Parallax: The Race to Measure the Cosmos

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Macmillan, 2002 - Science - 336 pages
How can we measure the distance to a star? Beginning in ancient Greece, history's greatest scientific minds applied themselves to the problem in vain. Not until the nineteenth century would three men, armed with the best telescopes of their age, race to conquer this astronomical Everest. Parallax tells the fast-moving story of their contest, which ended in a dead heat.

Against a sweeping backdrop filled with kidnappings, dramatic rescue, swordplay, madness, and bitter rivalry, Alan W. Hirshfeld brings to life the heroes -- and heroines -- of this remarkable chapter in history. Characters include the destitute boy plucked from a collapsed building who grew up to become the world's greatest telescope maker; the hot-tempered Dane whose nose was lopped off in a duel over mathematics; a merchant's apprentice forced to choose between the lure of money and his passion for astronomy; and the musician who astounded the world by discovering a new planet from his own backyard.

Generously illustrated with period engravings and paintings, Parallax is an unforgettable ride through time and space.

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A compelling and entertaining history of the search to measure the parallax - the displacement of light around different stars. Many famous players appear and disappear in the race to measure the ... Read full review

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User Review  - Devil_llama - LibraryThing

A compelling and entertaining history of the search to measure the parallax - the displacement of light around different stars. Many famous players appear and disappear in the race to measure the ... Read full review


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Part 1 The Sun-centered model of the cosmos. From Copernicus,De Revolutionibus, 1543. Source: Wolbach Library, Harvard University. 1 Reinventing the Cosmos The sight of stars always sets me dreaming just as naively as those black dots on a map set me dreaming of towns and villages. Why should these points of light in the firmament, I wonder, be less accessible than the dark ones on the map of France? --Vincent van Gogh, The Letters of Vincent van Gogh
We had the sky, up there, all speckled with stars, and we used to lay on our backs and look up at them, and discuss about whether they was made, or only just happened. --Mark Twain, Huckleberry Finn

