APOD: A SAR Arc from New Zealand (2024 Jan 03)

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APOD: A SAR Arc from New Zealand (2024 Jan 03)

Post by APOD Robot » Wed Jan 03, 2024 5:05 am

Image A SAR Arc from New Zealand

Explanation: What is that unusual red halo surrounding this aurora? It is a Stable Auroral Red (SAR) arc. SAR arcs are rare and have only been acknowledged and studied since 1954. The featured wide-angle photograph, capturing nearly an entire SAR arc surrounding more common green and red aurora, was taken earlier this month from Poolburn, New Zealand, during an especially energetic geomagnetic storm. Why SAR arcs form remains a topic of research, but is likely related to Earth's protective magnetic field, a field created by molten iron flowing deep inside the Earth. This magnetic field usually redirects incoming charged particles from the Sun's wind toward the Earth's poles. However, it also traps a ring of ions closer to the equator, where they can gain energy from the magnetosphere during high solar activity. The energetic electrons in this ion ring can collide with and excite oxygen higher in Earth's ionosphere than typical auroras, causing the oxygen to glow red. Ongoing research has uncovered evidence that a red SAR arc can even transform into a purple and green STEVE.

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d.j.j.g.

Re: APOD: A SAR Arc from New Zealand (2024 Jan 03)

Post by d.j.j.g. » Wed Jan 03, 2024 1:38 pm

About 1998, I stepped outside at six o'clock in the morning in Minnesota to walk our dog. I thought that there was a gray, flashing police light on the street, but I immediately looked up and saw instead that the sky was going mad with motion. There were gray splotches swirling about the sky zooming from the northwest to the southeast. It all looked like blotches of oil on water, but they were zooming so fast, that they seemed to go hundreds of miles in just a few seconds. The drops or blotches were zooming around in circles, then zipping on to the southeast. It all completely filled that passage across the sky. I woke the rest of the family, and we all got to see this. As the dawn came up more brightly, it all faded. I had supposed that this was auroral activity, but I've never seen a picture of auroras like this. And no one has ever explained this phenomenon to me. Does anyone here know what it might have been? There were no colors other than various shades of gray.

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Re: APOD: A SAR Arc from New Zealand (2024 Jan 03)

Post by johnnydeep » Wed Jan 03, 2024 2:19 pm

d.j.j.g. wrote: Wed Jan 03, 2024 1:38 pm About 1998, I stepped outside at six o'clock in the morning in Minnesota to walk our dog. I thought that there was a gray, flashing police light on the street, but I immediately looked up and saw instead that the sky was going mad with motion. There were gray splotches swirling about the sky zooming from the northwest to the southeast. It all looked like blotches of oil on water, but they were zooming so fast, that they seemed to go hundreds of miles in just a few seconds. The drops or blotches were zooming around in circles, then zipping on to the southeast. It all completely filled that passage across the sky. I woke the rest of the family, and we all got to see this. As the dawn came up more brightly, it all faded. I had supposed that this was auroral activity, but I've never seen a picture of auroras like this. And no one has ever explained this phenomenon to me. Does anyone here know what it might have been? There were no colors other than various shades of gray.
Not sure, but perhaps your eyes were only seeing shades of gray because it often takes photographic equipment to bring out colors. For example, from https://earthsky.org/earth/will-you-see ... an-aurora/, perhaps you were seeing something more like the upper middle picture in this grid:

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d.j.j.g.

Re: APOD: A SAR Arc from New Zealand (2024 Jan 03)

Post by d.j.j.g. » Wed Jan 03, 2024 2:52 pm

That's quite possible. I never thought of that. I should add that it was rather toward springtime, and the sun was somewhat well up already. One thing that puzzled us was that there were no curtainy effects, no typical (as most know them) aurora sights. And it was all almost blindingly fast! Things moved from one end of the sky to another in just a few seconds. Perhaps, as you suggest, it was a type of aurora after all. Thank you!

Jim Armstrong

Re: APOD: A SAR Arc from New Zealand (2024 Jan 03)

Post by Jim Armstrong » Wed Jan 03, 2024 5:22 pm

I think pictures of aurorae should be on an APOD site where A stands for Atmospheric.

If they are astronomical, then they are unique in only having been observed by some quite small percent of all the humans who have ever lived.

