathematician and geographer whose famous contributions are computing the Earth’s circumference, the Earth’s distance from the Sun, as well as longitude and latitude (Nicastro, 2008). Ptolemy on the other hand, made models of how earth and the universe were envisioned during those times. The models consisted of a spherical Earth at the center of the universe, while sun and other planets revolve around it. With these models, he was able to explain that while other heavenly bodies revolve, they rotate within their own spheres as well and other basic planetary movements using the mathematical constructions eccentric, epicycle and equant (Wood, 1999). A. eccentric B. epicycle C. equant Fig. 2.1. Mathematical constructions used by Ptolemy. (a) an eccentric model, showing that the center of the earth is not the center of the universe. (b) an epicycle model, showing a planet revolving around a center as it rotates on its own center. (c) an equant model, showing a center of motion is different from the center. It also demonstrates how a planet revolves around the center but also moves around the center of motion in a uniformly manner. Although most ancient Greek philosophers are men, one should not fail to mention Aglaonike, a noted and possibly the first female Greek astronomer. She is well informed of metonic cycles, which consist mainly of periods of full moon and eclipse cycles, and with these she was able to accurately predict lunar eclipses (Heath, 1991). Though Socrates and Plato are very famous Greek philosophers, they did not contribute much when it comes to astronomy. For Plato, his main interests were about morals, so he lack interest with the sensible world and material things (Taylor, 2001). Conclusion Astronomy was welcomed with enthusiasm at the start of ancient Greek civilization. Discoveries and speculations were made and it increased geometrically. One observation lead to another, and they were practical in nature and were mostly used and utilize in their everyday lives. Some of this such as calendars, sundials and maps were modified and passed on to the modern world. Knowledge on heavenly bodies, seasonal changes, phases of the moon, cycles of the moon were vital information that aids in predicting eclipses and other natural phenomena. Models and graphical constructions were made to further explain the nature and principles of the universe. All these came from the Greeks, and were made with observations and simple materials. But astronomy was tightly related to religion, which limited their speculations resulting to proposals such as the heliocentric idea of Aristarchus to be not accepted. The Greeks accepted speculations that conforms to religion and stopped at that until astronomy was carried on by another civilization and was proven otherwise. Their attention was diverted, discoveries halted and other Greek philosophers like Plato did not bother much with astronomy but concentrated more on other things like morality. References Aveni, Anthony F. Empires of Time: Calendars, Clocks and Cultures. New York: University Press of Colorado, 1989. Dicks, D.R. Early Greek Astronomy to Aristotle. London: Cornell University Press, 1970. Dreyer, J.L.E. A History of Astronmy from Thales to Kepler. New York: Dover Publications, 1953. Ehrenberg, Victor. From Solon to Socrates: Greek History and Civilization between the 6th and 5th Century B.C. United Kingdom: Routledge, 1973. Heath, Thomas L. Greek Astronomy. New York: Dover Publications Inc., 1991 Heath, Thomas L. A History of Greek Mathematics: From Thales to Euclid. New York: Dover Publications, 1981. Heath, Thomas L. A History of Greek Mathematics II: From Aristarchus to Diophantes. New York: Dover Publications, 1981. Nicastro, Nicholas. Circumference: Eratosthenes and the Ancient Quest to Measure the Globe. United Kingdom: St. Martin’s Press, 2008. Taylor, A.E. Plato: The Man and His Work. New York: Dover Publications, 2001. Wood, Florence and Kenneth Wood. Homer’s Secret Iliad: The Epic of the Night Skies. New York: John Murray Publishers, Ltd., 1999. Read More