Beginning in the twelfth century, Arab scholars, scribes and various translators gradually introduced Europe to the science of astronomy as it had developed in Islamic civilisation, based on earlier Hellenistic models (primarily Ptolemy and Aristotle). But once the Catholic Church had decided to adopt the Ptolemaic/Aristotelian geocentric cosmological model as a theological principle, it considered scientists who criticized this model as heretics. Therefore, the Polish scientist Nicolai Copernicus (1473-1544 AD) circulated his heliocentric model anonymously, and his book De Revolutionibus Orbium Caelestrium ('On the Revolutions of the Heavenly Orbs'), was not published until 1543, just one year before his death. In this model, Copernicus postulated that the sun and the stars are stationary and the earth and the planets circulated around the sun in circular orbits.
It was not until 1609, when Galileo invented the telescope, that Aristotle's and Ptolemy's geocentric model of the universe was completely discarded by knowledgeable researchers, and replaced by the heliocentric model (Drake 1990: 145-63). At around the same date (1609-1619), the scientist Johannes Kepler formulated three mathematical statements that accurately described the revolution of the planets around the sun. In 1687, in his major book Philosophiae Naturalis Principia Mathematica, Isaac Newton provided his famous theory of gravity, which supported the Copernican model and explained how bodies more generally move in space and time (Hall 1992: 202).
Newton's mechanics were good enough to be applied to the solar system, but as a cosmological theory it was completely false insofar as it still considered, like Aristotle, the stars to be fixed and the universe outside the solar system to be static. Although a dynamic universe could easily be predicted according to Newton's theory of gravity, the belief in the Aristotelian static universe was so deep and strong that it persisted for some three centuries after Newton (Seeds 1990: 86-107).
In 1718, Edmund Halley compared the positions of stars recorded by the Babylonians and other ancient astronomers with the latest observations and realized that the positions of some of the stars were not the same as they had been thousands of years earlier. Some of the stars were in fact slightly displaced from the rest by a small but noticeable amount. This is called 'proper motion', which is the apparent motion of the star (perpendicular to the line of sight) in relation to the background stars that are very far away. In 1783, William Herschel discovered the solar motion, the sun's motion relative to the stars in its galactic neighbourhood. Herschel also showed that the sun and other stars are arranged like the 'grains of abrasive in a grindstone' (Ferguson 1999: 162-5), which is now called the Milky Way galaxy. More than a century later, in 1924, Hubble was able to measure distances to some stars (based on the 'redshift'), and he showed that some bright dots that we see in the sky are actually other galaxies like ours, although they look so small because they are very far away (Hartmann 1990: 373-5).
The Aristotelian theory of a static universe (i.e., of all the stars) had to be reviewed after Hubble's discovery of the redshift of light coming from all distant stars, which indicated that everything in the universe is actually moving; just as Ibn ‘Arabî had said many centuries before. In his bestselling book of the eighties, Stephen Hawking says:
Even Einstein, when he formulated the general theory of relativity in 1915, was so sure that the universe had to be static that he modified his theory to make this possible, introducing a so-called cosmological constant into his equations.
(Hawking 1998: 42)
This of course was soon proved to be wrong, and everybody now knows that the cosmos is in continuous motion. Einstein himself later considered this to be one of his greatest mistakes. Ibn ‘Arabî, however, declared plainly that the stars can't be fixed at all, and he even gave numbers and units to the speed of their proper motion [III.548.28, II.441.33], which are consistent with the latest accurate measurements.
After these developments, and with the advent of new technologies employed in making even more accurate observations, in addition to accelerated research in physics and astronomy, a whole new view of the cosmos finally replaced the ancient short-sighted ones. However, we cannot ever claim that all the questions have been answered and that we have drawn a fully correct picture of the cosmos. On the contrary, new sets of even more profound questions are still a riddle, such as dark matter and the Einstein- Podolsky-Rosen (EPR) paradox (see section VII.6).
Along with the vast amount of data collected by telescopes and space shuttles in recent decades, many new theories have arisen to try to explain those observations. The mere concepts of 'time' and 'space' were in focus especially after the strange and courageous ideas of Einstein about relative and curved spacetime were proved by Eddington through the observation of the total eclipse of the sun in 1918 in South Africa. Since then, other theories including Quantum Mechanics, the Field Theory, the Superstrings Theory and Quantum Gravity Theory, have tried to discover and describe the actual relation between material objects and energy, on one hand, and between space and time on the other hand. Yet no fully convincing view has ever been achieved.
 The geocentric view considers the earth to be in the centre of the universe, while the heliocentric view considers the sun to be in the centre. Modern cosmology, however, asserts that the universe, being a closed spacetime arena, doesn't have a centre; any point may be considered a centre, just as any point on the surface of the earth may be considered a centre (with regard to the surface, not to the volume). So whether the earth or the sun is in the centre of the universe is a valid question only with regard to the solar system which was the known universe in early cosmology, but it is no longer valid after discovering the galaxies and the huge distances between stars outside the solar system. It is worth mentioning here that Ibn ‘Arabî clearly asserted that the universe doesn't have a centre [II.677.19].
 For more information about this subject see: Bieńkowski, B. (1972), 'From Negation to Acceptance (The Reception of the Heliocentric Theory in Polish Schools in the seventeenth and eighteenth Centuries)', in The Perception of Copernicus' Heliocentric Theory: Proceedings of a Symposium Organized by the Nicolas Copernicus Committee of the International Union of the History and Philosophy of Science, ed. Jerzy Dobrzycki, Boston: D. Reidel Pub.: 79-116.
 The redshift is the displacement (towards the red side) of the spectral lines of the light emitted by stars when it is received on the earth, and this is due to the high speed of the motion of stars away from us. The amount of the shift towards the red is directly proportional to the distance of the star away from us, and this is how distances to far-away stars and galaxies are calculated with a high degree of accuracy.