If you've been lucky enough to witness a meteor crash into Earth before, you may have noticed the booming, crackling sound that reverberates with it.
Indeed, these bright meteors streak through the atmosphere often accompanied by popping, sizzling, hissing, or rustling sounds.
What scientists find strange, however, is that if these flaring meteors are at least sixty miles away from onlookers, the sound they make should take at least a few minutes before being heard.
What causes the strange crackling sound then?
Crackling Meteor Sounds
That's what Richard Spalding and his team from Sandia National Laboratories in New Mexico sought to find out in a new study. After carefully testing objects that could produce sound, Spalding and his colleagues revealed that the crackling sounds may have been created through light.
The team's explanation is tied to a scientific principle called the "photoacoustic effect," which points to a process where materials absorb light energy and create sound waves.
Fireballs of meteor that break through the atmosphere sometimes pulse with light that is a hundred times brighter than any full moon, researchers said.
These fireballs briefly heat the surfaces of objects even from miles away. The sudden change in temperature can actually produce sound.
Spalding and his colleagues refer to the objects as natural "dielectric transducers," which are materials that can easily absorb light, heat up rapidly, and have low conductivity.
Scientists have previously suggested that meteors called "electrophonic meteors" emit levels of low frequency radio waves that produce instantaneous sounds.
Meanwhile, Spalding and his colleagues said that their explanation is more plausible compared to this, because it suggests that anyone can hear the sound of a meteor as long as it is bright enough and the sky-watchers are situated in a quiet area.
Light Creates Sounds
Dielectric transducers often include everyday objects such as leaves, dark paint, dark clothing, and grass. Meteor onlookers who are positioned near these objects are more likely hear the crackling sound of meteors.
Hair is another great example of a dielectric transducer. Past research has shown that people with fine or frizzy hair have higher chances of hearing meteors.
Spalding said this makes sense. "Hair near the ears will create localized sound pressure," he said.
What's more, hair holds enough surface-to-volume ratio that maximizes the creation of sound.
In 1880, Alexander Graham Bell observed the photoacoustic effect and applied the principle in his invention -- the photophone, a device that transmitted speech through light.
The findings of the new study are featured in the journal Scientific Reports. Watch the videos below.
