Scientists solve 30-year-old aurora borealis mystery

[derekmcd]

<p><font color="#003300"><em>UCLA space scientists and colleagues have identified the mechanism that triggers substorms in space; wreaks havoc on satellites, power grids and communications systems; and leads to the explosive release of energy that causes the spectacular brightening of the aurora borealis, also known as the northern lights.</em></font></p><p><font color="#003300"><em><span> For 30 years, there have been two competing theories to explain the onset of these substorms, which are energy releases in the Earth's magnetosphere, said Vassilis Angelopoulos, a UCLA professor of Earth and space sciences and principal investigator of the NASA-funded mission known as THEMIS (Time History of Events and Macroscale Interactions during Substorms).&nbsp; </span></em></font></p><p><font color="#003300"><em><span> One theory is that the trigger happens relatively close to Earth, about one-sixth of the distance to the moon. According to this theory, large currents building up in the space environment, which is composed of charged ions and electrons, or "plasma," are suddenly released by an explosive instability. The plasma implodes toward Earth as the space currents are disrupted, which is the start of the substorm. <br /> <br />A second theory says the trigger is farther out, about one-third of the distance to the moon, and involves a different process: When two magnetic field lines come close together due to the storage of energy from the sun, a critical limit is reached and the magnetic field lines reconnect, causing magnetic energy to be transformed into kinetic energy and heat. Energy is released, and the plasma is accelerated, producing accelerated electrons.</span></em></font></p><p><font color="#003300"><em><span>Which theory is right?&nbsp; </span><br /></em></font></p><p><font color="#003300"><em><span>"Our data show clearly and for the first time that magnetic reconnection is the trigger," said Angelopoulos, who reports the research in the July 24 online issue of the journal Science. "Reconnection results in a slingshot acceleration of waves and plasma along magnetic field lines, lighting up the aurora underneath even before the near-Earth space has had a chance to respond. We are providing the evidence that this is happening."</span> </em></font></p><p>&nbsp;</p><p>Rest of article at link:&nbsp;</p><p>http://www.physorg.com/news136127510.html</p><p>&nbsp;</p><p>This is interesting.&nbsp; I doubt this will put the debate to rest.&nbsp; If I find a paper on it, I'll post it.&nbsp; Haven't really looked for one yet. </p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[derekmcd]

<p>Here's the abstract.</p><p>http://www.sciencemag.org/cgi/content/abstract/1160495</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[MeteorWayne]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>UCLA space scientists and colleagues have identified the mechanism that triggers substorms in space; wreaks havoc on satellites, power grids and communications systems; and leads to the explosive release of energy that causes the spectacular brightening of the aurora borealis, also known as the northern lights. For 30 years, there have been two competing theories to explain the onset of these substorms, which are energy releases in the Earth's magnetosphere, said Vassilis Angelopoulos, a UCLA professor of Earth and space sciences and principal investigator of the NASA-funded mission known as THEMIS (Time History of Events and Macroscale Interactions during Substorms).&nbsp; One theory is that the trigger happens relatively close to Earth, about one-sixth of the distance to the moon. According to this theory, large currents building up in the space environment, which is composed of charged ions and electrons, or "plasma," are suddenly released by an explosive instability. The plasma implodes toward Earth as the space currents are disrupted, which is the start of the substorm. A second theory says the trigger is farther out, about one-third of the distance to the moon, and involves a different process: When two magnetic field lines come close together due to the storage of energy from the sun, a critical limit is reached and the magnetic field lines reconnect, causing magnetic energy to be transformed into kinetic energy and heat. Energy is released, and the plasma is accelerated, producing accelerated electrons.Which theory is right?&nbsp; "Our data show clearly and for the first time that magnetic reconnection is the trigger," said Angelopoulos, who reports the research in the July 24 online issue of the journal Science. "Reconnection results in a slingshot acceleration of waves and plasma along magnetic field lines, lighting up the aurora underneath even before the near-Earth space has had a chance to respond. We are providing the evidence that this is happening." &nbsp;Rest of article at link:&nbsp;http://www.physorg.com/news136127510.htmlThis is interesting.&nbsp; I doubt this will put the debate to rest.&nbsp; If I find a paper on it, I'll post it.&nbsp; Haven't really looked for one yet. &nbsp; <br />Posted by derekmcd</DIV><br /><br />MAgnetic Reconnection? SUrely you jest! <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-wink.gif" border="0" alt="Wink" title="Wink" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[MeteorWayne]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Here's the abstract.http://www.sciencemag.org/cgi/content/abstract/1160495 <br />Posted by derekmcd</DIV><br /><br />Ya know, I can't really afford SCIENCE and NATURE, but every time one of these stories comes out, I'm sure glad it will be in my mailbox in a few days!! <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Ya know, I can't really afford SCIENCE and NATURE, but every time one of these stories comes out, I'm sure glad it will be in my mailbox in a few days!! <br /> Posted by MeteorWayne</DIV></p><p>I want to get my hands on the actual pre-print paper that was submitted, but can't seem to find one.&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[derekmcd]

