1) Astronomical hypothesis 
Moongate can refer to several things: Books Video Games ...[book] Moongate: Suppressed Findings of the U.S. Space Program, The NASA-Military Cover-Up is a self-published book by William L. Brian II which alleges a cover-up by NASA, the United States Armed Forces and the Russian space program over what was really found during the US and Soviet Moon landings and space programs in general. Brian, a nu...