The mystery of hissing meteors

Has the reported phenomenon of 'hissing' meteors finally been explained?

The late Richard Spalding, who led the study, looks up at the night sky.
Credit: Photo by Randy Montoya

The late Richard Spalding, who led the study, looks up at the night sky © Randy Montoy

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Scientists studying the phenomenon of ‘hissing’ meteors believe they may have arrived at an explanation of the strange occurrence.

For centuries, observers of meteors entering Earth’s atmosphere have claimed to hear an accompanying hissing or rustling sound.

But if these odd sounds are indeed something more than just the psychological effect of the spectacle on the observer, how can we explain the apparent contradiction created by the fact that sound travels slower than light?

Surely, if the sound is coming from the meteor itself, the sound should be heard some time after the meteor’s appearance.

A new study suggests that the sounds associated with the arrival of a meteor could actually be caused by the light generated as the rock burns up in Earth’s atmosphere.

The late Sandia National Laboratories researcher Richard Spalding looked into the issue and concluded that the intense light from the meteor could be heating the surface of objects on Earth, which in turn heats the surrounding air.

This, the study reasons, could create the hissing sounds often reported by observers of meteors.

The team behind the study selected objects like leaves, grass, dark paint and hair, as these have low conductivity.

They exposed these to intense light, similar to the light that would be generated by a meteor, and found that they could rapidly warm and transmit heat energy into the air, generating pressure waves that can create sounds.

The sounds heard during meteor spotting “must be associated with some form of electromagnetic energy generated by the meteor, propagated to the vicinity of the observer and transduced into acoustic waves,” the study says.

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“A succession of light-pulse-produced pressure waves can then manifest as sound to a nearby observer.”