What's a 'sonic boom'?published at 09:29 British Summer Time 14 July 2016
Alex Pope
BBC Local Live
A sonic boom is created as an aircraft breaks the sound barrier, causing a high-energy shockwave.
When an aircraft approaches the speed of sound, the air in front of the nose builds up a pressure front because it has "nowhere to escape", Dr Jim Wild of Lancaster University said.
It can be heard over a large area because "it moves with the plane", similar to the wake on the bow of a ship spreading out behind the vessel, Dr Wild added.