Galileo Galilei’s First Drawings of the Moon After Seeing It Through the Telescope in 1609

Galileo produced this extremely famous set of six watercolors of the Moon in its various phases “from life,” as he observed the Earth’s satellite through a telescope in the autumn of 1609. They represent the first realistic depiction of the Moon in history.

Until Galileo’s observations, the Moon was widely believed to be a smooth, perfect sphere, as Aristotle had posited. Galileo’s drawings, which showed a rugged, uneven surface with craters and mountains, challenged this orthodox view and contributed to the downfall of the Aristotelian cosmology.

His drawings of the Moon are remarkably accurate, given the limitations of his telescope. He observed the Moon over several nights in December 1609 and January 1610, and his drawings accurately depict the changes in the Moon’s appearance over this period.

Here are Galileo’s own words after observing the surface of the moon:

“Let me speak first of the surface of the Moon, which is turned towards us. For the sake of being understood more easily, I distinguish two parts in it, which I call respectively the brighter and the darker. The brighter part seems to surround and pervade the whole hemisphere; but the darker part, like a sort of cloud, discolors the Moon's surface and makes it appear covered with spots. These spots have never been observed by anyone before me; and from my observations of them, often repeated, I have been led to that opinion which I have expressed, namely, that I feel sure that the surface of the Moon is not perfectly smooth, free from inequalities and exactly spherical, as a large school of philosophers considers with regard to the Moon and the other heavenly bodies, but that, on the contrary, it is full of inequalities, uneven, full of hollows and protuberances, just like the surface of the Earth itself, which is varied everywhere by lofty mountains and deep valleys.”

He goes on to discuss his observations of the Milky Way:

“The next object which I have observed is the essence or substance of the Milky Way. By the aid of a telescope, anyone may behold this in a manner which so distinctly appeals to the senses that all the disputes which have tormented philosophers through so many ages are exploded at once by the irrefragable evidence of our eyes, and we are freed from wordy disputes upon this subject, for the Galaxy is nothing else but a mass of innumerable stars planted together in clusters. Upon whatever part of it you direct the telescope straightway a vast crowd of stars presents itself to view; many of them are tolerably large and extremely bright, but the number of small ones is quite beyond determination.”

Italian nobles were intrigued by the refined telescope, but the Catholic Church was less than pleased by the knowledge that came with it. Among these unfortunate realizations was that the Earth revolved around the Sun. The Galileo affair of the 17th century was a pivotal moment in Catholic Church history, setting the scene for both clashes and collaborations between science and religion. Galileo was both a heretic and a scientific legend. His drawings of the Moon, and other observations of the solar system, expanded the boundaries of human knowledge.