In the Starry Messenger (1610), Galileo published the first observations of the heavens made with the telescope. His report caused a sensation, as he claimed to discover mountains on the Moon, vast numbers of previously undetected stars and four satellites of Jupiter. The planet Jupiter moves through the heavens without leaving its satellites behind. The Earth and Moon both have mountains, seas, atmospheres, and both shine by reflected light. All of these discoveries might suggest that the Earth is also a wandering planet.

When Galileo peered look through his telescope and discovered mountains on the Moon, he did so because he was seeing with the eyes of an artist. Contemporaries without artistic training were not able to see what Galileo saw. His training as an artist allowed him to perceive light and shadow in a way other astronomers could not.

Galileo’s Starry Messenger (1610) set off the 17th-century race for the Moon – not a race to for flight, but a race to map its surface. To stare directly at the Full Moon is blinding at night; surface detail is entirely washed out, thus, to map the Moon, one must examine the “shadow line” night by night as it passes across the face of the Moon.  Light moves back and forth, first one way and then the other, casting shadows in both directions at opposite phases.  The lunar map gradually emerges as a composite representation of many individual topographical studies.

The wonder of the sky at night is common to science and to art. From the Renaissance to the dawn of the modern age, art and science fuse together in the representation of the stars and constellations. These star maps combined state-of-the-art scientific observation of the cosmos with artistic and cultural representations of the sky at night.