The Society was eager to have a record of the 1769 transit of Venus. This is a rare solar event, occurring every 120 years, during which the planet Venus crosses in front of the sun. The event comes in pairs 8 years apart. By noting the start and stop times of the transit from widely spaced locations on Earth, English astronomer Edmund Halley reasoned that scientists could calculate the distance to Venus using the principles of parallax. From these measurements, Halley hypothesised that scientists could then measure the scale of the solar system.

From the Society’s point of view, one of the most important passengers on the Endeavour voyage was 34-year-old Charles Green, astronomer, mathematician and chief observer of the transit.

The 35-year-old botanist Daniel Solander and wealthy 24-year-old Joseph Banks also applied together for a passage on board the Endeavour, and this application was received with great enthusiasm and support from King George III. As a result, Banks boarded the Endeavour with an extensive party (paid for out of his own pocket) that included himself, Solander, artist Sydney Parkinson, the naturalist Herman Spöring, four servants to assist in collecting specimens, and two dogs.

Cook and his crew arrived in Tahiti almost two months before the transit. In the intervening weeks, Cook and his crew set up their equipment in various locations around the island. They also documented the flora and fauna of Tahiti and the customs of the Tahitian locals.