Starship Asterisk*

Posted: **Fri Mar 25, 2011 4:05 am**

Auroral Substorm over Yellowknife

Explanation: Intense auroral activity flooded the night with shimmering colors on February 24, captured here from a lodge near the city of Yellowknife in northern Canada. The stunning sequence (left to right) of three all-sky exposures, taken at 30 second intervals, shows rapid changes in dancing curtains of northern lights against a starry background. What makes the northern lights dance? Measurements by NASA's fleet of THEMIS spacecraft indicate that these explosions of auroral activity are driven by sudden releases of energy in the Earth's magnetosphere called magnetic reconnection events. The reconnection events release energy when magnetic field lines snap like rubber bands, driving charged particles into the upper atmosphere. Stretching into space, these reconnection events occur in the magnetosphere on the Earth's night side at a distance about 1/3 of the way to the Moon.

<< Previous APOD

Discuss Any APOD

Next APOD >>

[/b]

Posted: **Fri Mar 25, 2011 4:48 am**

Uff, this should be an impressive sight to see it live.
Greetings
César

Posted: **Fri Mar 25, 2011 5:23 am**

I haven't seen the 'Northern Lights' since i was a kid over a half century ago when they were stronger and we could see them from Connecticut. As i recall they were about N/W-NN/W. Of course it was mostly like seeing them from a side view just above the trees.

Posted: **Fri Mar 25, 2011 11:28 am**

FREEEKING AWESOME!!!!!

I'm like you, Beyond: I haven't seen the northern lights since I was younger too. I lived in upstate NY then, and just remember thinking how very cool it was to see the sky looking 'ghostly' - although I don't recall seeing anything as vivid as these images! (Every time I go for a visit, I keep an 'eye to the sky', watching for them.)

Beautiful images, though. They bring back some great memories!

Posted: **Fri Mar 25, 2011 11:33 am**

Spectacular!! I've only see them once also - when I was in my 20's on a trip to upper state NY - but nothing like this series of pictures...

I hope the photographer stops by to tell us more about how he took the pictures.

Posted: **Fri Mar 25, 2011 11:50 am**

The Winters of '64-'65 I was stationed in Fairbanks, Alaska. Night after night the displays were awesome. Watching the multicolored ribbons of aurora twist and wind resembling rubber bands was worth risking frostbite from the -40C temperatures. In the 70's near Boston, MA we observed aurora often in the Winter. The aurora centers around the magnetic pole and not the geographic pole. The magnetic pole in the past 50 years apparently has wandered about 200 miles away from us. Visible auroral displays here are much less frequent now. The statement that the magnetic connections occur 1/3 of the way to the moon is a bit misleading. The magnetic field is shaped by the Sun not the moon. So the distance from the Earth is reasonable. The moon doesn't have a magnetic field and it doesn't expel charged particles toward the Earth as the Sun does.

Posted: **Fri Mar 25, 2011 12:31 pm**

Amazing pictures. I spent my college summers in the late 1960's working at a remote mine not far from Yellowknife and had the pleasure of seeing "The Show" on an on-going basis, and unfortunately pictures simply cannot capture the experience. I seem to recall a strange low pitch variable humming sound associated with the ever changing light pattern. Knowing that it was the 1960's after all, is my memory clouded or does that exist?

Posted: **Fri Mar 25, 2011 2:26 pm**

Vineyard20 wrote:
Amazing pictures. I spent my college summers in the late 1960's working at a remote mine not far from Yellowknife and had the pleasure of seeing "The Show" on an on-going basis, and unfortunately pictures simply cannot capture the experience. I seem to recall a strange low pitch variable humming sound associated with the ever changing light pattern. Knowing that it was the 1960's after all, is my memory clouded or does that exist?

http://www.pfrr.alaska.edu/aurora/faq.htm#sound wrote:
Does the aurora make sounds?
<<This question is always good for a lively discussion among residents of the north. So far, attempts to record sound during aurora have failed to produce any proof that such sounds exist, but it is hard to ignore the numerous reports that go back centuries.

There are generally two types of sounds reported to accompany the aurora. The first is a swishing sound that changes with movements in that auroral display. The second type is a crackling sound, like static electricity makes.

The problem with claims of sound that changes in time with auroral movements is that the aurora is a long ways away (100 km/60 miles), so if sound was coming from the aurora, there would be a long delay between the auroral movement and the sound arriving at the listener's ears, just as thunder arrives long after a distant lightning flash is observed. There is also the small detail that the air between us and the aurora is far too thin to carry sound over such long distances. Therefore, if this kind of sound exists, it must be created very near to the observer.

