The Observation of Lunar Impacts
  The intense activity of cratering on the Moon and in the inner regions of the solar system was accomplished during the first 10^9 years [1]. Occasionally, some impact events occur even nowadays. In Section 1, we treat, from a historical point of view, the Earth-based observation of lunar impacts. In Section 2, we consider the visibility conditions of such events evaluating the luminosity of the background upon which an impact shines. In Section~3, the luminosity of an impact is discussed. The occurrence of lunar impact events outside of meteor shower periods is calculated using the hourly rate of the sporadic meteors and their population index. The evidence of a larger rate of impacts of meteoroids in the past under these hypotheses is presentend in the last section. 
Giovanni Imponente and Costantino Sigismondi