1769 Transit of Venus observed from Tahiti while voyaging to (unsuccessfully) observe the 1761 Transit in Sumatra. Using the solar parallax values obtained from the 1769 transit, Hornsby wrote in "Philosophical Transitions" December 1771 that "the mean distance from the Earth to the Sun (is) 93,726,900 English miles." The radar-based value used today for the astronomical unit is . This is only a difference of eight-tenths of one percent. Considering what these astronomers had to work with, their results were "absolutely remarkable". 1769 Transit of Venus observed from Tahiti On June 3, 1769, British navigator Captain James Cook, British naturalist Joseph Banks, British astronomer Charles Green and
Tahiti of Tautra, Matahiapo, chief of Teahupo'o, Tutea, chief of Vaira'o, and Moe, chief of Afa'Ahiti. In Papara, guided by Tupaia, they investigated the ruins of Mahaiatea marae, an impressive structure containing a stone pyramid or "ahu", measuring high, long and wide. Cook and "Endeavour" departed Tahiti on 13 July 1769, taking Raiatean navigator Tupaia along for his geographic knowledge of the islands. Cook estimated the population to be 200,000 including all the nearby islands in the chain. This estimate was later lowered to 35,000 by anthropologist Douglas L. Oliver, the foremost modern authority on Tahiti, at the time of first