In a previous post, I tried to explain that some of the strange sounds around the world could be related to fireballs or/ and meteors exploding or just travelling in our atmosphere. Now it’s done! After 50 years of efforts, physicists have tuned in to the radio waves emitted by fireballs streaking through Earth’s atmosphere.
A meteor with a tail as bright, or brighter, than Venus is known as a fireball – the Chelyabinsk meteor is an example as it appeared brighter than the sun at its brightest. WOW!
Fireballs ionise nearby air as they barrel through Earth’s atmosphere, generating a super-bright plasma trail. In 1958, Gerald Hawkins, then at Boston University, predicted that this plasma should produce radio waves as it cools. But hunts for these radio emissions were inconclusive at best.
In a new paper published in The Astrophysical Journal Letters, a group of scientists from the University of New Mexico in Albuquerque have discovered these mysterious, low-frequency strange sounds (radio bursts) in data from the Long Wavelength Array.
Here an example of the Chelyabinsk meteor infrasounds recorded by the CTBTO’s International Monitoring System:
Here is their abstract:
We present the findings from the Prototype All-Sky Imager, a back end correlator of the first station of the Long Wavelength Array, which has recorded over 11,000 hr of all-sky images at frequencies between 25 and 75 MHz. In a search of this data for radio transients, we have found 49 long-duration (10 s of seconds) transients. Ten of these transients correlate both spatially and temporally with large meteors (fireballs), and their signatures suggest that fireballs emit a previously undiscovered low frequency, non-thermal pulse. This emission provides a new probe into the physics of meteors and identifies a new form of naturally occurring radio transient foreground.
The team still needs to work out the exact physical mechanism that causes fireballs to emit these specific low-frequency signals. Solving the puzzle could help improve our understanding of other mysterious events that create plasmas in Earth’s atmosphere, such as lightning strikes and ball lightning as explained by News Scientists.