What sound do meteors make? It might sound like a stupid question, but it’s actually rather surprising – and equally interesting, too.
The answer is that a meteor burning up in our atmosphere can produce the sound of rustling leaves or faint whispers to observers on the ground. The reason is due to the bright light produced as it burns up.
As explained in a recent article in Scientific Reports, led by Sandia National Laboratories in New Mexico, the process is known as photoacoustic coupling. When the meteor produces a bright light, lasting up to two seconds or more, the pulses of light can heat the surfaces of things on the ground, such as leaves, grass, dark paint, and even your hair.
“The surfaces rapidly warm and conduct heat into the nearby air, generating pressure waves,” the article notes. “A succession of light-pulse-produced pressure waves can then manifest as sound to a nearby observer.”
Alexander Graham Bell first noticed the effect back in 1888, observing how sunlight produced sounds when impacting on a variety of materials. Other research has picked up on this effect before.
This explanation helps to solve a conundrum about meteors, namely how they can be accompanied by a soft hissing sound, but well before sound waves from the event should have reached us.
“The photoacoustic hypothesis provides an alternative explanation for this longstanding mystery about generation of concurrent sounds by fireballs,” the authors of the article wrote.
In their experiments, the authors used a variety of materials to come to their conclusion, including a brown wig, dark cloth, and wood. The wig was found to produce a sound at about 40 decibels when hit by light of a specific frequency, which is slightly more than a whisper (30 decibels) and rustling leaves (20 decibels).
There are other factors that will affect whether you hear a meteor or not, though. These include being in a quiet environment, the brightness of the meteor, and the frequency of the light it emits.
But if everything is in your favor, the next time you see a meteor, it might – just might – be accompanied by a small whisper.