Rare astronomical events provide some of the best opportunities to learn about the universe. In The Day the World Discovered the Sun, Mark Anderson describes how 18th-century astronomers used the passage of Venus across the face of the sun to estimate the distance from the Earth to the sun. Anderson modeled his book on the extremely popular Longitude and, in fact, covers some of the same territory.
Astronomers rarely work alone. The secret to accurate measurement is to have several teams attack a problem and compare their results. Also, because astronomical measurements are highly sensitive to the observers' locale and to weather, it makes sense to have several teams taking measurements from geographically dispersed posts. Throw in a serious bout of international competition and you set the stage for a fascinating story.
Travel in the 1760s was nothing like it is today. Ships relied on wind to fill their sails, so sea voyages were fully at the mercy of the weather. It's also easy to forget how difficult and dangerous it was to sail in the open ocean. To reach what is now California, researchers from continental Europe had to swing around South America, a trip that took many months. Also, because researchers needed to build their own observatories, they had to leave well in advance of the June 3, 1769 traversal date to be ready in time. Even a seemingly brief sojourn to Trondheim, Norway, required parties to follow treacherous paths across rugged countryside where fatal accidents could occur at any moment. Throw in journeys across the frozen wastelands of Siberia and to the tropical islands of Tahiti and Indonesia and you get a sense of the dangers involved in occupying the best vantage points to measure the transit of Venus.
Beyond the dangers of geography, the threat of disease and even the superstitions of the local populations made the ventures even more perilous. In one case, the Siberian natives in the village housing one team of observers suspected the scientists were planning a ritual to bring about the end times. The local ruler provided an armed guard to keep them safe. Another team settled into a location in Baja California that was ravaged by disease. Rather than move along to their primary location and risk arriving too late to make their measurements, the expedition leader chose to establish that observatory in the stricken village. Though they were able to capture the information they desired, the leader, and several members of the team, paid the price for his decision.
The Day the World Discovered the Sun is a good book, but it does improve as it goes along. Exposition is desperately hard to write, particularly when there are so many characters to introduce, so I sympathize with Anderson's plight. That said, especially at the beginning, he writes in an occasionally breathless style that at times approaches the tone of British darts commentators trying to inject artificial enthusiasm and excitement into what could be a dull event. There's no need to do so here and, after the action is well and truly under way, he reverts to a voice that captures the weight and adventure inherent in the missions without the need for rhetorical artifice.
I enjoyed Anderson's work and recommend The Day the World Discovered the Sun as both an adventure tale and a look back into the history of science. Then, as now, competition and cooperation play vital roles in discovering and verifying new information.
Curtis Frye is the editor of Technology and Society Book Reviews. He is the author of more than 30 books, most recently Improspectives; his list includes more than 20 books for Microsoft Press and O'Reilly Media. He has also created over a dozen online training courses for lynda.com. In addition to his writing, Curt is a keynote speaker and entertainer. You can find more information about him at www.curtisfrye.com.