THE DAY THE WORLD DISCOVERED THE SUN   

By Mark Anderson.

DaCapo Press. 288

Reviewed by A. Sidney Barritt

A. SIDNEY BARRITT is a Roanoke physician.

On June 3, 1769, Venus would pass directly across the face of the sun. Mathematicians had learned in theory how to use Venus’ passage to triangulate the distance from Earth to the sun.

That would be a neat mathematical trick that could provide some interesting knowledge. For the theologically inclined, it would reveal the Creator’s plan as set forth in Genesis. For astronomers, it would advance pure science significantly akin to the modern launch of the Hubble telescope. And, for government and business, it could refine methods of determining longitude at sea; while latitude could be readily calculated, longitude could not and that had led to disasters where too many ships along with their crew and cargo had been lost.

Many astronomers, both amateur and professional, prepared to make measurements of the Venus passage. Here, author Mark Anderson chronicles the impressive journeys of three notable figures whose efforts dwarf the many others. Jean-Baptiste Chappe d’Auteroche, a prominent French astronomer, had previously gone to Siberia to witness the passage of 1761. This time, he sailed to Veracruz, Mexico, trudged across Central America, then sailed to Baja California. He contracted typhus, aka “jail fever,” and died but not before recording his sightings to the minute and second and seeing that the data were relayed back to Paris.

Two Jesuit priests, Maximillian Hell and Janos Sajnovics, headed to arctic Norway and spent a winter in the dark so as to have their instruments ready in time.

And, finally, in the best known of these journeys, Lieutenant James Cook, captain of His Majesty’s bark, the Endeavor, sailed around Cape Horn to Tahiti, where he and his staff make similar observations of Venus’ passage.

Not too surprisingly, some of the crew had a different sort of adventure while there and, when the circumnavigation was complete, presented their physicians at home with interesting varieties of sexually transmitted diseases.

All the data were eventually collated. Read the book’s epilogue for a good sense of all the spinoffs from what might be called Big Science from 250 years ago. The measurements were remarkably precise. The author suggests with good reason that NASA’s Apollo program from the 1960s and 1970s would be a good modern comparison.

Read it mainly, though, for an armchair travel adventure. One need not understand the math involved, although it is provided in an appendix.

And, if you have even the least interest in astronomy, note that the next passage of Venus will be June 5 and 6, 2012.