The most likely explanation for this type of sound is that it is created inside the observer's head: not a figment of the imagination, but rather leakage of the electrical impulses from the nerves in the eye (carrying images of the aurora to the brain) into the part of the brain the processes sound. In a very quiet environment, there are no sound signals for the brain to process, so it notices these tiny leakage signals and the result is sounds that change in time with the aurora. This explanation was actually tested by some early explorers, who found that the sound went away if their eyes were covered.

The second type of sound is more mysterious. A crackling sound, like static electricity sparking, might be explained by the strong electric and magnetic fields associated with the aurora, but so far theories and measurements have not provided a satisfactory explanation. Research continues.>>

Posted: **Fri Mar 25, 2011 3:01 pm**

Vineyard20 wrote:Amazing pictures. I spent my college summers in the late 1960's working at a remote mine not far from Yellowknife and had the pleasure of seeing "The Show" on an on-going basis, and unfortunately pictures simply cannot capture the experience. I seem to recall a strange low pitch variable humming sound associated with the ever changing light pattern. Knowing that it was the 1960's after all, is my memory clouded or does that exist?

This is called electrophonic sound and is reported with auroras, fireballs, storms, and other electromagnetic atmospheric phenomena. It is not well understood, and is rare enough that trying to get instrumental data is problematic. The different phenomena produce EM energy by different mechanisms, and it is uncertain whether it is heard by some sort of direct transduction in the sensory system, or by transduction to sound by conducting objects near the observer. The latter seems most likely; usually, those reporting electrophonic noise are wearing glasses or jewelry, or are near large metallic objects like garage doors or barbecue grills.

Posted: **Fri Mar 25, 2011 10:27 pm**

I have seen a few auroras; but not as brilliant as the ones pictured. I have never heard and sound but may have been too far away.

Posted: **Fri Mar 25, 2011 11:00 pm**

Hannes Alfvén is probably turning over in his honored grave! There are magnetic fields, but magnetic 'lines' do not exist - they are a figment of some astronomers' imaginations. Magnetic 'reconnection' is also a noted fallacy. The mechanism for aurora is simply the acceleration of charged particles by the Earth's magnetic field and the collision of those particles with other particles in the atmosphere. The Earth's magnetic field penetrates the atmosphere in the polar regions and that is why we have Northern and Southern 'lights', but not equatorial lights. When the solar wind is more dense, as recently from some intense solar activity, the aurora become more spectacular. ... look it up in Wikipedia, but try to ignore the nonsense about 'magnetic reconnection.'

Posted: **Sat Mar 26, 2011 12:06 am**

lankytom wrote:There are magnetic fields, but magnetic 'lines' do not exist - they are a figment of some astronomers' imaginations.

They are not merely a fiction of astronomers, but of all physicists. And for good reason: they are a very useful visualization tool, representing the vector field accurately, and in some cases (such as auroras) even having true physical meaning. Charged particles traveling along the same magnetic field line interact differently with each other than they do with particles in other lines.

Arguing against this usage is like arguing that we shouldn't use the concept of rays when analyzing optics, because there is no such physical thing as a light ray.

Magnetic 'reconnection' is also a noted fallacy.

Magnetic reconnection is a very real physical phenomenon.

The mechanism for aurora is simply the acceleration of charged particles by the Earth's magnetic field and the collision of those particles with other particles in the atmosphere. The Earth's magnetic field penetrates the atmosphere in the polar regions and that is why we have Northern and Southern 'lights', but not equatorial lights. When the solar wind is more dense, as recently from some intense solar activity, the aurora become more spectacular.

Yes, that is the simplest explanation for auroras, although it is not a complete explanation. And nothing in the APOD description suggests otherwise.

Posted: **Sat Mar 26, 2011 2:33 pm**

I have a query about the date the images were taken. The explanation states it was February 24 but the images seem to be the same as those in Kwon O Chul's gallery in TWAN where they are dated January 2011.

They are terrific images. I've never seen a live aurora so such images make me wish they could be seen where I am in England.

Posted: **Mon Mar 28, 2011 2:46 am**

lankytom wrote:Magnetic 'reconnection' is also a noted fallacy.

Chris Peterson wrote:Magnetic reconnection is a very real physical phenomenon.

Not just "real", but "very real"? Did someone step on your fundamental beliefs?

Magnetic 'reconnection' may - or may not - be a real phenomenon, or a way of describing the effects of other phenomena, an oversimplification, or even a figment of imagination. But it's likely no one KNOWS with the level of certainty with which you worded your statement.

