Alien conspiracy theorists are convinced there is more than meets the eye at Area 51.
A video showing the strange noises over the Nevada US Air Force base posted on YouTube by channel UFO Seekers has racked up more than 40,000 hits already.
In the clip, F-22 fighter jets can be seen flying over the infamous airspace.
The stealth planes leave strange trails as they cut through the Nevada skies at speeds of up to 1,500mph, Dailystar.co.uk reports.
Then, as one accelerates away, a frighteningly loud double booming sound can be heard.
These fighter jets are a distraction from the real testing within the site.
It is claimed that alien flying saucers crashed on Earth, such as the alleged 1947 Roswell incident, andThis post was originally published on this site