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
1769 Transit of Venus observed from Tahiti the transit. The viewing of the 1761 transit involved the effort of 120 observers from nine nations. Thomas Hornsby reported the observations as unsuccessful primarily due to poor weather conditions. He alerted the Royal Society in 1766 that preparations needed to begin for the 1769 transit. Hornsby's publication in the "Philosophical Transactions of the Royal Society" in 1766 focused attention on the "cone of visibility" indicating, like Halley, some of the better places to observe the transit. The Royal Society boasted that the British "were inferior to no nation on earth, ancient or modern" and were eager to make another