Comets, Cosmology and the Big Bang

A history of astronomy from Edmond Halley to Edwin Hubble

Allan Chapman

• Publisher: Lion Books
• Year: 2018
• Print ISBN: 9780745980317
• eBook ISBN: 9780745980300
• Edition: 1
• Topic: Physical Sciences
• Subtopic: World History

This book will take the story of astronomy on from where Allan Chapman left it in Stargazers, and bring it almost up to date, with the developments and discoveries of the last three centuries.

He covers the big names - Halley, Hooke, Herschel, Hubble and Hoyle; and includes the women who pushed astronomy forward, from Caroline Herschel to the Victorian women astronomers.

He includes the big discoveries and the huge ideas, from the Milky War, to the Big Bang, the mighty atom, and the question of life on other planets. And he brings in the contributions made in the US, culminating in their race with the USSR to get a man on the moon, before turning to the explosion of interest in astronomy that was pioneered by Sir Patrick Moore and The Sky at Night.

Chapter 1

From the Beginning to 1700: The Origins of Astronomy

It was in the sixteenth and seventeenth centuries that modern astronomy was born: the astronomy of cosmological vastness, of planets, not as lights in the sky but as spherical worlds encircling the sun, of a Milky Way composed of millions of individual stars, and of strange, feebly glowing “nebulae” or cloudy patches seen against a black sky. This “new” universe came about, however, not because some enlightened intellectual crusaders dared to think for themselves, or challenge the blind Church dogma of mythology, but because of new unexpected discoveries, made with instruments of ever-increasing precision, and, after 1609, with telescopes. The “new” astronomy was created by a progressive technology, developed first in the Greco-Roman world, and then the Middle Ages, as Western Europeans in particular became enchanted by precision devices such as complex mechanical clocks, astrolabes, and sundials, and by sophisticated musical organs, magnetic compasses, Gothic cathedral technology, guns, experimental optics, naturalistic oil painting, and, by 1450, the printing press. All this was driven by an increasingly prosperous Europe-wide market economy. But if these were the essential preconditions for the Renaissance watershed, how had astronomy originated in the first place?

THE ORIGINS OF ASTRONOMY

It is generally agreed that astronomy is the oldest of the sciences. By a “science”, I mean a body of ideas founded upon a logical structure and verifiable predictability. Astronomy’s logical and demonstrable roots were established long before medicine, botany, chemistry, and biology became precise sciences, having graduated from being observation-based, speculative arts, based on hunches and accumulated experiences.

A Babylonian magus of 2000 BC, for example, could confidently predict how many days must come before the next new moon, while the Judean vineyard owner knew how many weeks or months must run their course before his grapes were ready for harvest. The heavens provided a permanent and unchanging backcloth against which life could be measured, for people knew the seasons and constellations of their ancestors’ days would still be there when their great-grandchildren were ancient.

Everything else was a lottery. A virulent epidemic would kill one man, yet his wife would escape unscathed. A herbal concoction would cure one person, and kill his neighbour. One wolf might run away howling when you threw a stone at it, another would turn and maul you. Snakebites sometimes killed, yet occasionally did not. A lump of copper stone heated in a crucible might yield an abundance of useful metal, or might not. And why did milk turn sour and wine become vinegar? Yet the times, seasons, planets, and constellations ran through their eternal and predictable courses – world without end.

THE EARLIEST ASTRONOMERS

The oldest human cultures for which we possess written records, such as those of Egypt, Babylon, India, China, and Israel, all left astronomical records of some sort. They might, like the Chinese and Babylonian, be meticulous records of eclipses, comets, and maximum elongations of Venus from the sun (the Babylonian goddess Ishtar, the curiously horned star of legend). From ancient times, the Chinese imperial sky-watchers recorded the appearance of guest stars, now known to be supernovae exploding in deep space, and this provides valuable pieces of data for present-day astronomers and astrophysicists, studying the cosmological detritus of “supernovae remnants”.

