The Cycles of the Sky and The Origin of Modern Astronomy

Summary of Chapters

The fourth chapter The Origin of Modern Astronomy ' discusses the development of astronomy as scientific field . The author embraces the history from the very beginning , when humans showed curiosity about the lights in the sky , and comes up with modern innovations . From the very first stages of development astronomers tended to understand the movements of the Sun and the Moon , planets and other events , whereas others tended to make precise measurements and to describe the motions of heavenly bodies . Actually , the author distinguishes the following periods in historical

development of astronomy : classical astronomy Copernicus ' times , planetary motion , Galileo Galileo 's times and Isaac Newton 's ideas

Ancient philosophers believed that our Earth was centre of the universe but they assume the Earth remained unmoving . Heavens were perfect and therefore , the circle was assumed to be the only perfect geometrical form . The key idea was that heavens were moving in uniform circular motion . Further , Aristotle argued that the starts , the moon and the sun were carried around the Earth . It was Copernicus who had revised ancient theory of the Earth and its motion . Copernicus devised a heliocentric model with the sun in the centre and stressing that the Earth was rotating on its axis . The Earth was believed the circle the sun within the year

Tycho Brahe offered his own views on the motion of our planet . According his model , the sun and the moon circled the Earth , whereas others planets circled the sun . Tychos ' observations were inherited by Kepler who discovered three laws of planetary motion . Further , Galileo is known to have discovered the telescope , but he was condemned by Inquisition He discovered the phases of Venus , the mountains of the moon , the satellites of Jupiter , etc . Finally , Isaac Newton also changed humanity 's views on nature as he discovered three laws of motion and what is more important , the law of gravity

The fifth chapter provides definition of light and discusses visual-wavelength telescopes , special instruments , radio telescopes and astronomy from satellites . Light is defined as the visible form of electromagnetic radiation , an electric and magnetic disturbance that transports energy at the speed of light (ch .4 ) Electromagnetic spectrum is know to include X rays , gamma rays , visible light ultraviolet radiation , radio waves and infrared radiation . A photon is a particle of the light and it is defined as a bundle of waves . Photon may act as a particle and often as a wave . Actually , photon carries energy to the wave , but everything depends on the wavelengths . The length of the wave is ranging from 400nm to 700nm . Infrared and radio photons have longer wavelength , whereas ultraviolet and x rays have shorter wavelengths and carry , therefore , more energy

In astronomy telescopes are used for gathering light , seeing the tiny details and magnifying the necessary image . Discovery of telescope has significantly contributed the field of astronomy . Astronomers are interested in building telescopes with larger diameters as it offers new opportunities and possibilities for observations . There are many types...