Galileo’s Sidereus Nuncius (Starry Message)

The publication of Galileo’s Sidereus Nuncius in March 1610 was perhaps the single most unexpected event in the Scientific Revolution of the sixteenth and seventeenth centuries. The astronomical observations reported, made possible with the use of the recently invented telescope, were entirely unanticipated and arresting in their impact.

Sidereus Nuncius includes the results of Galileo's early observations of the Moon, hundreds of stars that cannot be seen with the naked eye, and the moons of Jupiter. He was the first person to deduce that the irregularities of light and dark seen on the surface of the Moon are shadows caused by low regions (craters) and by mountains.

Also astonishing is the fact that Sidereus Nuncius was prepared and printed very rapidly, during a period of just over six weeks in the spring of 1610, a record for any scientific book of the time. Galileo rushed to get his exciting findings into print and hired his own woodblock cutters for the illustrations (who apparently worked directly from his sketches) and a printer to put the illustrations and text together as a small and inexpensive news pamphlet. Parts of the text were being set into type at the printshop while Galileo was still working on additional observations and sketches. In this way, he retained full authorial control over the content and was also able to make his findings known to the scientific community without delay and, as he explained in a letter, before running “…the risk that perhaps someone else might have discovered the same and preceded me.”

The Moon illustration woodcut prints seen here are part of a later printing of Sidereus Nuncius in an astronomy textbook published in London in 1653, about a decade after Galileo’s death. Even though these illustrations were printed from a different set of woodblocks and are therefore one more step removed from Galileo’s original sketches (and are less detailed), they give us a glimpse of this remarkable moment in the history of science.

Source: Gingerich & Van Helden, “From Occhiale to Printed Page: The Making of Galileo’s Sidereus nuncius,” Journal for the History of Astronomy XXXIV (2003)