observe Venus as it passed between the Earth and the
Sun.
Precise measurements of this event were needed worldwide in order to calculate a distance between the Earth and the Sun.
During this expedition, he sailed from Plymouth, England, to Brazil, around Cape Horn (the southern tip of South America), and to Tahiti, where he stayed for months in order to observe the transit of Venus .
Then he mapped New Zealand and the east coast of Australia (known as New Holland at the time).
In October, 1770 Cook reached Batavia, Java, where about 30 members of the crew died from malaria (a disease carried by mosquitos).
On July 13, 1771, the Endeavor returned to England after a journey of almost three years.
The First Voyage (1768–1771)