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On the History of Astronomy The emergence of the solar system and of the universe has been an object of mythology and religion since the beginning of human history. There has hardly been a folk on this earth that has not had its own explanation for the emergence or creation of the earth and the heavenly bodies. Even in the beginnings of civilization, the systematic observation of the celestial bodies was set into motion. Babylonians and Egyptians, Chinese and Mayas must developed a working knowledge of the path of the sun and the stars and done so completely independent of one another, as can be mainly deducted from the alignment of their rituals and calendar. In European culture, it was the Greeks, who first tried to explain observations with thought and have passed down their observations and realizations to us in writing. Aristarch of Samos (310 – 230 B.C.) realized that the sun was the middle point of the orbiting planets and round earth. The earth’s rotund form was correctly based upon the observation that a ship’s mast is the last thing to disappear upon its approach toward horizon from the perspective of the land-dweller. Another such observation is that the shadow of the earth during a new moon is always circular, which only could be the case if a sphere. These teachings obviously contradicted the observation that the sun moves across the dome of the sky. Ptolemy from Alexandria (100 – 160 A.D.) postulated like Aristotle (384 – 322 B.C.) that Earth was the center of the universe (geocentric view). The crystal dome of the sky turned above the earth, on which the sun, planets, and stars were fastened. The planets would have to been on very complicated paths for this postulate to even somewhat agree with observation, however. Eratosthenes (276 – 195 B.C.) and especially Strabon (63 B.C. – 26 A.D.) calculated the size of Earth, based on observations, coming to within only one percent of the actual value. The Romans, who followed as the rulers of the ancient world, were not concerned with such problems. They expanded their empire from war, politics, and business. The Roman empire fell, and its successors would be the Christian emperors and kings, who followed the teachings of Ptolemy, because they fit well into the Old Testament’s creation story. In the Middle Ages, the Roman Church assumed an increasingly prominent roll; Astronomy had to heed to religion and became limited in that it could not question the fairly literal interpretation of the Bible. Even the spherical nature of Earth was denied. The Astronomers of the Middle Ages were more or less Astrologist, who told horoscopes and foretold the future, attempting to base them on the orbits of the planets. The writings of the Greek “heathens” were destroyed for their godlessness, and only the Arabian world took up the inheritance of the Greeks. The Arabs gave the brightest stars the names that are partly still used. It was first in the 15th and 16th Century that brought about a change. Scientists began to use their intellect to explain the things that they saw. Nicolas Copernicus (1473 – 1543) at least partially studied translated Arabian writings from the ancient Greeks to develop and publicize (in the year of his death!) the theory, which described celestial bodies as spherical, the sun as the middle point of the universe, and the earth and planets in orbit around the sun (heliocentric view). He thought, however, that these orbits were circular, which is why his theory did not exactly correspond to observation. Giordano Bruno (1548-1600) represented publicly supported Copernicus’ theory and thus contradicted the popular view of the Bible, in which the earth is the immobile center of the universe. Since he did not want to renounce his belief, he was sent to prison for 7 years and was burned at the stake. Galileo Galilei (1564-1642) had it a bit easier, because the telescope had just been invented in Holland. Galilei built his own telescope in 1610 and set sight on Venus, seeing phases like those of the moon. He even discovered four moons, revolving around Jupiter. These did not seem to be attached to a celestial dome, through which they would have to move in and out of the dome, and the phases of Venus could only be explained by revolutions around the sun. The break-through seemed to have made it. Notwithstanding, the representatives of the church were wary to accept Galilei’s conclusions and declared the Copernican Teachings to be witchcraft. To avoid being burnt at the stake, Galilei allowed himself to be humiliated in that he renounced his conclusions and “only” was sentenced to life-long house arrest, supposedly murmuring “…and it does move!” upon his sentencing. In 1992, exactly 350 years after his death, the Vatican admitted that Galilei’s sentence was incorrect. At the beginning of the 17th century, Johannes Kepler (1571-1630) developed his famous laws of planetary motion. These laws dictated on the whole that the planets moved on elliptical orbits around the sun and moved more quickly on these orbits upon increasing proximity to the sun. With the help of his laws, the exact location of the planets could be calculated for any point in time. His laws are still used today to calculate the orbits from satellites and space probes. In the Copernican view, the earth and humans were no longer viewed as the center of the universe, being instead the sun. Isaac Newton (1643 – 1727) dictated that the laws of gravity were the reason for the planetary orbits, and the Copernican theory was finally accepted by scientists for all time. Even Immanuel Kant (1724-1804) guessed correctly that the Milky Way is composed of innumerable stars, of which the sun is only one of many. He even went as to say that the fuzzy specks, seen in telescopes, to be galaxies, of which the Milky Way is only one of. It was not until many years later that such assumptions were confirmed. Albert Einstein (1879-1955), the most ingenious mind of the 20th century, developed his Theory of Relativity and Max Planck (1858-1947) his quantum mechanics, allowing the tools to more fully understand the universe’s proceedings. Edwin P. Hubble (1889-1947) discovered galaxies’ infrared shift in its electromagnetic radiation, which is analogous to the Doppler Effect* in pressure waves, allowing the estimation of galaxies’ distance from Earth. The galaxies seem to be in an immense amount of space that is expanding at a high speed that is higher at points that are further away like two points on an expanding balloon, whereby all points get further away from each other with time. The moment was calculated back in which all matter would be at a single point in space, at which point the expansion was first set in motion, similar to an explosion. The Big Bang Theory was thus born. Through enormous improvements in observation technology, measuring methods, and the use of constantly more powerful computers, it has been possible in the last few decades to make the great advances in astronomy and cosmology. For example, it can by no means be ruled out that our universe is not one of countless others. The most spectacular event in astronomy and the technology of the 20th century was certainly the first manned flight to the moon, on which Neil Armstrong became the first human to step onto the moon on the 21st of June in 1969 (“A small step for man, a giant leap for mankind.”) Even though today almost all observations and computations lead to the conclusion that the universe began in an original explosion, it still remains a theory, because not all things in space are near being understood. Perhaps, it will never be within the grasp of mankind to understand the beginnings of all things, and even less likely that why everything is the way it is will become evident. Nonetheless, as long as man exists, there will be the will to research, and the lust for knowledge will remain the reason for him to wish to be able to explain and understand the things around him. * The Doppler-Effekt is understood as the fact that we hear a higher pitch (shorter waves and higher frequency) of a pressure wave, i.e. sound, from something (a car, for example) that is moving toward us than that of something moving away from us, which is a lower pitch (longer waves, i.e. lower frequency). When speaking of light, we perceive the longer waves as redder and the shorter waves as bluer than they actually are. Resultantly, the movement and distance of a galaxy can be estimated with some degree of accuracy. The text was taken from the brochure for the Schwarzbach Planetary Way www.planetenweg.de
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