History And Impact Of Astronomy
Ancient ruins provide evidence that the most remote ancestors observed and attempted to understand the workings of the Cosmos. Although not always fully understood, these ancient ruins demonstrate that early man attempted to mark the progression of the seasons as related to the changing of the apparent changing positions of the Sun, stars, planets and Moon on the celestial sphere. Archaeologists speculate that such observation made more reliable the determination of times for planting and harvest in developing agrarian communities and cultures.
The regularity of the heavens also profoundly affected the development of indigenous religious beliefs and cultural practices. For example, according to Aristotle (384–322 B.C.), Earth occupied the center of the Cosmos, and the Sun and planets orbited Earth in perfectly circular orbits at an unvarying rate of speed. The word astronomy is a Greek term for star arrangement. Although heliocentric (Sun-centered) theories were also advanced among ancient Greek and Roman scientists, the embodiment of the geocentric theory conformed to prevailing religious beliefs and, in the form of the Ptolemaic model subsequently embraced by the growing Christian church, dominated Western thought until the rise of empirical science and the use of the telescope during the Scientific Revolution of the sixteenth and seventeenth centuries.
In the East, Chinese astronomers, carefully charted the night sky, noting the appearance of "guest stars" (comets, novae, etc.). As early as 240 B.C., the records of Chinese astronomers record the passage of a "guest star" known now as Comet Halley, and in A.D. 1054, the records indicate that one star became bright enough to be seen in daylight. Archaeoastronmers argue that this transient brightness was a supernova explosion, the remnants of which now constitute the Crab Nebula. The appearance of the supernova was also recorded by the Anasazi Indians of the American Southwest.
Observations were not limited to spectacular celestial events. After decades of patient observation, the Mayan peoples of Central America were able to accurately predict the movements of the Sun, Moon, and stars. This civilization also devised a calendar that accurately predicted the length of a year, to what would now be measured to be within six seconds.
Early in the sixteenth century, Polish astronomer Nicolaus Copernicus (1473–1543) reasserted the heliocentric theory abandoned by the Greeks and Romans. Although sparking a revolution in astronomy, Copernicus's system was deeply flawed by an insistence on circular orbits. Danish astronomer Tycho Brahe's (1546–1601) precise observations of the celestial movements allowed German astronomer and mathematician Johannes Kepler (1571–1630) to formulate his laws of planetary motion that correctly described the elliptical orbits of the planets.
Italian astronomer and physicist Galileo Galilei (1564–1642) was the first scientist to utilize a newly invented telescope to make recorded observations of celestial objects. In a prolific career, Galileo's discoveries, including phases of Venus and moons orbiting Jupiter dealt a death blow to geocentric theory.
In the seventeenth century, English physicist and mathematician Sir Isaac Newton's (1642–1727) development of the laws of motion and gravitation marked the beginning of Newtonian physics and modern astrophysics. In addition to developing calculus, Newton made tremendous advances the understanding of light and optics critical to the development of astronomy. Newton's seminal 1687 work, Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy) dominated the Western intellectual landscape for more than two centuries and proved the impetus for the advancement of celestial dynamics.
Theories surrounding celestial mechanics during the eighteenth century were profoundly shaped by important contributions by French mathematician Joseph-Louis Lagrange (1736–1813), French mathematician Pierre Simon de Laplace, (1749–1827) and Swiss mathematician Leonhard Euler (1707–1783) that explained small discrepancies between Newton's predicted and the observed orbits of the planets. These explanations contributed to the concept of a clockwork-like mechanistic universe that operated according to knowable physical laws.
Just as primitive astronomy influenced early religious concepts, during the eighteenth century, advancements in astronomy caused significant changes in Western scientific and theological concepts based upon an unchanging, immutable God who ruled a static universe. During the course of the eighteenth century, there developed a growing scientific disregard for understanding based upon divine revelation and a growing acceptance of an understanding of Nature based upon the development and application of scientific laws. Whether God intervened to operate the mechanisms of the universe through miracles or signs (such as comets) became a topic of lively philosophical and theological debate. Concepts of the divine became increasing identified with the assumed eternity or infinity of the Cosmos. Theologians argued that the assumed immutability of a static universe, a concept shaken by the discoveries of Copernicus, Kepler, Galileo and Newton, offered proof of the existence of God. The clockwork universe viewed as confirmation of the existence of a God of infinite power who was the "prime mover" or creator of the universe. For many scientists and astronomers, however, the revelations of a mechanistic universe left no place for the influence of the Divine, and they discarded their religious views. These philosophical shifts sent sweeping changes across the political and social landscape.
In contrast to the theological viewpoint, astronomers increasingly sought to explain "miracles" in terms of natural phenomena. Accordingly, by the nineteenth century, the appearance of comets was no longer viewed as direct signs from God but rather a natural, explainable and predictable result of a deterministic universe. Explanations for catastrophic events (e.g., comet impacts, extinctions, etc.) increasingly came to be viewed as the inevitable results of time and statistical probability.
The need for greater accuracy and precision in astronomical measurements, particularly those used in navigation, spurred development of improved telescopes and pendulum driven clocks that greatly increased the pace of astronomical discovery. In 1781, improved mathematical techniques combined with technological improvements along with the proper application of Newtonian laws, allowed English astronomer William Herschel to discover the planet Uranus.
Until the twentieth century, astronomy essentially remained concerned with the accurate description of the movements of planets and stars. Developments in electromagnetic theories of light and the formulation of quantum and relativity theories, however, allowed astronomers to probe the inner workings of the celestial objects. Influenced by German-American physicist Albert Einstein's (1879–1955) theories of relativity and the emergence of quantum theory, Indian-born American astrophysicist Subrahmanyan Chandrasekhar (1910–1995) first articulating the evolution of stars into supernova, white dwarfs, neutron stars and accurately predicting the conditions required for the formation of black holes subsequently found in the later half of the twentieth century. The articulation of the stellar evolutionary cycle allowed rapid advancements in cosmological theories regarding the creation of the universe. In particular, American
can astronomer Edwin Hubble's (1889–1953) discovery of red shifted spectra from stars provided evidence of an expanding universe that, along with increased understanding of stellar evolution, ultimately led to the abandonment of static models of the universe and the formulation of big bang based cosmological models.
In 1932, American engineer Karl Janskey (1905–1945) discovered existence of radio waves of emanating from beyond the Earth. Janskey's discovery led to the birth of radio astronomy that ultimately became one of the most productive means of astronomical observation and spurred continuing studies of the Cosmos across all regions of the electromagnetic spectrum.
Profound questions regarding the birth and death of stars led to the stunning realization that, in a real sense, because the heavier atoms of which he was comprised were derived from neucleosynthesis in dying stars, man too was a product of stellar evolution. After millenniums of observing the Cosmos, by the dawn of the twenty-first century, advances in astronomy allowed humans to gaze into the night sky and realize that they were looking at the light from stars distant in space and time, and that they, also, were made from the very dust of stars.
Science EncyclopediaScience & Philosophy: A-series and B-series to Ballistic Missiles - Categories Of Ballistic MissileAstronomy - History And Impact Of Astronomy, The Science Of Astronomy, Quantifying Light—luminosity And Spectral Classes, Spectroscopy