The Moon

Gassendi, Pierre (1592–1655)
Institutio astronomica : juxta hypotheses tam veterum quàm recentiorum
; cui accesserunt Galileo Galilei Nuntius siderius, et Johannis Kepleri
Dioptrice
Londini: Jacobi Flesher, 1653.

This single volume contains three astronomical treatises: Pierre Gassendi’s Institutio astronomica, Galileo Galilei’s Sidereus Nuncius, and Johannes Kepler’s Dioptrice. Shown here are illustrations of the moon from Galileo’s groundbreaking work.
After hearing of an invention from the Netherlands that could make faraway objects appear much closer, Galileo created his telescope in Venice in 1609. He used this telescope to undertake the first systematic study of celestial objects, publishing Sidereus Nuncius, or the “starry messenger” in 1610. This copy is a third edition, published in 1653.
For the first time, the surface of the moon was observed to be mountainous and uneven rather than perfectly smooth and spherical, as was previously thought. Galileo also recorded four moons orbiting Jupiter, an observation which convinced him of the validity of Copernican heliocentrism.