The beginning of Armageddon, or an alien invasion? Over the weekend, people in the UK and parts of the US were awoken by loud, rumbling noises that were reportedly powerful enough to shake the glass of windows. It wasn’t long before alarmist hashtags, such as #omgwereallgoingtodie, began to appear on Twitter.

There’s no real need to panic, though; mysteriously loud noises have been reported for hundreds of years across the world. In Italian they are called “brontidi” (thunder-like); in Bangladesh they are “Barisal guns”. US citizens call them “skyquakes”, “moodus noises” and in North and South Carolina, “Seneca guns”. The writer Washington Irving even wrote a story about the mystery booms, which he playfully attributed to ghosts playing nine-pin bowling in the mountains.

But, what actually causes them?

There are many potential explanations, according to David Hill, a scientist at the US Geological Survey, who wrote a recent scientific review paper rounding up the causes of “mystery booms”. In coastal regions, for instance, large bangs may accompany humungous waves hitting the cliffs; reports of thunderous sounds are apparently common among big-wave surfers in the US.