reply to post by AlphaX
SKY SOUNDS is an interesting subject with many possible reasons for them. There are some VERY High Tech. U.S.A.F. Recon aircraft that have been
postulated to be using a Nuclear Micro-Detonation Propulsion of which there has been sighted from I believe...Google Earth...a line of Puffs of Smoke
beginning at Groom Lake and crossing the U.S. then crossing the Atlantic then across Europe, the Middle East then over China...over the Pacific and
back to Area 51.
This happened VERY FAST to allow documentation of the trails as well as it being able to circle the Globe without refueling which makes sense for a
Nuclear Powered Recon. Aircraft.
Other sounds might be the Earth itself. There is much here to look into.