For thousands of years, human beings have been looking up at the night sky in awe and wonder. What are those tiny points of light, and how far away are they? Does space go on forever? Did the universe have a beginning? The answers to all of these questions did not come until the twentieth century and hinged on determining the distance to the Sun. That key measurement was made in the eighteenth century, using the first very accurate clock, which measured the time it took for Venus to cross in front of the Sun. In this talk, astrophysicist and writer Alan Lightman will explain how a measurement of the “transit of Venus” allowed scientists to measure the distance to the Sun and, later, the size and evolution of the entire cosmos.

 Lightman is a physicist, novelist, professor of humanities at MIT, and summer resident in Harpswell. He writes frequently for the Harpswell Anchor.