Next time you find yourself grousing when the passenger in front reclines his seat a smidgen too far, consider the astronomers of the Enlightenment. In 1761 and 1769, dozens and dozens of stargazers travelled thousands of miserable miles to observe a rare and awesome celestial phenomenon. They went by sailing ship and open dinghy, by carriage, by sledge and on foot. They endured discomfort that in our own flabby century would generate years of litigation. And they did it all for science: the men in powdered wigs and knee britches were determined to measure the transit of Venus.
That beautiful name, transit of Venus, describes the hours-long passage of our nearest planetary neighbour across the face of the sun. Transits occur in eight-year pairs followed by interludes of more than a century. Their rarity highlights the news hook for Andrea Wulf’s account of this ur-Big Science project: the next transit of Venus happens to be soon, on June 5 and 6, 2012. For a writer, that’s deadline pressure on a cosmic scale.
June’s transit will be a lovely spectacle, but it has little real scientific significance. When Wulf’s story begins, in the early 1700s, the situation was very different. The British astronomer Edmond Halley had realised that precise measurement of a transit might give astronomers armed with a clock and a telescope the data they needed to calculate how far Earth is from the Sun. With that distance in hand, they could work out the actual size of the solar system, the great astronomical problem of the era. The catch was that it would take multiple measurements from carefully chosen locations all over the Northern and Southern Hemispheres. But that was somebody else’s problem. Halley knew he wouldn’t live to see the transit of 1761.
That challenge fell to the French astronomer Joseph-Nicolas Delisle, who managed to energise and rally his colleagues in the years leading up to the transit, then co-ordinate the enormous effort that would ultimately involve scientists and adventurers from France, Britain, Russia, Germany, the Netherlands, Italy, Sweden and the American colonies. When you think about how hard it is to arrange a simple dinner with a few friends who live in the same city and use the same language when e-mailing, it’s enough to take your breath away.
And all this travel and data-sharing had to happen, Wulf notes, at a time when “a letter posted in Philadelphia took two to three months to reach London”. What’s more, standardised measurements were nonexistent. An English mile was different from a German mile; a Swedish mil was shorter than the Norwegian version. Don’t even start on France, where units of measurement varied from village to village, like wines or cheeses.
Sea travel was so risky in 1761 that observers took separate ships to the same destination to increase the chances some of them would make it alive. The Seven Years’ War was on, and getting caught in the cross-fire was a constant concern. One French scientist carried a passport arranged by the Royal Society in London advising the British military “not to molest his person or Effects upon any account”. Others were shelled by the French or caught in border troubles with the Russians. An observer en route to Tobolsk, in Siberia, found himself floating in ice up to his waist when his carriage fell through the frozen river they were travelling in lieu of a road. He made it to his destination.
Once the astronomers got to their destinations, their troubles really began. Dates with Venus are like outdoor weddings, except that in a pinch you can get married in the living room. If it’s cloudy or foggy during a transit, you’re out of luck. Perhaps the sorriest transit tale Wulf tells is that of the French observer who set off for Pondicherry, in southern India, a prime viewing spot. He dodged British warships on the way, but when nearly there learned that Pondicherry was under British siege. He wound up gamely trying to observe the transit from the pitching deck of a ship in the Indian Ocean, but clouds spoiled even that effort. A British observer spent months slogging around the mountains of St Helena looking for a vantage point not blocked “with Fogs & vapours” but on the day itself the hoped-for observation was impossible.
In a perfect world Chasing Venus would read like a Patrick O’Brian novel with references. Wulf gives it her best shot, but the sprawling narrative defeats her in the end. Even a writer as supple as she is can’t sustain momentum in a story with two climaxes — 1761 and 1769. It’s an impossible structure. There’s a huge cast of characters, each with a tale of his own, and it’s hard for a reader to keep them all straight. In sentences like “Nevil Maskelyne and his assistant left Britain for St Helena at the end of January 1761, just as Pingré’s ship sailed past Madeira and as Le Gentil was agonising about where to go to from Mauritius,” I could feel Wulf throwing me a lifeline. Despite her efforts, I just thought, “Which one was Pingré, again? And where is Mauritius?” That’s not to say that transit fanatics won’t find much to delight in here. But dabblers might do better to sit quietly during this year’s transit and simply watch the goddess’ stately progress, either in the sky or – wouldn’t Halley love it? – with the free smartphone app. Sic transit the glory of Venus.
CHASING VENUS
The Race to Measure the Heavens
Andrea Wulf
Alfred A Knopf; 304 pages; $26.95
©2012 The New York Times News Service