I have to find venus and when its passing through the sun and the earth to heel astronomers calculate te distance from the sun to the earth
James cook went on his first journey on August 26,1768. His main goal was to was to observe Venus as it passed between the earth and the sun, This would help astronomers calculate the distance from the Sun to the Earth.
On his second mission his goal was to find the southern island or to prove that it wasn't here. He went below 70 degrees latitude which is the farthest any european at the time has traveled.