It is fascinating to speculate how high-civilization cultures, from Egypt to China, developed coherent cosmologies that had much in common. These cultures often had trade relations with each other, as the archaeological record shows. The Old Testament tells of active relationships of trade, diplomacy, and war between Egypt and Babylonia, often with little Israel – “the (defenceless) Belgium of the ancient world”¹ – acting as a reluctant highway between them. When you were in Nineveh or Babylon, you had only to sail down the Euphrates for 800 miles, and you reached Ur of the Chaldees, Abraham’s supposed birthplace; go a bit further, you were in the Persian Gulf. Hug the coast for another 1,300 miles around the Indian Ocean, and you would arrive at the Indus, with a culture extending back to at least 3000 BC. Unsurprisingly then, nineteenth-century European Sanskrit scholars found ancient Indian constellation names that may have been the originals behind Perseus, Andromeda, and Orion.² Spices, gold, and exotic artefacts travel across trade routes; ideas of all kinds may do likewise.

In many ways, Chinese astronomy, ancient as it was, seems to have developed within a different cultural orbit, extending primarily to Indonesia and Japan. But the presence of jade artefacts in Indian, Babylonian, and even European archaeological digs reveals that some kind of trade with China passed through Indonesia to India, before crossing the great Asiatic steppe, the future fabled Silk Road to the East.

Whether one were an Egyptian, a Babylonian, or a Hebrew in c. 1500 BC, the abundance of surviving records reveals a common-sense cosmology that looked something like the following. The earth was flat: a perfectly reasonable conclusion to draw if, no matter how far you walked or rode your donkey, a distant flat horizon always unfolded before you. Also, your land was special, for a great, life-giving, north- or south-flowing river irrigated it, be it the Nile, the Euphrates, or the Jordan: Middle Eastern rivers bounded east and west by arid desert, or the Mediterranean “Great Sea”. Your cultural specialness was apparent daily, when the sun rose to its highest noonday point above your river, as if conferring a blessing.

The sky above was envisaged as a vault, or tent, or for the ancient Hebrews, a “tabernacle”, probably supported by four distant pillars. Beneath its canopy, the sun, moon, stars, and planets described their exact and eternal celestial journeys. Generally speaking, these astronomical bodies were believed to pass under the earth at night, to be born afresh at dawn; the ancient Egyptians maintained nocturnal services in their temples to ensure the sun’s (or Ra’s) safe passage through the twelve subterranean gates. The elaborately painted tomb of Pharaoh Rameses VI (1144–1137 BC) in the Egyptian Valley of the Kings makes this cosmology explicit, as the body of the sky-goddess Nut encircles the heavens like a slender dancing-girl, arched and balancing on her toes and fingers above a flat world. Twelve maidens represent the hours of the night – perhaps the origin of our division of the day into twelve hours of light and twelve hours of dark. All deeply astronomical.

The Greeks of post-c. 650 BC, however, would develop a very different cosmology: one that would underpin European (and Arabic) astronomy until c. AD 1600, before bequeathing an observational, mathematical, and instrument-based approach to astronomy, starting with the bronze armillary sphere graduated circles and continuing to the Hubble Space Telescope and the International Space Station.

WHAT MADE THE “GREEK EXPERIENCE” CENTRAL TO WESTERN THOUGHT?

Wherever you come from, you are a child of classical Greece. As Greek science was absorbed in translation into the Arab world after c. AD 900, and even into Japan by the nineteenth century, Greek thinking came to constitute the quintessence of Western civilization. By AD 50, Greek became the language through which Christianity would spread, creating a whole new moral, spiritual, and humanitarian framework for the world. Yet why was it Greek thinking, rather than the much older Egyptian or Babylonian, that exerted such a profound influence?

In c. 1200 BC, when Agamemnon, Helen of Troy, Odysseus, and the other characters later immortalized by Homer were supposedly around, Greece was a war-torn, chaotic place where various heroes constantly had fun knocking the stuffing out of each other. Yet by the eighth century BC, something very significant was happening; and the reasons behind it have fascinated scholars for several centuries. First there was Hesiod, c. 750 BC, whose Theogony in many ways invented theology, or the study of the origins, nature, and relationships of the gods. Hesiod’s Works and Days then praises not the superhero soldier, but the farmer, whose careful tillage peacefully fed the population, while making references to the heavenly bodies and their relationship to the seasons. After c. 640 BC, one meets a crucial innovation: philosophy, mathematics, geometry, and astronomy. Thales and Pythagoras exercise their brains upon the properties of circles and triangles, and the exact mathematical sequences of the astronomical bodies. How much they drew upon practical aspects of Babylonian astronomy – such as the sun moving through a single digit (or degree) of its annual course each day of the assumed 360-day year – we cannot be sure. But most likely their basic sky geography of the twelve signs of the zodiac and constellation boundaries were inherited from Babylon.

