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GlennLeDrew
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: How would the sun sound if.... new [Re: Otto Piechowski]
      #6133249 - 10/12/13 03:09 PM

At the red giant stage, the outer envelope is an even better 'vacuum' than the photosphere is now. And of course the Earth would be flying through that thin gas at near 30 km/s. What would be the sound speed in the Sun's thin envelope? How efficiently is sound propagated?

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StarWars
Mr. Postmaster Man
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Reged: 11/26/03

Loc: At the Gym >Spudtastic<
Re: How would the sun sound if.... new [Re: GlennLeDrew]
      #6133997 - 10/12/13 10:40 PM




The Sun will consume all of the oxygen and any sound would go silent...


Forever....


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scopethis
Postmaster
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Reged: 05/30/08

Loc: Kingman, Ks
Re: How would the sun sound if.... new [Re: StarWars]
      #6134876 - 10/13/13 12:06 PM

it would sound like a derailing freight train..

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derangedhermit
Pooh-Bah


Reged: 10/07/09

Loc: USA
Re: How would the sun sound if.... new [Re: GlennLeDrew]
      #6135473 - 10/13/13 05:42 PM

Quote:

At the red giant stage, the outer envelope is an even better 'vacuum' than the photosphere is now. And of course the Earth would be flying through that thin gas at near 30 km/s. What would be the sound speed in the Sun's thin envelope? How efficiently is sound propagated?



I can't figure it out well enough to get even an approximate idea of the speed of sound. It's mostly hydrogen, almost all the rest is helium. Very high (but varying by several orders of magnitude) temperature in various outer layers, which means faster speed of sound. Very low density gas (again varying by a lot by layer), which means slower speed of sound.

Due to the low pressure, I'm guessing the maximum amplitude of a continuous (non-impulse) sound will be very low. The human ear can detect a sound of one-billionth of one ATM differential, so that may be good enough. Otherwise we may need to use owls or elephants.

As far as equipment, I suspect that since a Shure SM57 microphone can get through a year of Pink Floyd touring unscathed, it can handle anything else the universe can throw at it. If not, we can ask Hotblack Desiato of Disaster Area what they use for concerts, but we'll have to wait until he's not spending a year dead for tax reasons.


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Otto Piechowski
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Reged: 09/20/05

Loc: Lexington, KY
Re: How would the sun sound if.... new [Re: derangedhermit]
      #6135532 - 10/13/13 06:06 PM

Mr. Davidson,

What does ATM mean? (I mean,other than the bank thingy).

Otto


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GlennLeDrew
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: How would the sun sound if.... new [Re: Otto Piechowski]
      #6135549 - 10/13/13 06:18 PM

ATM = atmosphere. One ATM pressure = 1013.2 millibars = 29.92 inches of mercury = 762mm of mercury = 14.7 pounds per square inch. (If I correctly remember those numbers, that is. )

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derangedhermit
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Reged: 10/07/09

Loc: USA
Re: How would the sun sound if.... new [Re: GlennLeDrew]
      #6135826 - 10/13/13 08:56 PM

I found a few online formulae, but don't trust them to be correct, even approximately, with my limited understanding.

Needed assumptions / parameters:
- the issue chosen is sound transmission in outer layers of the sun
- the hydrogen is therefore monatomic / ionic (not diatomic molecular hydrogen)
- the adiabatic constant = 5/3 (for helium and monatomic hydrogen)
- ? helium / hydrogen ratio (affects average molecular mass)
- temp range:
-- photosphere 5,700K (75% hydrogen, 24% helium))
-- chromosphere 20,000K - 1,000,000K (% helium?)
-- corona 1,000,000K - 20,000,000K (% helium?)
- all layers are plasma, not gas (the formulae for speed of sound in a gas and a plasma are different)

High-altitude simulation studies indicate that human hearing is unaffected by use at down to 1/4 standard atmospheric pressure - both in sensitivity and localization (determining direction of sound source).

I'm not sure the speed of sound actually affects our ability to hear, except for localization and, I think, partial loss of stereo effects.

The impact of a hydrogen atmosphere on listening to your quadrophonic vinyl release of Tubular Bells while dropping acid is uncertain, but worth experimentation.


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StarWars
Mr. Postmaster Man
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Reged: 11/26/03

Loc: At the Gym >Spudtastic<
Re: How would the sun sound if.... new [Re: GlennLeDrew]
      #6135902 - 10/13/13 09:42 PM



Sound travels at 750 mph from 92 million miles...


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Mister T
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Reged: 02/01/08

Loc: Upstate NY
Re: How would the sun sound if.... new [Re: StarWars]
      #6135962 - 10/13/13 10:17 PM

so it would sound like a 14 y.o.



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derangedhermit
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Reged: 10/07/09

Loc: USA
Re: How would the sun sound if.... new [Re: StarWars]
      #6136000 - 10/13/13 10:36 PM

Quote:



Sound travels at 750 mph from 92 million miles...




According to one web toolbox, the speed of sound in 20,000K helium is about 19,000 mph, and the trip would take about 200 days. I think it isn't using quite the right formula, but anyway...


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Otto Piechowski
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Reged: 09/20/05

Loc: Lexington, KY
Re: How would the sun sound if.... [Re: Mister T]
      #6136218 - 10/14/13 02:11 AM

Anthony,

What is "14 y.o."?

