Largest storm ever seen on Saturn by far...

[Sunny129]

http://www.huffingtonpost.com/2011/07/08/saturn-storm-cassini-photos_n_892683.html?ref=tw

the Huffington Post reported on a storm spotted by the Cassini spacecraft. follow the link for the full article and some interesting facts and very cool photos. what interests me the most is the NASA statement that they quoted in the article:

The storm is about 500 times larger than the biggest storm previously seen by Cassini during several months from 2009 to 2010. Scientists studied the sounds of the new storm's lightning strikes and analyzed images taken between December 2010 and February 2011. Data from Cassini's radio and plasma wave science instrument showed the lightning flash rate as much as 10 times more frequent than during other storms monitored since Cassini's arrival to Saturn in 2004. The data appear in a paper published this week in the journal Nature.

specifically, i'm wondering about the bolded part. how can NASA study the sounds of lightning (or more appropriately thunder), let alone any sound whatsoever, without being immersed in the planet's atmosphere? certainly Cassini isn't hearing these sounds from its orbit far above Saturn's atmosphere since sound doesn't travel through empty space...and before someone mentions that space isn't actually empty, interplanetary space empty enough that any bits of matter occupying that space (atoms, molecules, etc) are out of contact with each other more often than they touch, and therefore cannot transmit the perturbations of matter than we interpret as sound. so then how is NASA studying sounds produced in the atmosphere of another planet?

 

[yottabit]

http://www.huffingtonpost.com/2011/07/08/saturn-storm-cassini-photos_n_892683.html?ref=tw

the Huffington Post reported on a storm spotted by the Cassini spacecraft. follow the link for the full article and some interesting facts and very cool photos. what interests me the most is the NASA statement that they quoted in the article:

specifically, i'm wondering about the bolded part. how can NASA study the sounds of lightning (or more appropriately thunder), let alone any sound whatsoever, without being immersed in the planet's atmosphere? certainly Cassini isn't hearing these sounds from its orbit far above Saturn's atmosphere since sound doesn't travel through empty space...and before someone mentions that space isn't actually empty, interplanetary space empty enough that any bits of matter occupying that space (atoms, molecules, etc) are out of contact with each other more often than they touch, and therefore cannot transmit the perturbations of matter than we interpret as sound. so then how is NASA studying sounds produced in the atmosphere of another planet?

The first thing that comes to my mind is a laser vibrometer, but I have no idea if that's the equipment that they actually use

Lasers can be used to transmit or receive sonic and ultrasonic vibrations from a distance for sure though

 

[bobdole369]

They picked up the electrical charges as radio, which does travel through space.

 

[Sunny129]

They picked up the electrical charges as radio, which does travel through space.

good point. it seems the solution is far simpler than i had imagined. but i'm still interested in the specifics. here on earth for example, a radio station transmits its signal on specific wavelengths of the EM spectrum (radio waves, which are ~30cm or longer). we use receivers to change those radio waves back into sound. obviously the Cassini spacecraft has some sort of receiver that does that. but what exactly is acting as the transmitter? in other words, what exactly is encoding the sounds of thunder into radio waves in the first place?

perhaps i'm misunderstanding the article...after all, NASA made no mention of thunder, and actually stated that they were just listening to the sounds of lightning. perhaps that is exactly what makes this possible - the lightning itself is electricity, and as such, it releases EM energy when it strikes. maybe the Cassini spacecraft is just scanning a sub-range of radio frequencies in search for energy produced by the lightning in the radio wave range of the EM spectrum, and then turning it into sound to be studied. of course this wouldn't be a indirect interpretation of the sound of thunder on Saturn, but simply EM radiation turned into sound...

 

[yottabit]

the lightning itself is electricity, and as such, it releases EM energy when it strikes

This exactly. I should've thought of that before 😛 It's a little misleading in the article, they aren't really listening to thunder or the "sound" of the lightning strike.

They are most likely A) analyzing the wave form of the EM put off by the lightning strikes or B) listening to the "sound" that is generated by playing that same EM waveform back on speakers.

 

[Sunny129]

They are most likely A) analyzing the wave form of the EM put off by the lightning strikes or B) listening to the "sound" that is generated by playing that same EM waveform back on speakers.

I had a feeling that this was more or less the nature of Cassini's experimental observations, but i think NASA oversimplified it for the layman to the point that folks are misinterpreting the actual content of what they're studying.

 

[Ghiedo27]

Lightning at Saturn creates phenomena known as Saturn electrostatic discharges, which are like the static that Earth lightning creates on an AM radio. The amplitude and duration of the Saturn lightning radio signals were used to create the audio signals heard here.

It's not really true audio from what I'm reading from NASA's site. The electrostatic discharge has some amplitude irregularity, but it's a stretch to think that it's representative of what you would actually hear in the storm.

 

[JeffreyLebowski]

I wonder if there is a group of Saturnarians blaming Global Warming on this?

 

[silverpig]

You can determine what it would sound like by watching how the atmosphere moves. They do this with stars all the time. There's a video of the sun where you can watch the surface ripple and bubble. You then do a spherical harmonic basis fourier transform to get the power spectrum of the sound (read: you do fancy math on the image to get the boom boom), and then frequency shift it into our audible range. This is how they figure out what the interior of a star looks like.

