With the formulation of Kepler’s third law at the beginning of the 17th century it became possible for astronomers to determine the distances between Earth, Venus and the Sun by employing the parallax method to precise observations of Venus moving across the solar disc. Since that time every “transit” of Venus except the last two in 2004 and 2012 was used to determine the distance of the Sun-Earth.
Although now superseded by modern measurement techniques, this old method is still a very instructive way of understanding the orbital movements of the inner planets in our solar system.
The images taken during the two expeditions to Svalbard and Australia to observe the transit of Venus on 2012-06-06 can be used to determine the distances of Earth, Venus and the Sun.
Michel G. Breitfellner