Otto


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Mister T
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Reged: 02/01/08

Loc: Upstate NY
Re: How would the sun sound if.... new [Re: Otto Piechowski]
      #6136297 - 10/14/13 05:30 AM


Ottoman,

92,000,000miles/ 750 miles/hr /24hr/day / 365days/yr.



Edited by Mister T (10/14/13 05:30 AM)


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Andy Taylor
Twisted, but in a Good Way
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Reged: 09/24/08

Loc: Epsom - UK
Re: How would the sun sound if.... new [Re: Mister T]
      #6137184 - 10/14/13 02:32 PM

I'd like to think that it sounds like sizzlin' bacon...

Probably just very loud "white" noise.


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derangedhermit
Pooh-Bah


Reged: 10/07/09

Loc: USA
Re: How would the sun sound if.... new [Re: Andy Taylor]
      #6138319 - 10/15/13 04:00 AM

OK, I spent another 10 minutes on this. For those who want to pursue calculating the speed of sound in plasma, the Wikipedia explanation and equation is here.

Note that just below that link, the text says "When sound spreads out evenly in all directions in three dimensions, the intensity drops in proportion to the inverse square of the distance." This is more than halfway, geometrically, accurate for sounds coming from the "surface" of the Sun toward Earth. Given that drop in intensity, the distance involved, and the low pressure, it seems clear to me that no non-impulse sound coming from there could possibly be heard (or, probably, measured) by any creature on Earth. (Pressure is relevant since it limits the amplitude of sounds that look like sine waves - the pressure cannot exceed 2x the ambient pressure, since it cannot drop below 0, but an impulse sound ("bang") does not have this limit.)

So the answer is, unless it is a mighty explosion in our direction, much louder than any sound ever made on earth (e.g. Krakatoa) we would hear nothing.

If any part of this is wrong, I'm quite confident someone will be along directly to dispute it.

Along the way, I read about the transition of Voyager 1 moving from the heliosphere into interstellar space. You can listen to a recording. But it wasn't sound that was actually recorded, it was the vibration of electrons in the very thin plasma that changed when it entered interstellar space. Still, it was / is at least partially in the right frequency range for hearing.

Also there is a completely unrelated iOS and Android app called Plasma Sounds. Fun to play with, and free. My Google-foo is weak.


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GregLee1
professor emeritus


Reged: 07/21/13

Loc: Waimanalo, HI
Re: How would the sun sound if.... new [Re: derangedhermit]
      #6138868 - 10/15/13 11:49 AM

Quote:

(Pressure is relevant since it limits the amplitude of sounds that look like sine waves - the pressure cannot exceed 2x the ambient pressure, since it cannot drop below 0, but an impulse sound ("bang") does not have this limit.)




Maybe someone could explain to me "sounds that look like sine waves"? The context here suggests that compression is somehow balanced with rarefaction. Or perhaps periodic is meant?


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derangedhermit
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Reged: 10/07/09

Loc: USA
Re: How would the sun sound if.... new [Re: GregLee1]
      #6138929 - 10/15/13 12:25 PM

Quote:

Quote:

(Pressure is relevant since it limits the amplitude of sounds that look like sine waves - the pressure cannot exceed 2x the ambient pressure, since it cannot drop below 0, but an impulse sound ("bang") does not have this limit.)




Maybe someone could explain to me "sounds that look like sine waves"? The context here suggests that compression is somehow balanced with rarefaction. Or perhaps periodic is meant?



Perhaps. I got tired of writing "non-impulse".


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Ira
Carpal Tunnel
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Reged: 08/22/10

Loc: Mitzpe Ramon, Israel
Re: How would the sun sound if.... new [Re: derangedhermit]
      #6144212 - 10/18/13 03:27 AM

Let's recast like this: The sun is a continuous fusion reaction, like a Hydrogen bomb going off, with alot of other things thrown in. So, if you could hear it would it sound like a thermonuclear detonation of huge scale or not?

/Ira


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derangedhermit
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Reged: 10/07/09

Loc: USA
Re: How would the sun sound if.... new [Re: Ira]
      #6144285 - 10/18/13 05:52 AM

I think not, out at the photosphere. The fusion is only taking place in a small central core. At the outer layers, there's convection currents, very low frequency resonances, etc. An apparent "thermonuclear detonation of huge scale" at that location would blow all that away, literally, and it doesn't. It's more like a pot boilng out there. Remember it takes a very long time for the equivalent of a photon released at the core to work its way through all that mass to the photosphere.

When you got to an altitude, working from the outside in, where there was enough pressure to hear something, I can't imagine it is silent; but I have found nothing on what the spectral power density in the audible range might be.


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Mister T
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Reged: 02/01/08

Loc: Upstate NY
Re: How would the sun sound if.... new [Re: derangedhermit]
      #6144298 - 10/18/13 06:19 AM

the nuclear fusion at the core is effective kept in a "pressure cooker" that is the gravity of the mass of the outer layers of the sun.

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Ira
Carpal Tunnel
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Reged: 08/22/10

Loc: Mitzpe Ramon, Israel
Re: How would the sun sound if.... new [Re: Mister T]
      #6147226 - 10/19/13 06:27 PM

Bummer. This may make me give up astronomy.

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