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March 23, 2013

The Solar System

A star and its family

For a long while, we delved in the distant universe. That gave you a fairly good idea of, firstly, how the universe came into being in the first place; secondly, what were the earliest forms that took shape from the cataclysmic event. It is time we examined in depth what lies closer to home -- the Solar System. That will give us an idea of how space a few billion miles across may look like, and, the things it may possess. All pictures of the Solar System are imaginary, often drawn to the scale, imaginary nevertheless. So, our own assessment, in some cases, may be based on educated guess, deep contemplation and basic knowledge about space, as well as physics. You may rely on it. The word ‘solar’ comes from the Greek word Sol, meaning, sun. Another word used in the same sense is Helios, again pertaining to the sun. That is the reason why the system of the Sun, its planets, moons and whatever else, came to be called, Heliocentric system, after discoveries by the irrepressible Nikolai Copernicus (1473-1543), a Polish churchman, in 1543. This marked the start of a new, albeit turbulent, era which was destined to decide the fate of many people but, above all, that of science itself. The violent controversy which lasted for more than a century accounted for many people, among them perhaps the first martyr of science and victim of the church, Giordano Bruno in Rome in 1600 who was burnt alive for insisting that the Sun, and not the Earth lay in the centre of the Solar System. Thus resorting to blasphemy of the worst kind in the eyes of the church. Copernicus rejected the Ptolemaic theory of the Solar System (the World System, as he called it) and instead proposed a plan in which the Sun, not the Earth was the centre of the planetary system. Copernicus knew that his ideas would not meet with the approval of the church, which would only give the central position to the Earth. The holiness allocated to the Earth was absolutely unassailable. Any deviation from what the church held to be true was often punishable with death or severe retribution. To hold that the Earth moved around the Sun was the worst form of heresy. No deviation would ever be tolerated. But the old order was bound to fall flat in the face. Soon! Claudius Ptolemy (120- 180 AD) was an astronomer, mathematician and geographer of the highest class. Despite his many achievements he is best remembered for his ‘world system’, better known as the Ptolemaic, in which the Earth lay at rest at the centre of the Universe and around it moved the moon, planets, Sun and at a great distance, the stars. With Copernican system, the Ptolemaic met its end. There came a time when the church and a few defenders of faith, as they called themselves, were the only line of defence left. For gradually, Copernicus won over the rest, or most of them. Astronomy came a long way from the time it was believed that Earth rested on top of a giant turtle, which, to ease its burden floated on water. Yet, it would be unfair not to take into account the work of a few geniuses, particularly among Greeks, Egyptians and Muslims. Though it would be at the risk of deviating from our main topic. Yet a few whose work was of great value were: Thales (born 624BC), Aristotle (384-325 BC), Archimedes (287-212BC), Eratosthenes of Cyrene, who measured the diameter of the Earth with stunning accuracy. The value he discovered was better than that used by Columbus during his voyage across the Atlantic in 1492. Then, in 280BC, Aristarchus of Samos, proved that it is Earth that goes around the Sun and not vice versa. Despite his laborious and pioneering work, he found few takers and the Greeks went back to their old ways. The Earth was the supreme deity once again. Similarly, the Muslim thinkers suffered no less. Their discoveries were found to be odious to the ruling class, and their work was consigned to dustbin, from which others would gain centuries later; in another region, in another epoch. So far I have said enough about the progress science made through the centuries – a cold, dark and dank period in which many radical (for their time) ideas were toppled and not allowed to flourish. But ideas must move on, slowly, gingerly but inexorably to their conclusion, giving birth to yet newer ideas. By the time Tycho Brahe (1546-1601), Johannes Kepler (1571-1630), Galileo Galilee (1564-1642), Issac Newton (1642-1727) and some others made their appearance, astronomy had come of age. By the beginning of the 18th century, it was accepted beyond question that the system to go was the Heliocentric, to the extent that every single thing in the Solar System was obliged to be trapped and orbiting the mighty Sun, some not directly but still. In the post-antiquity age of discovery, Sun was circled by six planets, namely Mercury, Venus, Earth, Mars, Jupiter and Saturn. Soon other planets and their moons would follow, making the total at nine planets, which was later reduced to eight by unjustly excluding the lonesome Pluto. At the beginning of the study of the Solar System, it was necessary to go over the detail of how man painstakingly understood the mechanics of the skies. It is not just the history of science but progress of man through centuries. How he fought the forces unleashed by each new discovery. For he had not only to grapple with his inventions, but also to deal with a lot of those who were constrained to discard the long-held beliefs, and accept the new ones. It was a battle between the old belief system versus new discoveries. From now on the Solar System will take over our field of interest in complete earnest. No detail will be spared in discussing the planets, moons, asteroids, meteorites, shooting stars, comets, gravity, electro magnetism, solar flares, et al. So, until we meet again, it is the Solar System all the way!

The writer is a professional astronomer and a former head of PIA Planetaria. He can be reached at