As the 2012 transit of Venus rolled around, I got caught up in the excitement. Which led me to read The Day the World Discovered the Sun, a new account of the arduous attempts by the scientific community to observe the two Venus transits of the 1760s. (My ensuing audio interviews with author Mark Anderson are archived at

Until I read the book, I never knew how much I had in common with 18th-century French astronomer Jean-Baptiste Chappe d'Auteroche. Well, we had one big thing in common. In 1769 he traveled to the Sea of Cortez, between the Baja peninsula and mainland Mexico, to observe the transit. His data collection, combined with those of other sky watchers at different latitudes, would enable astronomers to calculate the distance from Earth to Venus and the sun. In 1991 I went to the same location, which lay in the narrow band that would experience another spectacular astronomical event, a total eclipse of the sun.

Let's compare the two journeys.

In September 1768 Chappe sails from France to Spain, schlepping enough equipment to construct an observatory in his ultimate destination, Cabo San Lucas, which won't be a hopping resort town for another two centuries. On July 4, 1991, I leave New York City on a train for Los Angeles with a couple of astronomically interested friends—we figured we'd see the country along the way from our sleeper cars. I pack a couple of Hawaiian shirts.

It takes Chappe three weeks to get to Cádiz. Twenty hours after leaving New York, my amigos and I arrive in Chicago, where we're forced to change trains and endure a six-hour layover. Fortunately, there's a food fair along the lakeshore.

In December 1768 Chappe begins a 77-day transatlantic voyage onboard what he called “our little nutshell.” On July 5, 1991, my group leaves Chicago on a double-decker superliner train for L.A.

On March 6, 1769, Chappe's ship sets anchor near Veracruz. The vessel sits there for two days before local officials send a skiff to bring Chappe to shore. A hurricane almost destroys the anchored ship and its cache of astronomical equipment. Two days after leaving Chicago, my team pulls into the City of Angels, having taken in a lovely traverse of the Colorado River from the observation car. We head to a nice hotel.

In mid-March, Chappe begins traveling over land to the Pacific side of Mexico, which he will reach on April 15. On July 7, 1991, my buddies and I find a decent Mexican restaurant for dinner.

On April 19, 1769, Chappe sets sail onboard a small vessel called La Concepción. Unfriendly currents and winds keep him and his mates at sea for a full month before they reach Baja. On July 8, 1991, my friends and I leave the Port of Los Angeles onboard the cruise ship Viking Serenade. Built in 1982, it had been the world's largest cruise ferry and was later converted into a luxury cruise ship. Other passengers include moon-walking astronaut Harrison Schmitt and amateur astronomer John Astin, television's Gomez Addams. Me and the boys rough it in our windowless interior cabin.

For a week and a half in late May 1769, Chappe and his crew build their observatory in San José del Cabo. For three days onboard the cruise ship, as it sails down Baja and up into the Sea of Cortez, my crew attends astronomy lectures, plays Ping-Pong under bright blue skies on the top deck, and eats from dawn till the midnight buffet.

On June 3, 1769, Chappe lucks out—perhaps his first and last brush with good fortune on this journey—and gets a clear day to make his observations of the Venus transit. His data will help scientists determine the dimensions of the solar system. On July 11, 1991, an overcast sky threatens our eclipse watching. But using satellite weather images, the captain speeds to a cloudless spot, where we observe six minutes and 53 seconds of totality, just 38 seconds less than the theoretical maximum. It's very cool.

Following the transit, Chappe and many of his men fall victim to a typhus epidemic. Following the eclipse, we set sail back to L.A. Rough seas make me a bit queasy.

On August 1, 1769, Chappe passes away. Among his last words: “I have fulfilled my purpose, and I die happy.” On July 14, 1991, my friends and I arrive back in Los Angeles and head to the train station. Among our last words there before another three-day train trip: “Maybe we should have flown.”

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