Debate is healthy, but true debate requires respect for others' viewpoints. I for one find it disturbing when things are stated in absolutes. You're kidding yourself if you believe you know enough about the universe to be able to make any such statement in absolute terms. I've been on the receiving end of this kind of response more than once, and I can state with authority that you're alienating others and inviting conflict by writing in this style. Perhaps you could consider just putting the words "I believe" or "IMHO" (not forgetting the all important H) or even "In theory" in front of your opinions.

I'd love to hear a description of what "magnetic reconnection" actually means or shows or models or whatever in layman's terms.

-Noel

Posted: **Mon Mar 28, 2011 5:20 am**

NoelC wrote:Magnetic 'reconnection' may - or may not - be a real phenomenon, or a way of describing the effects of other phenomena, an oversimplification, or even a figment of imagination. But it's likely no one KNOWS with the level of certainty with which you worded your statement.

It is absolutely certain that it exists. To be clear, what I mean when I say that is that there is no doubt at all. Zero.

The term is a used to describe an observation. Not a theory. The observation is, however, fully supported by rich theory. You may want to start with the Wikipedia article and follow the references. Since the subject is so important in astronomy, affecting everything from auroral activity at the planetary level, through stellar activity, to galactic scale fields and maybe larger, there are a wealth of scientific papers available on the subject. AFAIK, none argue it isn't a real, physical thing.

Debate is healthy, but true debate requires respect for others' viewpoints.

Debate is healthy in some cases, but not all. Debating the existence of something that is part of mainstream scientific understanding is seldom useful or healthy, and in many cases violates the terms of this forum.

Posted: **Mon Mar 28, 2011 8:25 am**

Chris Peterson wrote:Debate is healthy in some cases, but not all. Debating the existence of something that is part of mainstream scientific understanding is seldom useful or healthy, and in many cases violates the terms of this forum.

Electric Universe/Plasma Cosmology is not a topic that is open for discussion on this board.

Posted: **Mon Mar 28, 2011 2:36 pm**

bystander wrote:
Chris Peterson wrote:Debate is healthy in some cases, but not all. Debating the existence of something that is part of mainstream scientific understanding is seldom useful or healthy, and in many cases violates the terms of this forum.
Electric Universe/Plasma Cosmology is not a topic that is open for discussion on this board.

Yes, but the discussion of magnetic reconnection, which is a well understood physical phenomenon, does not fall into that particular category.

Posted: **Mon Mar 28, 2011 3:42 pm**

Chris Peterson wrote:Yes, but the discussion of magnetic reconnection, which is a well understood physical phenomenon, does not fall into that particular category.

No, but the OP that started the discussion did. I was reinforcing your comment.

Posted: **Mon Mar 28, 2011 4:53 pm**

Chris Peterson wrote:The term is a used to describe an observation. Not a theory.

I accept that, but it's quite clear the person who originally made the comment does not consider it thus. And your response initially did nothing to explain your viewpoint.

The argument becomes, then, something like a debate whether "gravity" is a force in itself or a side effect of space-time distortion by mass. You can say "gravity" absolutely exists, but those who say it's no more than an observation of the effect of a deeper reality might disagree - with a great deal of context being left unsaid.

It seems kind of a meaningless debate if it's just about semantics, and especially considering that there are those who get benefit out of naming "magnetic reconnection" and using it to further their field of study. It can become somewhat more meaningful, however, if it's a scientific debate about whether it's the best way to think about things to further scientific progress.

Once people said the world was "flat" because the part they could observe certainly looked that way. Those who challenged that view because they understood reality at a higher level were originally put down by people who just "knew" how it was.

Keep an open mind.

-Noel

Posted: **Thu Apr 07, 2011 1:16 pm**

Real-time Observatory Captures Stunning Recent Auroras (over Yellowknife)
Universe Today | Nancy Atkinson | 2011 Apr 07

The online observatory AuroraMAX, which offers live-streaming views of Canada’s northern lights, has seen an uptick in recent aurora activity, and the latest images the team has released are nothing short of stunning. The image above was taken early this morning, April 7, 2011. AuroraMAX is monitoring the intensity and frequency of the Aurora Borealis above their cameras in Canada in the years leading up to Solar Maximum, expected in 2013. In addition to nightly broadcasts of the aurora, AuroraMAX is helping demystify the science behind the phenomenon, as well as providing tips for seeing and photographing auroras.
...
Click each image caption to access AuroraMAX’s Twitpic page, where they frequently post images from their nightly observations.

And check out the AuroraMAX website for more information on how you can watch nightly webcasts of aurora activity.