People all around the world have recorded strange sounds coming from the sky. The unknown sound is best described as the sound of a trumpet.
Could this be just a global phenomenon or something that people should be worried about?
This sound was recorded in the United States, Canada, Germany, Hungary, the Czech Republic, Denmark, Sweden, England, Costa Rica, Ukraine and France.
Some explanations of these events were given by scientists and they include fracking, rock bursts, venting of high-pressure gas, atmospheric pressure or the natural background noise.
An official explanation still has to be made. Until then, any theory about the origin of these strange sounds is just guessing.
Some explanations provided by media include theories of tectonic plates grinding, atmospheric pressure, trains shunting, construction, alien activity, HAARP weapon, the Apocalypse and the Seven Trumpets of Heaven.
According to NASA, this noise is simply a background noise of the Earth.