<p>Here's the NASA media page concerning this.&nbsp; Includes a teleconference which I don't have time to listen to ATM.&nbsp;</p><p>http://www.nasa.gov/mission_pages/themis/auroras/themis_power_media.html<br /></p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[michaelmozina]

<p><font color="#003300"><em><span><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>One theory is that the trigger happens relatively close to Earth, about one-sixth of the distance to the moon. According to this theory, large currents building up in the space environment, which is composed of charged ions and electrons, or "plasma," are suddenly released by an explosive instability. The plasma implodes toward Earth as the space currents are disrupted, which is the start of the substorm. <br /> <br />A second theory says the trigger is farther out, about one-third of the distance to the moon, and involves a different process: When two magnetic field lines come close together due to the storage of energy from the sun, a critical limit is reached and the magnetic field lines reconnect, causing magnetic energy to be transformed into kinetic energy and heat. Energy is released, and the plasma is accelerated, producing accelerated electrons.</DIV></span></em></font></p><p>I love how these articles begin with a false dichotomy by proclaiming that there are only two viable options on the table.&nbsp;&nbsp; I noticed that Alfven's/Birkeland's ideas were never even mentioned.&nbsp; How predictable.</p><p>Don't worry Wayne, I'll refrain from fully critiquing their paper in this thread for fear of being accused of "hijacking" the thread for ever daring to criticize the "experts".&nbsp; Any other criticisms I might have of their methods I'll save for my Forbidden topic thread.&nbsp; The fact they begin their main arguement with a false dichotomy fallacy doesn't look very promising.&nbsp; I certainly wouldn't rush out to by the magazine based on that article and that ridiculous arguement.&nbsp; </p> <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

 

[UFmbutler]

<p>I have the paper printed out in front of me and it is fairly interesting but it only addresses one type of substorm.&nbsp; The basics are they selected a sample of substorms and looked at parameters describing the magnetotail.&nbsp; They found that a substorm onset follows the onset of reconnection by times on the order of 90 seconds.&nbsp; The substorms that cause the aurora are dispersed, that is, their signature appears at different times based on the energy since the particles are travelling at different speeds.&nbsp; There is another common(~1/night) type of substorm without this dispersion, and the mechanism for this type is still unknown.&nbsp; That is what I am working on here at the lab...hopefully soon i'll get my own space.com article&nbsp; <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-surprised.gif" border="0" alt="Surprised" title="Surprised" /></p> <div class="Discussion_UserSignature"> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I love how these articles begin with a false dichotomy by proclaiming that there are only two viable options on the table.&nbsp;&nbsp; I noticed that Alfven's/Birkeland's ideas were never even mentioned.&nbsp; How predictable.Don't worry Wayne, I'll refrain from fully critiquing their paper in this thread for fear of being accused of "hijacking" the thread for ever daring to criticize the "experts".&nbsp; Any other criticisms I might have of their methods I'll save for my Forbidden topic thread.&nbsp; The fact they begin their main arguement with a false dichotomy fallacy doesn't look very promising.&nbsp; I certainly wouldn't rush out to by the magazine based on that article and that ridiculous arguement.&nbsp; <br /> Posted by michaelmozina</DIV></p><p>I have to agree with ya, Michael.&nbsp; The article is a bit misleading distinguishing between their two proposed theories.&nbsp; How the article sets up the two theories can lead someone to the conclusion that they difinitively detected magnetic reconnection.&nbsp; The reality, is this is not the case, nor do I believe that is their intent.&nbsp;</p><p> I finally got around to listening to the teleconference only to find out that this really isn't necessarity about the significance of magnetic reconnection.&nbsp; </p><p>I wouldn't get so defensive and call the argument ridiculous.&nbsp; What they are presenting in their argument is more about the timing of the events and not so much how or why they happen.&nbsp; They aren't arguing whether magnetic reconnection exists or not.&nbsp; They are definitely working under an a priori assumption that magnetic reconnection events are the underlying cause and/or effect, but that isn't the real significance of what they are working on.</p><p>They are still conducting some very significant science here that may have some great future benefits.&nbsp; It's more about being able to time the events and predict future episodes that inevitably happen on a much grander scale and being able to protect people and equipment from the hazards of these storm.</p><p>Still impressive the way they are able to coordinate the THEMIS network to detect this stuff.&nbsp; Hopefully, this does lead to better predictions.&nbsp; Who knows... maybe this will someday lead us to being able to harness the energy from these storms.&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[UFmbutler]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Hopefully, this does lead to better predictions.&nbsp; Who knows... maybe this will someday lead us to being able to harness the energy from these storms.&nbsp; <br /> Posted by derekmcd</DIV></p><p>The characteristic energy of the particles involved in these events is on the order of hundreds of eV to a few hundred keV, with the signature typically being stronger in the lower energy channels.&nbsp; Although they are strong enough to damage equipment, it would require an incredibly efficient capture mechanism to make harnessing this energy feasible.&nbsp; For example at these energies you'd have to capture something on the order of 10^14-10^16 electrons to just produce 1 J.&nbsp; I work with different satellites(the lab's GEO group of satellites) but the data I look at typically peaks around 10^5 electrons per unit area during a substorm. &nbsp; I suppose this signal could be amplified, but i'm not sure if substorms are the best place to look for harnessing energetic solar particles. </p> <div class="Discussion_UserSignature"> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I have the paper printed out in front of me and it is fairly interesting but it only addresses one type of substorm.&nbsp; ..Posted by UFmbutler</DIV></p><p>Do you have a link to the actual paper ?&nbsp; The stuff on the NASA web site is a bit confusing, more so since the order of events in the measured data does not appear to coincide with either model.&nbsp; <br />&nbsp;</p> <div class="Discussion_UserSignature"> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Do you have a link to the actual paper ?&nbsp; The stuff on the NASA web site is a bit confusing, more so since the order of events in the measured data does not appear to coincide with either model.&nbsp; &nbsp; <br /> Posted by DrRocket</DIV></p><p>They mention this in the teleconference.&nbsp; The overall all order doesn't fit either model.&nbsp; It seems they are most pleased with discovering where the initial event occurs being 1/3rd the distance to the moon.&nbsp; They were suprised that the following two events didn't match the predictions based on the model that has the event starting at 1/3rd the distance to the moon.</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[UFmbutler]

