A SONIC boom has woken people and shaken houses across parts of London and the northern Home Counties.
People tweeted that a loud “explosion” had woken them at about 04:20 GMT – with houses shaking and reports of police sirens straight after.
The noise was generated by two Royal Air Force Typhoons, which launched from Coningsby in Lincolnshire and intercepted an unresponsive aircraft.
The sonic boom was heard across London, Hertfordshire and Bedfordshire.
London’s Metropolitan Police subsequently confirmed the bang was the result of the RAF aircraft being cleared to go faster than the speed of sound.
RAF jets are only given permission to go supersonic in emergencies, usually when they are required to intercept another aircraft.
What causes a sonic boom?
When an aircraft approaches the speed of sound (768mph or 1,236km/h), the air in front of the nose of the plane builds up a pressure front because it has “nowhere to escape”, said Dr Jim Wild of Lancaster University.
A sonic boom happens when that air “escapes”, creating a ripple effect which can be heard on the ground as a loud thunderclap.
It can be heard over such a large area because it moves with the plane, rather like the wake on the bow of a ship spreading out behind the vessel.
Popularity: 2% [?]