You can do something similar to other stars by measuring light curves (brightening and dimming) to at least look at a few of the vibrational modes. This field of study is asteroseismology. My wife has a paper published in this field actually.

So, there are remote sensing methods for detecting vibrations in a fluid from a distance, from which you can reconstruct the sound.

I haven't RTFA so I don't know if this is what they mean, or even if Cassini has the instruments to do this type of thing, but I suppose it could be possible to do.

 

[Ghiedo27]

NASA says outright that it's just static from amplitude variance in the electrostatic discharge (link).

 

[Sunny129]

I haven't RTFA so I don't know if this is what they mean, or even if Cassini has the instruments to do this type of thing, but I suppose it could be possible to do.

i don't think that's what they're doing with Cassini. here, they're actually listening to the radio noise produced by lightning in Saturn's atmosphere, and not the atmosphere itself. not that Saturn can't be listened to in the same way a star can be listened to via astroseismology - i agree with you that it should be possible to do...although i'd imagine there'd be some dramatic differences, even though both objects are gaseous and most certainly foster regions of different densities through convection, rotation, and other processes. after all, one is quite massive and made of million to billion degree plasma whose convection and rotational friction produces massive electric and magnetic fields, whereas the other is a considerably smaller mass of far less ionized gas (much less of a plasma) whose convection and rotation produces far smaller electric or magnetic fields in and around its gaseous atmosphere.

without getting too far off topic, what exactly are scientists "hearing" when they apply an FFT to the movement of a particular surface region of a star? are they hearing radio noise like the lightning in Saturn's atmosphere produces? or are they hearing some other kind of "sound?" i have a feeling that, while both studies are yielding a false sense of actual sound, they're both using their respective "sounds" as a means of further studying and analyzing their data, as opposed to literally saying "this is actually what the sun's plasma sounds like as it convects" or "this is what lightning (not the thunder, but the lightning itself) sounds like."

 

[pw38]

I think the turbulence seen is pretty fascinating since normally from that distance Saturn looks quite dull compared to Jupiter.

 

[wirednuts]

i cant wait until we find another earth like planet. im just curious as hell as to how both life forms would coexist. could we eat the plants? is it ok if we get infections from the animals? its just fascinating to me and i cant wait to find that place.

 

[silverpig]

without getting too far off topic, what exactly are scientists "hearing" when they apply an FFT to the movement of a particular surface region of a star? are they hearing radio noise like the lightning in Saturn's atmosphere produces? or are they hearing some other kind of "sound?"

If you were able to fill space with a fluid and put yourself and the sun in said fluid, they are detecting the sound you would actually hear. Sort of. They often frequency shift everything if they are going to stick it into a .wav file for people to actually listen to.

Basically, imagine taking a big ball of fluid and hitting it with a big space hammer. The fluid would vibrate and wobble - ringing. That's what they detect, the actual physical vibrations.

Stanford solar center site

mp3 of the ringing of the sun. It's just a few of the lower modes. I'm sure all of them together would just sound like static.

 

[Ghiedo27]

I have a feeling that, while both studies are yielding a false sense of actual sound, they're both using their respective "sounds" as a means of further studying and analyzing their data, as opposed to literally saying "this is actually what the sun's plasma sounds like as it convects" or "this is what lightning (not the thunder, but the lightning itself) sounds like."

Kinda like what they do do photos to show ultraviolet and infrared.

edit:

[FONT=Arial, Helvetica, sans-serif]The Sun's sound waves are normally at frequencies too low for the human ear to hear. To be able to hear them, the scientists sped up the waves 42,000 times -- and compressed 40 days of vibrations into a few seconds.[/FONT]

[FONT=Arial, Helvetica, sans-serif][/FONT]
Once you frequency shift something that much it's misleading to say that you're hearing the sun.

 

[silverpig]

i cant wait until we find another earth like planet. im just curious as hell as to how both life forms would coexist. could we eat the plants? is it ok if we get infections from the animals? its just fascinating to me and i cant wait to find that place.

I'm more interested in if we could BBQ the animals!

 

[silverpig]

Kinda like what they do do photos to show ultraviolet and infrared.

edit:
[FONT=Arial, Helvetica, sans-serif][/FONT]
Once you frequency shift something that much it's misleading to say that you're hearing the sun.

They're only taking the lowest modes so they have to speed them up. I'm sure there are kHz frequency oscillations too, but they didn't have the bandwidth to record it all.

I dunno... it's still physical vibration. Electron microscope "images" are much less real because there is no way to get those pictures with light.

 

[Ghiedo27]

I'm with you 90% of the way, I only mentioned it because that's an extreme example of alteration and technical enough where it's easy to gloss over the fact that it is shifted. I don't think anyone is out there at night yelling at children that they aren't really looking at stars because of the red shift! :biggrin:

Well, at least I hope not. . . :ninja:

 

[Jeff7]

...
Once you frequency shift something that much it's misleading to say that you're hearing the sun.

Most of the public will understand "sounds." They're less likely to understand something like "wideband electromagnetic static bursts produced by electrical discharges, frequency-shifted into the audible spectrum."