Moon Struck . ... Credit Copyright: David Palmer ( LANL ) Explanation: Craters produced by ancient impacts on the airless Moon have long been a familiar sight . But only since 1999 have observers seen elusive optical flashes on the lunar surface - likely explosions resulting from impacting meteoroids. ... Six confirmed flashes, some initially as bright as a third magnitude star, were all seen within hours of the peak of the 1999 shower. ... NASA Web Site Statements, Warnings, and Disclaimers . ...