We cannot be sure whether Thales and Pythagoras ever wrote their ideas down or passed them on through an oral teaching tradition, to be written down by later disciples. But we do know that they, and their ideas, made a formative and indelible impression on the Western mind: and most of all, on astronomy, with the proposition that mathematics contained eternal truths that transcended mere numerical reckoning. The Babylonians had been experts in reckoning and recording numerical data, such as those used in tax collection or astrology, while Egyptian surveyors were masters of lines and triangles, and able to delineate who owned what piece of ground when the annual Nile flood receded, as well as laying out monumental architecture such as pyramids and ziggurats. What the Greeks did, however, transcended the practice of mathematics as just a useful form of social technology: they saw it, rather, as possessing a compelling philosophical power.

As far as we can tell from surviving clay tablets and papyri, the Babylonians and Egyptians did not ask why two plus two cows always equalled four cows, or why circles and triangles had useful properties when it came to surveying a field. Yet the Greeks did; and by the time of Thales and Pythagoras after 600 BC, these questions were being considered in a big way. Was it not wonderful that the radius of a circle unfailingly divided into the circumference 6.8 times? And that the areas of two squares erected on the shorter sides of a right-angled triangle always added up to the area of a square on the longest, hypotenuse, side – Pythagoras’ famous Theorem? It was the Greeks who turned geometry and arithmetic from useful skills into precise intellectually coherent sciences, and when they were applied to the celestial bodies, astronomy became a science as well.

Just think, blasé as we may be about it today, of the sheer intellectual force behind the realization that the same numerical reckoning tools used to count a flock of sheep or mark out a field boundary also applied to the great and small cycles of the sun, moon, and planets, and with stunning and repeatable accuracy. These techniques, moreover, could be developed and taught to others, leading on to a precise accumulation of systematic knowledge. Mathematics and astronomy were not the only sciences, or publicly demonstrable intellectual disciplines, to which the Greeks paid attention. There were also philosophy and linguistics, the arts of thinking, speech, and coherent communication, the politics of the negotiated public space as opposed to the tribal hierarchy, economics, music as a mathematical discipline, rational medicine, and even organized sports, such as the Olympic Games. The Greeks, too, invented public theatre and plays that pursued a particular theme, encompassing the classical tragedies of Aeschylus and the bawdy comedies of Aristophanes, which still make us alternately cry and laugh.

Over the centuries, many scholars have wrestled with what caused the Greek experience, and why it was so formative in the development of subsequent Roman and Christian medieval European civilizations. I have made my own suggestions in my previous writings.³ Perhaps the independent-minded commercial and intellectual initiatives that developed with the city-state system after c. 700 BC played a significant part, along with Greek philosophical ideas of the world embodying a coherent unifying intelligence, referred to variously as the logos or the nous. This world was not the plaything of warring gods and spirits, but embodied a rationality of which the human race was a part. Greek astronomy cannot be seen in isolation; to make sense of its formidable influence, it must be viewed as a part of the wider cultural and philosophical package. By c. 600 BC, the Greeks had come to realize, perhaps as a result of their sea-voyaging and travel, that the earth was a sphere and not a flat plane; by 300 BC Eratosthenes had even made a remarkably good reckoning of its size, based upon shadows and geometrical projections. By 125 BC, Hipparchus had made a list of constellations, no doubt based upon Babylonian predecessors, and from a mathematical analysis of already ancient Egyptian in comparison with modern data, deduced the existence of the precession of the equinoxes: a tiny annual slipping back of the equinoxes along the celestial equator. By AD 150, Ptolemy – sometimes cited as Claudius – had produced a star-map, whose basics we still use today, as well as formalized the classical geocentric cosmos with its planetary and stellar spheres: all of which accorded elegantly with the best knowledge of the time. As far back as 350 BC, Aristotle had produced a coherent physics, or logical explanation of how matter was formed, behaved, and changed, and how the heavenly bodies might relate to terrestrial bodies. All this was with exquisite rationality from the then best-known common-sense logical knowledge, a million miles from superstitious tales and myths.