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Re: APOD: A SAR Arc from New Zealand (2024 Jan 03)

Post by Chris Peterson » Wed Jan 03, 2024 5:49 pm

Jim Armstrong wrote: Wed Jan 03, 2024 5:22 pm I think pictures of aurorae should be on an APOD site where A stands for Atmospheric.

If they are astronomical, then they are unique in only having been observed by some quite small percent of all the humans who have ever lived.
As opposed to, say... other galaxies?
Chris

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Re: APOD: A SAR Arc from New Zealand (2024 Jan 03)

Post by johnnydeep » Wed Jan 03, 2024 6:12 pm

Chris Peterson wrote: Wed Jan 03, 2024 5:49 pm
Jim Armstrong wrote: Wed Jan 03, 2024 5:22 pm I think pictures of aurorae should be on an APOD site where A stands for Atmospheric.

If they are astronomical, then they are unique in only having been observed by some quite small percent of all the humans who have ever lived.
As opposed to, say... other galaxies?
I'm not sure what you mean by that. That other galaxies have only been observed by a small percentage of all humans who have ever lived? That's true of course, but other galaxies might still be more properly deemed "APOD"s where the "A" stands for "astronomy" instead of "atmospheric" (at least according to the OP).
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Re: APOD: A SAR Arc from New Zealand (2024 Jan 03)

Post by Chris Peterson » Wed Jan 03, 2024 6:22 pm

johnnydeep wrote: Wed Jan 03, 2024 6:12 pm
Chris Peterson wrote: Wed Jan 03, 2024 5:49 pm
Jim Armstrong wrote: Wed Jan 03, 2024 5:22 pm I think pictures of aurorae should be on an APOD site where A stands for Atmospheric.

If they are astronomical, then they are unique in only having been observed by some quite small percent of all the humans who have ever lived.
As opposed to, say... other galaxies?
I'm not sure what you mean by that. That other galaxies have only been observed by a small percentage of all humans who have ever lived? That's true of course, but other galaxies might still be more properly deemed "APOD"s where the "A" stands for "astronomy" instead of "atmospheric" (at least according to the OP).
Just pointing out that there is nothing remotely "unique" in astronomical phenomena that have only been observed by a tiny percentage of all humans who have ever lived!
Chris

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Re: APOD: A SAR Arc from New Zealand (2024 Jan 03)

Post by johnnydeep » Wed Jan 03, 2024 6:29 pm

Chris Peterson wrote: Wed Jan 03, 2024 6:22 pm
johnnydeep wrote: Wed Jan 03, 2024 6:12 pm
Chris Peterson wrote: Wed Jan 03, 2024 5:49 pm

As opposed to, say... other galaxies?
I'm not sure what you mean by that. That other galaxies have only been observed by a small percentage of all humans who have ever lived? That's true of course, but other galaxies might still be more properly deemed "APOD"s where the "A" stands for "astronomy" instead of "atmospheric" (at least according to the OP).
Just pointing out that there is nothing remotely "unique" in astronomical phenomena that have only been observed by a tiny percentage of all humans who have ever lived!
I think the OP was arguing that atmospheric phenomena of all types are much more commonly observed by humans than astronomical phenomena, and so are more worthy of being APODs. Or at least that's what I think was being implied.
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Re: APOD: A SAR Arc from New Zealand (2024 Jan 03)

Post by Chris Peterson » Wed Jan 03, 2024 6:35 pm

johnnydeep wrote: Wed Jan 03, 2024 6:29 pm
Chris Peterson wrote: Wed Jan 03, 2024 6:22 pm
johnnydeep wrote: Wed Jan 03, 2024 6:12 pm

I'm not sure what you mean by that. That other galaxies have only been observed by a small percentage of all humans who have ever lived? That's true of course, but other galaxies might still be more properly deemed "APOD"s where the "A" stands for "astronomy" instead of "atmospheric" (at least according to the OP).
Just pointing out that there is nothing remotely "unique" in astronomical phenomena that have only been observed by a tiny percentage of all humans who have ever lived!
I think the OP was arguing that atmospheric phenomena of all types are much more commonly observed by humans than astronomical phenomena, and so are more worthy of being APODs. Or at least that's what I think was being implied.
I'm just taking it as it was written. A complaint about auroras not being "astronomical" enough (which is a reasonable opinion) followed by a very odd assertion.
Chris

