Letter from Thomas Gold to Dr S Keith Runcorn, Head, School of Physics, University of Newcastle upon Tyne, Newcastle upon Tyne, England Covering letter accepting invitation to give a talk at the Joint Discussion on 'The Origin of the Moon and Satellites' sponsored by Commisions 16 and 17 of the General Assembly of the I.A.U. in Sydney, with the title of 'The Formation of the Moon as a Secondary Accumulation Process'. Abstract enclosed 27 February 1973