Free at last! The Earth, wrenched from its central, immobile station in the universe, sailed majestically around the Sun, joining its sister planets and companion Moon in perpetual motion. This according to the Greek philosopher-mathematician Aristarchus of Samos, who proposed the bold rearrangement of the heavens--replacing central Earth with central Sun--more than two thousand years ago. After all, he claimed, the Sun--the "lantern" that illuminates the heavens--more properly belongs on the throne of the universe, radiating its light symmetrically over the family of planets. And the Earth, only a fraction of the Sun''s size according to Aristarchus''s own calculations, must logically circle the larger body. Once a year, Aristarchus maintained, our planet completes its solar circuit, then retraces the identical course again and again, ad infinitum. The other planets--Mercury, Venus, Mars, Jupiter, and Saturn--likewise move around the Sun; like heavenly fireflies, they reveal their individual paths against the backdrop of the night sky. Imagine yourself in Aristarchus''s sandals. The year is 270 B.C. The place is the city of Alexandria at the mouth of the Nile innorthern Egypt. Founded by Alexander the Great in the wake of his campaign of conquest some six decades earlier, Alexandria had grown to become the intellectual and commercial center of the Hellenistic world: a grand galaxy of buildings, monuments, wide ways, and human strivings. Along the boulevardlike Canopic Way, stretching between the Gate of the Sun and the Gate of the Moon, Alexandria''s civic vigor manifested itself in spectacular Dionysian processions, one of which "included a hundred-and-eighty-foot golden phallus, two thousand golden-horned bulls, a gold statue of Alexander carried aloft by elephants, and an eighteen-foot statue of Dionysus, wearing a purple cloak and a golden crown of ivy and grapevines." It was here, after the young Macedonian king''s death, that his general, Ptolemy I Soter, established the Temple to the Muses--the "Museum"--and its extraordinary Library with as many as 500,000 documents and scrolls. (By comparison, the largest medieval European library, the Sorbonne, had less than two thousand volumes by the fourteenth century A.D.) A later regent, Ptolemy III, was an even more ardent "book" collector. He decreed that all travelers arriving in Alexandria were to relinquish any documents of literary or scientific value; these were then added to the Library''s collection. In return, the travelers got cheap papyrus copies of their "donated" works. Ptolemy once paid a hefty deposit to borrow the "state copies" of Aeschylus, Sophocles, and Euripides from the Athenian library, on the premise of transcribing them; the originals never made it back to Athens. Alexandria. Centuries of wisdom gathered in one place, a magnet to the world''s most able intellects. In addition to its rich Library, the Alexandrian Museum had research rooms, an observatory, a zoo displaying exotic species, living quarters, and a dining hall where scholars gathered to dine and debate. Here was an ancient think tank devoted to the arts and sciences, a precursor Institute for Advanced Study, whose collective scholarship became its legacy to future generations--and whose eventual decline under Christian authority in the fourth century A.D. and destruction in 642 A.D. at the hands of Islamic invaders marked one of civilization''s greatest losses. Into this percolating cauldron of ideas, Aristarchus presented his radical theory of the cosmos. Devising a complete, logical system that explained the movements of the heavenly bodies, the alternation of day and night, the occurrence of eclipses, the uneven lengths of the seasons, the phases of the Moon, and a host of other celestial phenomena wasa challenge to the ancients. Their powers of observation were severely limited; they had their eyes and they had their minds, the latter clouded by preconceptions about how the universe should be. Physicists Albert Einstein and Leopold Infeld described what these early scientists were up against: In our endeavor to understand reality we are somewhat like a man trying to understand the mechanism of a closed watch. He sees the face and the moving hands, even hears its ticking, but he has no way of opening the case. If he is ingenious he may form some picture of a mechanism which could be responsible for all things he observes, but he may never be quite sure his picture is the only one which could explain his observations. For the three centuries preceding Aristarchus, virtually every Greek philosopher from Pythagoras to Aristotle had hewn to the belief that the Earth occupied the hub of the universe and that the Sun, Moon, planets, and even the star-studded celestial sphere that was thought to enclose the universe all circled around it. This "geocentric" mindset had gained inexorable momentum, having barged its way into the bedrock beliefs of generations of deep thinkers by the sheer force of its unchallenged longevity. To these proto-scientists of old, the reality of an Earth-centered cosmos was as self-evident as the contrary "heliocentric" scheme apparently was to Aristarchus. The geocentric seed germinated around 600 B.C. in the speculations of Thales of Miletus in Asia Minor. Thales, a merchant who made his fortune in olive oil, traveled widely, investigating natural phenomena and conducting experiments. As Plato tells it, Thales once became so entranced by the sight of the stars that he fell into a well while strolling at night. One of his more impressive feats was a measurement of the height of Egypt''s Great Pyramid from the length of its shadow. Herodotus also credits Thales with predicting the solar eclipse of 585 B.C., which occurred during a pitched battle between the Medes and the Lydians near the River Halys. The combatants were so terror-stricken to see day turn into night that they called an immediate truce. The eclipse did take place, but the story of its prediction is questionab≤ probably no one in 600 B.C. knew how to foretell a solar eclipse. In the arena of cosmology, Thales seems to have taken a cue from his inadvertent dip in the well. He proposed that the universewas constructed around a disk-shaped Earth, which floated serenely in a cosmic ocean. To modern sensibilities, the idea of a water-borne Earth might seem quaint. Yet it marked a turning point in cosmological thought. In previous cosmic models, nothing happened without the intervention of a divine hand. Thales held that his floating Earth formed by natural means, akin to the aggregation of silt that he had observed on the Nile delta. The gods might have initiated the Earth''s formation, but once the process was up and running, they benignly looked on. Anaximander, also from Miletus, modified the model proposed by Thales. Anaximander dispensed with the cosmic ocean entirely and suggested that the Earth-disk was free-floating in space, a revolutionary idea at the time. Around 530 B.C., Pythagoras of Samos, whose name adorns the famous theorem relating the sides of a triangle, began to flesh out the crude geocentric model. He proposed that the Earth was not a disk, but rather a stationary globe, surrounded by a series of eight concentric, transparent spheres, on which were affixed the Sun, Moon, planets, and stars. The steady rotations of these spheres led to the observed motions of the heavenly bodies, including their daily rising and setting. (Aristotle, that ancient voice of authority who helped enshrine the geocentric model, lent his support to the spherical-Earth hypothesis in his treatise On the Heavens, written around 350 B.C. His evidence for a round Earth: the curvature of the Earth''s shadow during a lunar eclipse, the changing array of constellations as one journeys north or south, and the disappearance of ships sailing over the horizon. Nonetheless, the Flat-Earth Society persists to this day.) Planetary motions proved to be more complex than the constant, predictable movement of the stars. Planets sped up and slowed down as they coursed through the sky, and on occasion even looped backwards. Their brightness varied during the year, implying that their distance from the Earth changed. Neither motion variations nor brightness variations were easy to explain in an Earth-centered universe, where each planet supposedly circled the Earth at a fixed distance. Discrepancies between the observed and predicted positions of planets threatened to undo the relatively simple cosmic plan of Pythagoras and his followers. "Observation ... is the pitiless critic of theory," science historian Agnes Clerke has noted. "[I]t detects weak points, and provokes reforms which may be the beginnings of discovery. Thus, theory and observation mutually act and react, each alterna

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