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Re: APOD: A SAR Arc from New Zealand (2024 Jan 03)

Post by johnnydeep » Wed Jan 03, 2024 7:45 pm

Chris Peterson wrote: Wed Jan 03, 2024 6:35 pm
johnnydeep wrote: Wed Jan 03, 2024 6:29 pm
Chris Peterson wrote: Wed Jan 03, 2024 6:22 pm

Just pointing out that there is nothing remotely "unique" in astronomical phenomena that have only been observed by a tiny percentage of all humans who have ever lived!
I think the OP was arguing that atmospheric phenomena of all types are much more commonly observed by humans than astronomical phenomena, and so are more worthy of being APODs. Or at least that's what I think was being implied.
I'm just taking it as it was written. A complaint about auroras not being "astronomical" enough (which is a reasonable opinion) followed by a very odd assertion.
Ok. Perhaps the OP will clarify.
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Jim Armstrong

Re: APOD: A SAR Arc from New Zealand (2024 Jan 03)

Post by Jim Armstrong » Wed Jan 03, 2024 9:46 pm

My, look at all the replies.
My first point is pretty plain: I think that aurorae take place in the atmosphere, part of Earth. Astronomy is for things that take place in space, not of Earth.
My second point probably should have begun: "Whether atmospheric or astronomical..."
I have always been struck by the fact that aurorae can be seen only from places on Earth where few people live.
I have only seen the aurora borealis one time and as a dim, short-lived distant glow lacking spectacularity.
Searching aurora on APOD gives about 3500 hits.
Maybe that is justified since photos are the only way 90%+ of us will ever see them in person.

Roy

Re: APOD: A SAR Arc from New Zealand (2024 Jan 03)

Post by Roy » Wed Jan 03, 2024 10:10 pm

Well , I saw a sky full of Aurora Borealis once, in Massachusetts. The sun had put out a larger than usual flood of electrical particles, about thirty years ago. That’s about what, 42 degrees North Latitude? The papers mentioned it ahead of time, so we could go out and look for it.

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Re: APOD: A SAR Arc from New Zealand (2024 Jan 03)

Post by johnnydeep » Wed Jan 03, 2024 11:20 pm

Jim Armstrong wrote: Wed Jan 03, 2024 9:46 pm My, look at all the replies.
My first point is pretty plain: I think that aurorae take place in the atmosphere, part of Earth. Astronomy is for things that take place in space, not of Earth.
...
So, what about a meteor? That phenomenon takes place in the atmosphere, but it is caused by something originating in space - just like aurorae! Should meteors be APODs? Plenty have been featured over the years, both singularly, like Chelyabinsk over Russia, and showers, like the Geminids.
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"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}

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Re: APOD: A SAR Arc from New Zealand (2024 Jan 03)

Post by Chris Peterson » Thu Jan 04, 2024 12:12 am

Jim Armstrong wrote: Wed Jan 03, 2024 9:46 pm My, look at all the replies.
My first point is pretty plain: I think that aurorae take place in the atmosphere, part of Earth. Astronomy is for things that take place in space, not of Earth.
I think that's a pretty obsolete position... one that stems from an ancient Earth-centric view. We now understand that Earth is just another planet, but one we have immediate access to. Not unlike the way that the Sun is just another star, but one we can examine much more closely. Auroras occur on other planets than Earth, both in the Solar System and in other planetary systems. They are precipitated by energetic events in the Sun, as well as in other stars. We understand what is going on with those other planets and stars because we can examine our own.

And the fact is, an aurora is an example of our atmosphere and magnetic field acting as a type of sensor that informs us about the activity of the Sun, without needing to place instrument in space or near the Sun.

There may well be good reason to argue that aurora images on APOD don't teach us much, and come at the expense of much more informative images. But to claim that they aren't astronomical is, I think, just incorrect.
Chris

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RET

Re: APOD: A SAR Arc from New Zealand (2024 Jan 03)

Post by RET » Thu Jan 04, 2024 4:57 pm

was taken earlier this month
could be 'last' month, according to photographer's Instagram.