MEDIEVAL CONSOLIDATION

For 1,000 years after the slow decline of classical Greco-Roman civilization, by the sixth century AD, the cosmology and physics outlined above (just like its medicine and physiology) formed the bedrock of Christian Europe’s explanations of the heavens and most natural phenomena. Between c. AD 900 and 1400, this system was absorbed into the intellectual traditions of the Arab world, from southern Spain to Iran, largely at the hands of Greek, Syriac, and Mesopotamian Christian and Jewish translators who found themselves living under new Islamic overlords, following Muhammad’s and his disciples’ lightning conquests of their lands between AD 622 and c. 720.

The Islamic world would produce some astronomers of genius between c. AD 950 and 1449. These included great observational astronomers and table calculators, such as Al-Battani, Thabit ibn Qurra, Al-Zarqali, and Ulugh Beg, along with planetary dynamic mathematical theorists and calculators such as Nasir al-Din al-Tusi of the Maragha Observatory in Persia. The observatories at Maragha, Samarkand, and elsewhere used enormous Greek-derived 90º quadrants and circles to measure tiny angles between astronomical bodies, so that this data could be used to compute refinements to the geocentric cosmology of the classical Greeks, and to work out precise corrections that could be applied when comparing Greek observations of 125 BC or AD 150 with those made in AD 1000.

Like the Europeans, the Arabs fell in love with mathematics and geometry, and began to devise ingenious angle-measuring instruments, often inspired by Ptolemy’s Almagest of c. AD 150, such as the astrolabe. Consisting of a set of angle-graduated brass plates, usually between 5 and 10 inches in diameter, incorporating a rotating star map and engraved tables, this would become the quintessential medieval astronomical instrument. It could be used to measure celestial angles, find the local time, or compute the rising and setting times of the sun,...

Table of contents

• Cover
• Title Page
• Copyright
• Dedication
• Contents
• Acknowledgments
• Preface
• 1. From the Beginning to 1700: The Origins of Astronomy
• 2. Cosmology Begins at Home: Captain Edmond Halley, FRS, RN, Astronomer, Geophysicist, and Adventurer
• 3. Could a Comet Have Caused Noah’s Flood?
• 4. “Let there be more light.” How Telescope Technology Became the Arbiter in Cosmological Research
• 5. The Rector and the Organist: Gravity, Star Clusters, and the Origins of the Milky Way
• 6. William and Caroline Herschel Fathom the “Construction of the Heavens” from an English Country Garden
• 7. Measuring the Heavens and the Earth in Eighteenth-Century Europe: Part 1: In Pursuit of Venus: Astronomy’s First Great International Adventure
• 8. Measuring the Heavens and the Earth in Eighteenth-Century Europe: Part 2: Pendulums, Planets, and Gravity: Creating the Science of Geodesy
• 9. Cosmology and the Romantic Age
• 10. Sir John Herschel: The Universal Philosopher of the Age
• 11. There Must Be Somebody Out There!
• 12. Mary Somerville: Mathematician, Astronomer, and Gifted Science Communicator
• 13. Sir George Biddell Airy of Greenwich: Astronomer Royal to the British Empire
• 14. Barristers, Brewers, Peers, and Engineers: Paying for Astronomical Research: the British “Grand Amateur” Tradition
• 15. The Camera Does Not Lie: The Birth of Astronomical Photography
• 16. Unweaving the Rainbow: Part 1: Sunlight, Sunspot Cycles, and Magnetic Storms
• 17. Unweaving the Rainbow: Part 2: Cosmologists and Catholic Priest Pioneers of Astrophysics
• 18. The Revd Thomas William Webb and the Birth of “Popular Astronomy”
• 19. “Ladies of the Night”: The Astronomical Women in Great Britain and America
• 20. Astronomy for the Masses in the Victorian Age and Early Twentieth Century
• 21. Under New World Skies: The Great American Observatories
• 22. On the Eve of the Watershed: Astronomy and Cosmology c. 1890–1920
• 23. It’s All Relative. The “Alice in Wonderland” World of Early Twentieth-Century Physics
• 24. Crossing the Watershed: Edwin Hubble, the Celebrity Astronomer of the Galaxies
• 25. The Belgian Priest–Cosmologist and the “Cosmic Egg”
• 26. Sir Bernard Lovell and the “Radio Universe”
• 27. “Fly Me to the Moon”: The Birth of the Space Age
• 28. A Universe for the People: Sir Patrick Moore and the New Amateur Astronomy
• 29. Postscript: Creation Revisited: Where Do We Stand Today?
• Appendix: The Cock Lane Ghost, or the “Ghost Catch”
• Notes
• List of In-text Illustrations
• Further Reading
• Index