An American satellite orbiting above known as Vela Hotel 6911 detected a bright double flash of light below that seemed to be indicative of a nuclear explosion.
You need some loose fold of tissue to make that rapid trilling, and there's just no flesh loose enough to bounce around right at the back of the roof of your mouth, at what's called the velum.
Fearful the Soviets might try to test anyway — perhaps blowing up nukes on the far side of the Moon, where they couldn't be detected — the US launched a series of satellites called Vela.
There are journalists who claim that every successive US administration since then has deliberately covered up the truth of what the Vela incident actually was.
However, after going through the data, this panel curiously came to the conclusion that the Vela incident as was getting to be known was most likely caused by a natural event.
But in a way that's kind of what makes the Vela incident and other mysteries so interesting, the fact that you don't know all of the answers and the possibility that one day you might.