After 50 years of trying, 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 that broke apart over Russia early last year is an example. At its brightest, the Chelyabinsk fireball appeared brighter than the sun.
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.
Now we know that Hawkins was right. Kenneth Obenberger at the University of New Mexico in Albuquerque and his colleagues were searching for mysterious events called radio bursts in data from the
Long Wavelength Array, an observatory in New Mexico. Radio bursts show up as points of radiation in images. But to the team's surprise, analysis of 11,000 hours of data included evidence of 10 low-frequency radio bursts that appeared smudged across the sky.
Meteor radioThe shapes of the smudges were reminiscent of fireballs streaming through the sky. So the team looked at data from a NASA survey telescope that records meteors and that scans some of the same parts of the sky as the radio array. Each of the elongated radio events correlated in time and space with known fireballs, says Obenberger.
"It's the first detection that is believable because it's based on imaging," says
Peter Jenniskens at the SETI Institute and NASA Ames Research Center in California's Silicon Valley. "It's a new way of looking at meteors."
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, says David Meisel, executive director of the American Meteor Society in Geneseo, New York.
Journal reference:
The Astrophysical Journal Letters,
DOI: 10.1088/2041-8205/788/2/L26
Comment: The Obenberger team and New Scientist seem to be behind times, perhaps this stems from being loyal to mainstream models?
The plasma tails of certain meteors do become turbulent, says Keay, and they are permeated by a magnetic field: Earth's. "The plasma is swirling so fast that the magnetic field can be scrambled up like spaghetti." And therein lies a source of energy for VLF waves.
~Colin Keay, Listening to Leonids (2001)
The team should read
Pierre Lescaudron and Laura Knight-Jadczyk's new book, which drops plenty of explanations from the winning Electric Universe model. Demystifying phenomena like how fireballs not only produce VLF radio waves but also electrophonic phenomena which make simultaneous seeing and hearing of fireballs possible (despite being too far removed by the speed of sound), a possible source for the strange sounds heard all over the world these latest years. These and many other not commonly acknowledged interactions of our plasma rich universe, are explained there in perfectly sound and ordinary terms, such as lightning.
Comment: The Obenberger team and New Scientist seem to be behind times, perhaps this stems from being loyal to mainstream models? The team should read Pierre Lescaudron and Laura Knight-Jadczyk's new book, which drops plenty of explanations from the winning Electric Universe model. Demystifying phenomena like how fireballs not only produce VLF radio waves but also electrophonic phenomena which make simultaneous seeing and hearing of fireballs possible (despite being too far removed by the speed of sound), a possible source for the strange sounds heard all over the world these latest years. These and many other not commonly acknowledged interactions of our plasma rich universe, are explained there in perfectly sound and ordinary terms, such as lightning.