AMERICAN PHILOSOPHICAL SOCIETY / SCIENCE PHOTO LIBRARY AMERICAN PHILOSOPHICAL SOCIETY / SCIENCE PHOTO LIBRARY
Diagram of the transit of Venus of the 3rd June 1769 as observed by the American astronomer David Rittenhouse (1732-1796) from Philadelphia, Pennsylvania, USA. This is the passage of the planet across the surface of the Sun as seen from Earth. Observations of the transit of 1769 from multiple locations allowed the distance between the Earth and the Sun (the astronomical unit, AU) to be calculated. The measurement obtained was within one per cent of today's measurement.
Model release not required. Property release not required.