Vital step were taken towards the detection of stellar parallax during the eighteenth century through the collection of extensive and precise stellar catalogues. In addition, more precise instruments, impossible for the crude technologies of earlier times, were being constructed. Both these factors contributed to many false alarms until the actual minuteness of stellar parallaxes was […]
The desire to detect both solar and stellar parallaxes provided great incentive for observational astronomers during the eighteenth century. Lunar distances also were important because observations of the Moon were felt to be a viable approach to the problem of determining longitude at sea. One of the most elaborate scientific expeditions of the eighteenth century […]
Meanwhile, investigations into the physical mechanism of the planets culminated in 1687 with the publication of Isaac Newton’s Principia’. Although others had made important contributions to the question of the mutual attraction of bodies, Newton was the first to assimilate it all and to derive the exact equations for the fall of a body on […]
In the midst of these cosmological expansions, several events culminated in the abolition of the concept of solid, classical spheres required by mechanistic models of the universe. Copernicus Universe deprived the stellar sphere of its earlier function as the driving force behind celestial motions. A succession of uncommon celestial events showed that the spheres were […]
Mediaeval astronomical measurements assumed the model of a two sphere Universe. This model postulated the segregation of Earth and sky: the laws of motion and the constitution of the heavens were considered quite separately from the physical relationships governing the behaviour of matter on the Earth. Philosophers considered the heavens to be perfect and unchangeable: […]
Early Measurements of The Universe A spherical Earth was accepted very early, although the first conclusive physical argument in favour came from Aristotle. He pointed out that during a lunar eclipse the shadow cast by the Earth on the Moon was circular, which would not be the case unless the Earth were spherical. Aristotle alluded […]
Towards the middle of the eighteenth century, European rather than British mathematicians began to investigate the remaining problems in the lunar and planetary theories. Although Newton had provided a solid foundation for the theory of the motions of the Moon and planets, he was not able to account for all the inequalities in their orbits. […]
Isaac Newton’s ‘Mathematical Principles of Natural Philosophy’ (or ‘Principia’) was published in 1687. This work dealt with observed properties of bodies and their motions from which could be derived certain general laws relating to the forces of nature, general laws that could be used to predict other natural phenomena. The ‘Principia’ was divided into three […]
The Copernican theory fitted the planet orbits of small eccentricity (Venus, Earth. Jupiter and Saturn), but, as with the Ptolemaic-theory, Mars remained a problem. Discrepancies of more than a degree, unacceptable by any observational standards, still persisted. To Johannes Kepler (1571- 1630). enthralled with the beauty and symmetry of the heavens, the Copernican fit was […]
Early planetary schemes Behind all the complex hypothetical machinery to move planets through the sky lay a simple aim to predict the positions of planets and the sun and Moon in the foreseeable future in order to cast horoscope, make forecasts and construct a calendar. In achieving these aims, it, did not, matter that the […]