The Day the World Discovered the Sun (8 page)

Peter III was preparing to commit his nation—and the Russian-French-Austrian alliance—to a mass act of strategic suicide. Not out of any inviolable principle or budding pacifism either. The newly crowned
Russian leader, it was said, liked nothing more than playing with his toy soldiers. He was 33.

Chappe looked out at the audience, a gathering of some of the empire's greatest minds. The eminent visitor's lecture, later printed in French in St. Petersburg, gloried in the accomplishments of his mission to Tobolsk.

“Astronomers [have] waited for over a century for the transit of Venus across the sun's disc,” Chappe began. “This phenomenon that seized their fancies seemed all the more important in its promise of a whole new day for astronomy.”
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The guest speaker told his audience that the Venus transit mission from which he'd returned two months previous reflected brilliantly on the larger Russian court. He strategically left out any mention of the Russian astronomers whom the Russian Academy of Sciences had sent into the remote hinterlands for their own Venus transit observations that might compete with Chappe's. One expedition was, so far as can be documented today, never heard from again. But another, led by the astronomer Stephan Rumovsky, did ultimately return with Venus transit data from the Lake Baikal region.
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Rumovsky's work and findings go unmentioned in Chappe's talk, however.

Instead, Chappe discussed his own data and paid genuflecting homage to the empress who had approved of his own Venus transit voyage to Siberia. Chappe told his audience, indeed, that the greatest political leaders reign over societies where the arts and sciences flourish. And without drawing too much attention to the current occupant of the Russian throne, Chappe heaped praise instead on Peter III's grandfather Peter the Great, who, Chappe said, “knew that the sciences and arts are also closely related to their glory.”

Chappe's words resounded through the very same palace that Peter the Great had given over to the creation of a library and academy. To further the academy's mission, the dearly departed Elizabeth had in her dying days offered Chappe the position of imperial astronomer of
Russia. (Or so Chappe claimed, at least. His mentioning such an unconfirmed job offer from the late empress might also have served as a none too subtle dig at the France-hating Russian polymath astronomer Mikhail Lomonosov, who by all rights should probably have been imperial astronomer.) The post of Russia's chief astronomer had lain vacant since 1747, when Chappe's countryman Joseph-Nicolas Delisle had abandoned the office that he'd held for twenty-two years and returned to his native Paris.

Even if the job offer were for real, Chappe evidently had other designs on his future than to remain in St. Petersburg. A second Venus transit was seven and a half years away. And this time, according to the predictions concerning the regions of the earth that would see the whole transit, Russia held little valued real estate. In 1769, locations in or near the Pacific Ocean would instead be some of the world's best destinations.
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Serving the Russian court would not be nearly as strategic a choice to collect some of the best data on earth from the 1769 transit. Jockeying for top position within the Royal Academy of Sciences in Paris at least afforded him the chance.

Chappe also subsequently admitted an underlying prejudice—one that his own mission's financial independence from Mother Russia enabled him to hold. There was, he thought, something about the nation as a whole—perhaps the Russian weather—that made people dumb. “The state of the arts and sciences in Russia implies a defect,” Chappe later wrote, clearly in a more critical mind. “The cause of which must be sought for, either in a want of genius particular to the nation, or in the nature of the government and the climate.”
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Such jaw-dropping candor, of course, was absent from the St. Petersburg lecture hall where Chappe held forth. Rather, he paid his homages and thanked his gracious hosts. The “graces and virtues” of the late Elizabeth, he told the crowd, “cultivate the sciences with great success. . . . What a good omen for the progress of this empire! I see
them [those graces and virtues] contributing to the glory of the nation and of Peter III.”

In July, when Chappe would be in transit to Paris, conspirators plotting with Peter III's German-born wife (and second cousin) Sophie would overthrow her husband and crown Peter's bride the new autocrat of Russia. Peter III's captors thereafter relieved their prisoner of his pulse. And the preternaturally canny foreign empress—who'd learned the Russian language and converted to the Orthodox religion—soon cast off her widow's weeds to rule Russia under her assumed name, Catherine the Great.

Nearly a century before the Venus transit voyages, King Louis XIV established the Royal Academy of Sciences in Paris. At the time, the British had established a new Royal Society, placing England's royal imprimatur on scientific research, at a time when science was gaining economic and political relevance. France did not chance the British taking the lead. Within a year of the academy's founding, Louis's ambitious finance minister, Jean-Baptiste Colbert, set to building it a home—a royal observatory on the southern outskirts of Paris. (From the academy's inception, the navigation problem was central to its existence. Two-thirds of the initial membership of the Royal Academy in 1666 studied either astronomy or geometry.)
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It was to Colbert's stone fortress that Chappe returned in August 1762, after his twenty-one-month voyage into Siberia and back again. Those same ramparts had also become the world's clearinghouse for Venus transit data, and Chappe's colleague within the Academy of Sciences, Jérôme Lalande, was positioning himself as one of the world's leading experts on the Venus transit.

A dwarfish man with a bad back and worse eyesight, Lalande was ill-equipped to make physically taxing expeditions.
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Instead, he made his name as a calculator and a commentator.

On November 18, Lalande wrote a letter to his British counterpart, Nevil Maskelyne, which the
Proceedings of the Royal Society
excerpted. In it, Lalande shared the first round of results the French had acquired from several Venus transit expeditions. He had many to choose from. In Germany, a mathematician reported observations he'd made from the orangery of Schwetzingen Castle near Heidelberg; two farmers near Dresden (in independent observations) made their own amateur measurements of the event; a doctor and a Jesuit monk near Nürnberg and Tyrnau, each transmitted their observations too. In Sweden, the country's queen and prince joined a throng of prominent spectators crowding into the observatory at Stockholm—so crowding the astronomers that they couldn't even see their clock. In France, two Catholic priors in Rouen observed the transit from the astronomical observatory at their monastery; telescopes at an abbey in Paris and episcopal palace near Montpellier tracked the planet's motion across the solar disk. Astronomers in England took to the fields, farms, and observatories across the country, while the Duke of York summoned a London instrument maker to show him the famed transit. The duke's observing party never saw the event due to inclement weather.

