The orbits of Venus and Earth around the Sun cause Venus to pass across the face of the Sun (as seen from the Earth) periodically. The pattern is: two transits eight years apart, then a pause for 121.5 years, then repeat. In the 18th century, astronomers were only just starting to apply Newton’s laws of physics to the solar system. Because they did not have an easy yardstick to measure, they used the transits of Venus in the later part of that century to establish a benchmark for their calculations of the distances between the planets and the Sun.
This book on the Krueger Library retention list discusses those adventurous astronomers who traveled the globe at that time to get measurements of the transit. The observations by David Rittenhouse in 1769 in Philadelphia made him famous within the American colonies. Because of that work, he was selected to be the first endowed Chair in Astronomy at the University of Pennsylvania.
Woolf, Harry. The Transits of Venus; a Study of Eighteenth-Century Science.Princeton, N.J: Princeton University Press, 1959.
Recap: In 2022, twenty-four Minnesota libraries joined together in a commitment to retain over a half-million print books which are scarcely-held in Minnesota. It is called the Minnesota Shared Print Collection. This is one of the stories from the Winona State share of the collection.
