Meteor Sounds

If a person hears sounds while observing a meteor's descent, these can be used to help pinpoint the location of the fall.

Single or multiple loud reports, like cannon fire, are sometimes heard a minute or two after the meteor is seen. Identical to sonic booms, these are caused by shock waves (zones of high air pressure) arriving at the observer's location. They are created high up along the meteor's path while it is still moving faster than the speed of sound in air. Unless the observer is almost exactly at the impact point, the shock wave detonations are the last thing to be heard. At that location, the observer will not see a streak as the meteor approaches, only a light that grows brighter and larger.

If an observer is near the projected impact point--the point where the meteor falls or would fall if it has not entirely burned up or broken up into tiny pieces that might scatter widely--sounds like thunder, a train rumbling over a viaduct or the tearing of cloth may be heard before the shock waves are heard. The tearing sounds arise near the end of the visible path of the meteor, usually only a few miles above the ground. These sounds are thought to be associated with the breaking up of the meteor, perhaps from thermal expansion due to rapid heating as the meteor plows through the dense air of the lower atmosphere.

People sometimes report a slight whistling, crackling or sizzling sound before hearing anything else, and usually while the meteor fireball is in sight. The cause of these noises is not known. Some authorities think the sounds are illusory even though the sensation of hearing them is genuine, the idea being that the sound may be a trick of the brain since human experience suggests that anything bright and fast-moving should whistle or sizzle.

Such sounds, first the sizzling, then the tearing and finally the cannon-like detonations., are heard if the observer is within 50 km (30 miles) or so of the impact point, except that the detonations are heard first if the observer is essentially at the impact point. There is a zone of quiet roughly 50 km to 100 km away; outside that region the shock waves may be heard. The zone of quiet is caused by refraction of sound waves in the lower atmosphere.