New theory may explain the ‘music of the meteors’

Interesting. This explains why it is possible to "hear" hissing and other sounds from meteors even though the "sound" should come much later. Informative article, highlights of the explanation below:


www.sciencemag.org...

Meteors release huge amounts of energy as they disintegrate in the atmosphere. They also produce low frequency radio waves that travel at the speed of light. Some scientists have suggested that those radio waves produce the sound that accompanies meteors.

The waves can cause everyday objects—including fences, hair, and glasses—to vibrate, which our ears pick up as sound between 20 and 20,000 Hertz. This phenomenon, called electrophonics, is a well-known principle: “The conversion from electromagnetic waves to sound waves … is exactly how your radio works,” says Colin Price, an atmospheric scientist at Tel Aviv University in Israel and co-author of the new study. “But in this case nature provides the conversion between electromagnetic waves and acoustic waves.”

People have said they hiss sometimes but I never heard them. I have heard the northern lights hiss a couple of times in the past, you have to be out by a quiet lake to hear them hiss. At least that is the only time I ever heard them hiss, when I was by a calm lake way out in the country.

I will never forget the time I heard a meteor. It was not instant, it had a few seconds of delay.

It was a very quiet night out in the middle of the high desert. Normally at this location you could hear people a mile away talking with a normal volume voice - that is how quiet it is there.

Suddenly I saw the bright white meteor streak across the sky with about a 1 second lifetime right above me. A few seconds after the meteor disappeared I heard an extremely loud electrical sound come from the sky "zzzzzzzzzzzzap!".

The duration of the sound was exactly the same duration that the meteor was visible. Also, there was no doubt the sound came from the sky, the same direction of the meteor. Because the duration of the sound matched the lifetime of the meteor, and the direction matched, there was no doubt at all in my mind the sound was related to the meteor.

To me it was not a hiss, it was a zap like an electrical ark. Exactly like this:


From that point on I contemplated the electrical nature of meteors. Perhaps the meteor is a conductor, and Eddy Currents are induced in the meteor because the Earth is a magnet, and the meteor is moving fast. This would then heat the meteor inside out, and make it glow bright white, and then super heat the air in such a way to make a zapping sound just like electric arc would.

I've seen a shooting star playing "Innagaddadavida."
I got better.

originally posted by: infolurker
This phenomenon, called electrophonics, is a well-known principle: “The conversion from electromagnetic waves to sound waves … is exactly how your radio works,” says Colin Price, an atmospheric scientist at Tel Aviv University in Israel and co-author of the new study. “But in this case nature provides the conversion between electromagnetic waves and acoustic waves.”

This is why atmospheric scientists don't do radio designs. No. It's NOT 'exactly how radios work'. It's not even close.

When I get time, I'm going to get the text of his paper and see what he did - it's most DEFINITELY not straightforward to produce a large amount of VLF propagating radio waves in a lab. As in, "nuh-uh, you din't" You can get some nice high frequency magnetic fields but that's not VLF radio waves. Now, a non-coupled magnetic field produces magnetostriction in materials, and THAT will make a sound.

originally posted by: rickymouse
People have said they hiss sometimes but I never heard them. I have heard the northern lights hiss a couple of times in the past, you have to be out by a quiet lake to hear them hiss. At least that is the only time I ever heard them hiss, when I was by a calm lake way out in the country.

I've heard them too. I've seen a lot of meteors and never heard one, though.

originally posted by: More1ThanAny1
From that point on I contemplated the electrical nature of meteors. Perhaps the meteor is a conductor, and Eddy Currents are induced in the meteor because the Earth is a magnet, and the meteor is moving fast. This would then heat the meteor inside out, and make it glow bright white, and then super heat the air in such a way to make a zapping sound just like electric arc would.

The Earth's field is really weak. You wouldn't get much in the way of eddy currents. However, they could easily make a 'bang' by passing over you at supersonic velocities, by just leaving a tiny sonic boom.

originally posted by: rickymouse
People have said they hiss sometimes but I never heard them. I have heard the northern lights hiss a couple of times in the past, you have to be out by a quiet lake to hear them hiss. At least that is the only time I ever heard them hiss, when I was by a calm lake way out in the country.

