Possible Impact Phenomena (PIPs)
This chapter presents a catalog of documented events on the Moon likely (or possibly) resembling impact phenomena. These events are referred to by the author as possible impact phenomena (PIPs).The catalog was assembled from several different sources, listed later, and is divided into sections by century, beginning with the twelfth century. Naturally as one approaches the present day, the number of reported events seems to rise exponentially as the number of observers, as well as the efficiency of the methods of observations, increases. For example, in the entire seventeenth century, two events were recorded compared with 19 during the 1950s.