Ultimately 120 Venus transit teams from around the world would report two key sets of numbers from the 1761 event: the precise latitude and longitude of their observing station (along with the methods they used to determine their coordinates on the globe) and the time that Venus took to cross the sun. Some also tracked the precise path Venus took across the sun, enabling an independent check of the solar parallax derived from the timing measurements. Some locations, such as Friar Hell's observatory in Vienna and Mason and Dixon's in Cape Town, could only observe the latter half of the transit. In such cases, the observers
reported the exact moment the transit officially ended, when an exiting Venus's outer edge first touched the sun's inner edge.

The data, in aggregate, effectively describe a triangle, with one vertex at the center of the sun, another at the center of the earth, and the last vertex at an outer edge of the earth's disk as seen from the sun. (Precisely how one gets from timing and latitude/longitude data to this triangle can be found in the Technical Appendix at the end of the book.) The triangle is superthin: the angle between the triangle's two long arms is so small that if it were a wedge of pie, one could serve up another 144,000 similarly slim pieces before cutting into a second pie.

That angle is called the “solar parallax.” It's close to the slight angular shift of the sun's position in the sky when observations from the equator are compared to observations from the North Pole. (The angular shift would be exactly the same as the solar parallax but for the fact that the earth also spins on an axis that's tilted compared to its orbital plane. In any event, parallax can be readily demonstrated by holding up a pencil at arm's length and closing the left eye and then the right eye. The left-eye/right-eye parallax is approximately 1,400 times bigger than the solar parallax.)
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Lalande found, as he reported to Maskelyne, that all the French expeditions taken in total yielded a solar parallax of 9.55 arc seconds—translating to 85.3 million miles distance from the sun. Lalande added that a fellow French astronomer, Alexandre Guy Pingré, had recently returned from observing the Venus transit on the Indian Ocean island of Rodrigues. And Pingré had derived the same value for the solar parallax.

Later analysis would reveal that Pingré had in fact arrived at a substantially different answer: 10.6 arc seconds or 76.8 million miles.
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But Pingré's putative confirmation of Lalande's result was all Lalande needed to conclude that France was in the right. Maskelyne had previously reported his first analysis of the solar parallax: 8.6 arc seconds. But Lalande
dismissed the English number as the result of flawed data from Swedish observations of the transit. (Lalande was wrong. As present-day observations reveal, the correct answer that everyone was chasing was 8.794 arc seconds.)

Lalande further marveled at reports coming in from the field that some observers had difficulty pinpointing the exact moment when Venus's silhouette touched the sun's edge. The “black drop effect” had blurred the precision timing of this crucial instant by seconds or minutes. On the other hand, Lalande had witnessed the latter part of the Venus transit from Paris and, as he put it, “I was not uncertain so much as a single second.”
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On the other side of the channel, Maskelyne took the widely varying solar parallax results as a sign of polluted data. “I'm afraid we must wait till the next transit in 1769,” Maskelyne reported to the Royal Society, “. . . to do justice to Dr. Halley's noble proposal and to settle, with the last and greatest degree of exactness, that curious and nice element in astronomy, the sun's parallax, and thence determine the true distance of all the planets from the sun and from each other.”
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The world would have to try again.

War was over.

England and Prussia had led a loose-knit coalition of allies to battlefield triumphs in North America, Europe, India, and western Africa—and to naval victories in the Atlantic, North Sea, Mediterranean, and Caribbean. “The flame of war,” one contemporary chronicler wrote, had been kindled “in every quarter of the world, and which afterwards raged . . . with a destructive and unrelenting fury, beyond the example of former times.”
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Spain, Portugal, and France had surrendered to Britain in February 1763, while at the same time Austria ratified a separate treaty with Prussia. Russia had withdrawn from the conflict due to monarchical intransigence, while “war's end” in North America meant sowing the seeds of bloody conflict for generations to come with indigenous tribes across the continent. In the age of Voltaire, lunar longitudes, and rococo, even peace was complicated.

King Louis XV of France was willing to accept all but one of the provisions of the Treaty of Paris, which ended the Seven Years' War: Britain
insisted that France level its towering coastal forts at Dunkirk. England feared that a heavily armed Dunkirk—from whose citadel one could practically see the mouth of the Thames—would be a perfect staging ground for French mischief. The French king brooded.
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Ultimately, having forfeited the perfect launching point for a military invasion of Britain, Louis began planning in secret for a military invasion of Britain. Heading up Louis's entourage of personal spies in England was a diplomat and soldier named Charles Geneviève Louis Auguste André Timothée d'Éon de Beaumont. D'Éon was a small and slippery man hiding behind a billboard of a name. His reputation for disguise was legend. Rumors circulated that only a few years before, d'Éon had penetrated Russian empress Elizabeth's inner circle in St. Petersburg by posing as one “Mademoiselle Lia de Beaumont,” a “niece” of a distinguished British tourist (who was also a French spy).
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In March 1763, King Louis had sent d'Éon to London to secretly scout out the English countryside for enemy troop garrisons and possible landing sites for a French strike force. The king kept nearly all of his advisers ignorant of the undercover mission. Louis would later write down d'Éon's sub-rosa orders, to make “reconnaissances . . . in England, be it on the coasts, be it in the interior of the country . . . [and to] keep this affair strictly secret and . . . never mention anything of it to any living person, not even to my ministers.”
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