Perhaps you are on to something behind the reason for the sound. Why consider a meteor a mere hunk of rock or metallic material? The meteors come from outside our physical sphere and bring totally unknown may carry energy (electrical) charges with it. The larger one, our earth, cancels/discharges the smaller one and it protests to the best of its abilities.

Who hasn't heard the sizzle of an electrical discharge? That the sound of a meteor is evident (soon) locally and not delayed by the speed of sound is indicative that the effect causing the sensation is electrical, somewhat like the way light expands from its source. A silly proposition, but it works for me (of limited means).

originally posted by: More1ThanAny1
I will never forget the time I heard a meteor. It was not instant, it had a few seconds of delay.

It was a very quiet night out in the middle of the high desert. Normally at this location you could hear people a mile away talking with a normal volume voice - that is how quiet it is there.

Suddenly I saw the bright white meteor streak across the sky with about a 1 second lifetime right above me. A few seconds after the meteor disappeared I heard an extremely loud electrical sound come from the sky "zzzzzzzzzzzzap!".

The duration of the sound was exactly the same duration that the meteor was visible. Also, there was no doubt the sound came from the sky, the same direction of the meteor. Because the duration of the sound matched the lifetime of the meteor, and the direction matched, there was no doubt at all in my mind the sound was related to the meteor.

To me it was not a hiss, it was a zap like an electrical ark. Exactly like this:

From that point on I contemplated the electrical nature of meteors. Perhaps the meteor is a conductor, and Eddy Currents are induced in the meteor because the Earth is a magnet, and the meteor is moving fast. This would then heat the meteor inside out, and make it glow bright white, and then super heat the air in such a way to make a zapping sound just like electric arc would.

When you have a meteor burning up in the atmosphere and glowing, you have molecules being ionized, and those free electrons will give off photons at all wavelengths; visible light, infra-red, radio frequencies. Maybe an iron-nickel meteorite can become a basic radio transmitter given the gradient fields of electrical charge.

But for something to convert radio waves into sound, it needs a tuned antennae, a form of amplification (valves, transistors), an energy source and a sound source like a loud speaker. The natural currents running through the Earth's surface combined with metal objects could act as a loudspeaker.

We used to have experiement in high-school physics using spark generators. A spark generated by one copper ring would induce a spark to be generated by another copper ring on the other side of the classroom. Scale that up by the size and speed of a meteorite, and it would be possible to transmit sound.

This was already explained by bad company in 1975



With thanks to my hero jimmy page for "discovering" them..

-Chris

I wonder if you can really hear a meteor, or it's a phenomenon similar to thinking you can hear sounds from a soundless GIF, such as "hearing" the elephants hit the seesaw in this GIF:

To add to my post above...

To me, trying to find a physical explanation for some people saying that they hear a sound accompanied with a meteor is similar to people who tried to find a physical explanation for why the Moon appears larger on the horizon that it does when it is over our heads.

Some people came up with theories that the Moon is larger because the thicker atmosphere at the horizon is magnifying it. However, the truth of it is that the Moon is NOT larger at the horizon, and all someone needed to do to realize that was measure it at the horizon and measure it again later that night when it is overhead.

They would have seen that the measurements were the same, and the apparent size difference was only an optical illusion, probably caused by the way we perceive the size by comparing the Moon to objects on the horizon in the same line of sight. In the case of the meteor hiss, that may only be an "aural" illusion (like the elephant GIF), and not a real sound.

originally posted by: Bedlam
When I get time, I'm going to get the text of his paper and see what he did - it's most DEFINITELY not straightforward to produce a large amount of VLF propagating radio waves in a lab. As in, "nuh-uh, you din't" You can get some nice high frequency magnetic fields but that's not VLF radio waves. Now, a non-coupled magnetic field produces magnetostriction in materials, and THAT will make a sound.

