Sonic boom
A sonic boom is the thunder-like bang made by a meteoroid moving faster than sound through the air.
Sound travels through air at roughly 340 metres per second near the ground. A meteoroid enters at many kilometres per second, so it is far faster than sound. Like a supersonic jet, it pushes the air into a cone-shaped shock wave, and when that wave reaches the ground people hear a sonic boom: a sharp bang, rumbling like distant thunder or gunfire.
Because sound is slow, the boom arrives well after the light. A meteor glowing 30 kilometres up takes about a minute and a half for its sound to reach you, so people often hear booms a minute or more after seeing the flash. Breakups along the path can add extra bangs and crackles. During the Chelyabinsk airburst in 2013, the shock wave arrived over a minute after the flash and shattered windows across the city.
Booms are an encouraging sign for meteorite hunters. They mean the object penetrated deep into the atmosphere, so pieces may have survived to land. Some witnesses also report hearing hissing at the same moment as the light, a puzzling effect still being studied.
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Level: Explorer Ages 10 and up