The date was predicted by English astronomer Edmund Halley more than seventy years before the phenomenon. He urged his colleagues to observe this phenomenon from different points of the globe and thus calculate the distance from the Earth to the Sun. Colleagues took the call and went to different points of the Earth – as far as the island of Tahiti, where Venus was observed against the background of the Sun by James Cook’s expedition en route to Australia which was, as it turned out, its true goal.
But let’s get back to the world scientific project – it was a success. The obtained dataset enabled calculation of the distance from the Earth to the Sun with a margin of 2 to 3 percent – incredibly accurate for the times. Unscrupulous popularizers of science write Lomonosov discovered Venusian atmosphere at the same time. Don’t believe it – it happened eight years earlier albeit also in June.