The theory uses the ionosphere.

Now, Price and Michael Kelley, a physicist at Cornell University, have developed a model to answer that question. As a meteor streaks through Earth’s atmosphere, it ionizes the air around it, splitting it into heavy, positively charged ions and lighter, negatively charged electrons. The ions follow the meteor, whereas the electrons are deflected by Earth’s magnetic field. That separation of positive and negative charges in the meteor’s wake produces a large electric field that drives an electrical current. And it’s that current that launches the radio waves, Price and Kelley hypothesize in an upcoming issue of Geophysical Research Letters. The size of the meteor and its speed through the atmosphere would control the frequency of the radio waves, they predict.

onlinelibrary.wiley.com...

Recorded for centuries, people can hear and see meteors nearly concurrently. Electromagnetic energy clearly propagates at the speed of light and converts to sound (called electrophonics) when coupled to metals. An explanation for the electromagnetic energy source is suggested. Coma ions around the meteor head can easily travel across magnetic field lines up to ~120 km. The electrons, however, are tied to magnetic field lines, since they must gyrate around the field above ~75 km. A large ambipolar electric field must be generated to conserve charge neutrality. This localized electric field maps to the E region then drives a large Hall current that launches the electromagnetic wave. Using antenna theory and following, a power flux of over 10−8 W/m2 at the ground is found. Electrophonic conversion to sound efficiency then needs to be only 0.1% to explain why humans can hear and see meteors nearly concurrently.

In sum they propose a mechanism for large-scale charge separation in the atmosphere and then its relaxation which creates the EM wave with a huge wavelength as its geophysical in extent. It's only half crazy, unlike the ideas on this thread.

In total lay-mans terms it would makes sense a meteor would make some kind of noise due to the speed and friction as it moves thru the atmosphere. Whether it's loud enough for us to hear would depend on many factors, I would think.

The friction would probably be similar to rubbing a ballon on the carpet. Only with sparking.

I can't see either how anyone would get radio waves out of the phenomena but the again I'm thinking radio waves like a short wave radio or my local radio station. Not the more technical type frequencies that "count" but are different.

Yup....Meteors for Dummies.
You're welcome!

originally posted by: Caver78
In total lay-mans terms it would makes sense a meteor would make some kind of noise due to the speed and friction as it moves thru the atmosphere. Whether it's loud enough for us to hear would depend on many factors, I would think.

The friction would probably be similar to rubbing a ballon on the carpet. Only with sparking.

I can't see either how anyone would get radio waves out of the phenomena but the again I'm thinking radio waves like a short wave radio or my local radio station. Not the more technical type frequencies that "count" but are different.

Yup....Meteors for Dummies.
You're welcome!

Well, of course meteors make a sound, they are large and enter the atmosphere at hypersonic speeds and make an acoustical shock wave, but the point is that the speed of sound propagation means that you should be able to hear a meteor minutes from the time you see it, and people have reported hearing sounds almost simultaneously. And that mystery is the current subject---the theory proposed by the planetary scientists is that the meteor's travel through the ionosphere can setup conditions to create large electromagnetic waves which become audible when they interact with the ground. So you are hearing the ''hissing'' from everywhere nearby which is reasonably conductive.

The large meteor over Russia a few years back made a loud and damaging acoustic shock-wave but it came a substantial time after the meteor was visible. All recorded and on youtube these days.

a reply to: Caver78

It should also be noted that meteors burn up 60 miles up -- so they are AT LEAST 60 miles away from you (if the are right overhead), and possibly 100+ miles from you if it is somewhere between the horizon and right over head.

Therefore, sound could take 4 or 5 minutes to travel 60 miles (and that's assuming a constant density of air between the meteor and you -- which by the way is NOT the case because the air is thinner at altitude and sound would carry more slowly).

So if people really are hearing anything, it isn't sound waves, because how in the world would they know a faint hiss they hear 4 or five minutes after a meteor was from that meteor? That's where this radio wave hypothesis comes into play -- because the radio waves would move at the speed of light, so there would be no noticeable time delay.

