Chasing Venus

During Venus's transit, observers can see the planet as a small black dot against the face of the sun. The transit is a rare event: while the last one occurred in June 2004 and the next will occur in June of this year, Venus will not appear again between Earth and the Sun until December 2117. Like Mark Anderson's The Day the World Discovered the Sun (reviewed above), Wulf's (Founding Gardeners: The Revolutionary Generation, Nature, and the Shaping of the American Nation) book is concerned with Venus's 1761 and 1769 transits, when the international science community dispatched a remarkable set of expeditions to remote parts of the world to observe and measure the planet's passages across the sun. Their primary objective was to use newly acquired observational data to improve knowledge of the distance between Earth and the Sun and the solar system's dimensions. Many of the traveling scientists underwent great travails, and several died.