<p>http://www.sciencemag.org/cgi/rapidpdf/1160495v1.pdf</p><p>&nbsp;</p><p>I'm not sure if you have permission to access this without paying...if you can't, i'd be happy to email you a copy if you give me your address. </p> <div class="Discussion_UserSignature"> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>http://www.sciencemag.org/cgi/rapidpdf/1160495v1.pdfI'm not sure if you have permission to access this without paying...if you can't, i'd be happy to email you a copy if you give me your address. <br /> Posted by UFmbutler</DIV></p><p>It would be much appreciated <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-laughing.gif" border="0" alt="Laughing" title="Laughing" /></p><p>I tried to find an arxiv pre-print to no avail.&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>http://www.sciencemag.org/cgi/rapidpdf/1160495v1.pdfI'm not sure if you have permission to access this without paying...if you can't, i'd be happy to email you a copy if you give me your address. <br />Posted by UFmbutler</DIV></p><p>I'm afraid I'll have to pass and find another source.&nbsp; I don't pay AAAS dues, so I can't get to the paper.&nbsp; Maybe something will come up in Science News or the American Scientist, that I can get to.</p><p>I'm a little goosy about giving out my e-mail address in these forums.&nbsp; I am sure that you are OK, but I don't want some of the wackos getting hold of it, so I just keep it quite private.&nbsp; No offense intended, particularly since I have convinced myself that you are personally quite legitimate.</p><p>BTW welcome.&nbsp; Clear heads with real insight and a valid perspective are an asset.&nbsp; <br /></p> <div class="Discussion_UserSignature"> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I'm afraid I'll have to pass and find another source.&nbsp; I don't pay AAAS dues, so I can't get to the paper.&nbsp; Maybe something will come up in Science News or the American Scientist, that I can get to.I'm a little goosy about giving out my e-mail address in these forums.&nbsp; I am sure that you are OK, but I don't want some of the wackos getting hold of it, so I just keep it quite private.&nbsp; No offense intended, particularly since I have convinced myself that you are personally quite legitimate.BTW welcome.&nbsp; Clear heads with real insight and a valid perspective are an asset.&nbsp; <br /> Posted by DrRocket</DIV></p><p>I have a couple different emails.&nbsp; This is my junk email address.&nbsp; Spam it all you want. <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-laughing.gif" border="0" alt="Laughing" title="Laughing" /></p><p>Besides, I'll edit it out if I get the paper.</p><p>You could also try to use "add a friend" and "leave me a message" options in your account profile.&nbsp; The only folks that have access to you personal messages between "friends" are other friends on your list.&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>http://www.sciencemag.org/cgi/rapidpdf/1160495v1.pdfI'm not sure if you have permission to access this without paying...if you can't, i'd be happy to email you a copy if you give me your address. <br /> Posted by UFmbutler</DIV></p><p>Paper recieved.&nbsp; Thank you, kindly.&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>