However, I think it is much more likely that people are not really hearing a hiss, but just think they are, due to their brain picking up the visual clue of the meteor, and the brain adding a sound that isn't really there.


Edit to add:
mbkennel types up his thoughts much faster than I do.
Sorry if some of my explanation seems to repeat idea he said above, but I just took longer to type and post.

a reply to: mbkennel

A few big issues- that's a lot of power density- I assume you meant 10E8 W per square meter at the ground. 1 billion Watts per square meter seems a bit much. Hopefully I just misread that.

Second, we've got some really big VLF antennae, not near a freaking billion watts per square meter. But nice. You don't get hissing noises from them.

Also at 10e8 W/m2, you'd think you would have received huge mongo signals from VLF receivers that would be totally unmistakable.

Yet, no. Also, and it's filtered through journalists, but they seemed to be claiming they were replicating it in the lab. There's no way to be out of the near field. Propagating EM works differently than bare E or H fields.

a reply to: Soylent Green Is People

Sorry but I disagree. My brain didn't just make a sound. That is ridiculous.

The time between the meteor and the sound was about 10 seconds. It's not a faint hiss. It was a fairly audible zzzzzzzzz sound like an electrical arc. The sound definitely originated from the sky, there is no doubt about that. The correlation between the meteor and the sound mostly comes from the sound duration being exactly the same duration as the visibility of the meteor.

I would believe it is caused by some unknown yet to be discovered natural phenomena before I consider the ridiculous notion that my brain just made a sound that obviously originated from the sky.

originally posted by: More1ThanAny1
a reply to: Soylent Green Is People

Sorry but I disagree. My brain didn't just make a sound. That is ridiculous.

The time between the meteor and the sound was about 10 seconds. It's not a faint hiss. It was a fairly audible zzzzzzzzz sound like an electrical arc. The sound definitely originated from the sky, there is no doubt about that. The correlation between the meteor and the sound mostly comes from the sound duration being exactly the same duration as the visibility of the meteor.

I would believe it is caused by some unknown yet to be discovered natural phenomena before I consider the ridiculous notion that my brain just made a sound that obviously originated from the sky.

The ten-second delay is odd because if the sound were radio waves, then they would move at the speed of light. A ten-second delay in radio waves reaching you at the speed of light would mean that the meteors were more than 7 times farther than the Moon -- and they are not.

If it were sound waves that took only 10 seconds to reach you, then the meteors would be only 2 miles away -- and they are not.

So if you are hearing something real, then it isn't from either sound waves or radio waves emanating from the meteor you see.

By the way, the brain certainly is capable of making us think we hear a sound where the is none, such as those silent GIFs with which we can swear we hear something. Sight and sound are produced not by the eye or ear, but by the brain. The brain takes data from the eyes and ears, but the brain then presents us with what it THINKS the sight or the sound should be -- but not the actual sight and sound.

Everything we perceive is created by and filtered by our brains based on not just audio inputs, but also visual clues -- plus other sensory I'm[puts and our experiences and our memories. All of these things come together and result in the things your brain tells us we hear.

Here's an interesting video about auditory illusions. While it doesn't touch upon how the brain can makes us think we hear things when there is nothing to hear, it does show how what our brains say we are hearing is heavily influenced by what we are seeing (in the case of the McGurk effect, explained in the video), and how other forces other than the actual sound itself influence what our brains say we are hearing.

originally posted by: Bedlam
a reply to: mbkennel

A few big issues- that's a lot of power density- I assume you meant 10E8 W per square meter at the ground. 1 billion Watts per square meter seems a bit much. Hopefully I just misread that.

Yeah, it's 10^-8 of course.

Yet, no. Also, and it's filtered through journalists, but they seemed to be claiming they were replicating it in the lab. There's no way to be out of the near field. Propagating EM works differently than bare E or H fields.

Which is why I try to find the original paper source, as I did here. Geophysical Research Letters is the top journal in planetary physics. The generation and propagation length scale is over planetary size distances because of the wavelengths of course.