Hevelius’ engraving of a full Moon. Image source: Hevelius, Johannes. Selenographia: sive, Lunae descriptio. Gdansk: Autoris sumtibus, 1647. View Source

Johannes Hevelius

Polish astronomer Johannes Hevelius began telescopic observations of the Moon in 1643 with a telescope that he made. Hevelius published his observations in his 1647 book, Selenographia. The treatise includes three large, detailed lunar maps (one of which is on display in the adjacent case) and 40 engravings of the Moon in various phases

Detailed illustration of Hipparchus Crater. Hooke performed tests to determine how the Moon’s craters had formed. He dropped bullets into wet clay to simulate an impact and watched bursting water vapor bubbles in boiling alabaster to simulate volcanic activity. Based on these experiments, he theorized that volcanism created the craters. Image source: Hooke, Robert (1635-1703). Micrographia. London: Printed by Jo. Martyn and Ja. Allestry, 1665. 

Robert Hooke

Robert Hooke’s Micrographia, published in 1665, is best known for its wonderfully detailed illustrations of insects and other objects that he had viewed under a microscope. Hevelius also included one illustration of the Moon in his book, a close-up view of lunar crater, Hipparchus, based on his observations with a 30-foot refractor telescope. It was the first detailed illustration of a specific lunar feature.

Cassini’s 1692 map. The 40 numbered sites were arranged in the order they would be eclipsed. Image source: Keill, John. Institutions astronomiques. Paris: Chez Hippolyte-Louis Guerin, & Jacques Guerin, 1746. 

Giovanni Cassini

Giovanni Cassini produced his first lunar map in 1679 based on his observations at the Paris Observatory. Very few copies were made of the large map, but a smaller version was first published in 1692 in advance of a total eclipse of the Moon. Forty sites on the Moon were numbered so that observers, in an attempt to determine longitude values at their locations, could track the timing of the eclipse as the Earth’s shadow passed over the lunar landscape.