The book Sidereus Nuncius, or Starry Messenger was published by Galileo Galilei in March 1610. In it he records his first views of the heavens through a telescope. This is one of the great scientific publications that changed the world. Galileo’s excitement is palpable as he describes the craters on the moon, a myriad of countless stars and his discovery of the four orbiting moons of Jupiter.
Prior to this time, people could view the night sky only with their unaided eyes. They thought the moon’s surface was smooth and perfect. He was first to describe craters and correctly deduce the mountains, valleys and “seas” of the moon. Likewise the night sky appears to have only a fixed number of stars. But with a telescope these were resolved into countless numbers of individual stars.
When he turned his telescope towards Jupiter, he was amazed to find four tiny “stars” that revolved around the planet. I will never forget when as a youngster, I turned my new telescope toward Jupiter. Upon seeing the four moons, I experienced that same magical excitement that Galileo could hardly contain in his writing. I stared transfixed by the sight, almost wanting to see those satellites move. They do move of course, but it takes a few hours to notice any appreciable change in position.
Galileo first looked at Jupiter on January 7, 1610. Merely three months later he had published his book Sidereus Nuncius. It’s an amazingly short period of time to make these observations, come up with theories about what he saw and make detailed measurements and drawings. Again it shows his excitement and motivation to make these discoveries known to the world.
I have an interest in computational astronomy. It is fun to plot the relative positions of Jupiter’s satellites with a computer program. I can recreate their positions as they appeared on those nights in 1610. It’s exciting to see they match Galileo’s sketches. It’s a connection to the past, and a way of sharing the excitement of a great moment in history.
Digitized images of the original publication are available at the Linda Hall Library: http://www.lindahall.org/services/digital/index.shtml. You can view the illustrations, which presumably are woodcuts based on Galileo’s original drawings.
Edward Stafford Carlos published an English translation of the work in 1880. It’s available to view at Google Books: http://books.google.com/books?id=IDQDAAAAQAAJ