The Day the World Discovered the Sun by Mark Anderson

Pondicherry. So without a place to land, Le Gentil spent June 6, 1761, floating somewhere in the Indian Ocean—unable to set up a telescope onboard his swaying ship to observe Venus traversing the face of the sun. Le Gentil had ventured halfway across the globe, in other words, for nothing.
    With less than a month to go before the 1769 Venus transit, Chappe lay adrift in his own watery purgatory, recording in his journal increasingly anxious entries about the “calms and currents” on the Gulf of California. He had, in fact, only received what he had been told to expect.
    On April 15, upon arriving in San Blas, Chappe grew nervous that he might not make his Baja destination in time. The Californian gulf was well known for its quiet calm. The captain of Chappe’s new packet boat, La Concepcíon , said his last crossing of the deceptively narrow three-hundred-mile passage took twenty-one days. And that was at a better time of the year for favorable winds. So Chappe and his fellow Spanish astronomers weighed a last-minute alternative—setting up their observatory in San Blas and observing the Venus transit from there.
    But local officials in San Blas informed the travelers that the wet season was fast approaching. Steady rains usually arrived in late May and remained hunkered over this New Spanish Pacific port town for the ensuing month. The nearby Tres Marías islands, seventy-five miles offshore, offered no better prospects for clear skies on June 3 either.
    So the voyagers decided to risk it. Setting sail on April 19, the packet boat spent the next fifteen days trying in vain to fight contrary winds and currents. From May 4 to May 9, a breeze at last carried them northward along the shoreline to the latitude of their Baja destination. But they still had another two hundred miles of longitude yet to go. They still needed to actually cross the gulf.
    With just twenty-five days remaining before the century’s final Venus transit—during which time Chappe and his crew would also require at least a week to set up their instruments and observatory—eyes looked westward. And hearts sank. Even if La Concepcíon had picked up her pace to the rate the captain had reported on her previous crossing, they’d still not make it in time.
    The ship’s captain, no doubt in a gesture intended to placate the founder of the recently expelled Jesuits, set up a shrine on La Concepcíon to St. Francis Xavier. The captain, Chappe wrote, “laid [an offering] upon the binacle, beseeching him to send us a fair wind. The devout pilot’s remedy did not presently take effect, for the following days we had a succession of calms and contrary winds.”
    The boat continued to sail farther north, beyond the latitude of its destination, hoping to find a more generous current to cross the gulf. “From this time, it was my fixed resolution to land at the first place we could reach in California,” Chappe recorded. “I little cared whether it was inhabited or desert, so [long] as I could but make my observation.”
    By nightfall on May 18, some “favorable gales,” in Chappe’s words, had brought La Concepcíon —almost miraculously—to within twenty miles of Baja peninsular land. The captain surmised they were approaching San José del Cabo, a small town near the peninsula’s southern tip. The Spanish officers knew, however, that San José del Cabo would be a difficult landing. Heading toward this patch of Baja, they argued, risked wrecking the whole ship. “I was strenuous for landing at the nearest place,” Chappe recalled. “But as I was singular in my opinion thewhole day was spent in altercations. . . . I was confident that his Catholic Majesty had rather lose a poor pitiful vessel than the fruits of so important an expedition as ours.”
    Doz, Medina, and the captain argued for traveling a little farther down the coast, to more accommodating