Letter from Thomas Gold to Verl R Wilmarth, Chief of Lunar Physics, Apollo Lunar Exploration Office, NASA Headquarters, Washington, DC Reporting on the Surveyor bright horizon investigation. Says that 'The purpose of the proposed investigation is to obtain a better understanding of the real distribution of light that must have occurred to cause the bright horizon seen in Surveyor pictures taken after sunset. This information is needed to gain an understanding of the phenomenon'. Goes on to discuss the proposed investigation in detail. 22 July 1968