APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Comments and questions about the APOD on the main view screen.
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alter-ego
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Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by alter-ego » Mon Sep 30, 2013 6:08 am

The affect is high up, beyond the cloud cover that shows up at the end.
Based on the cloud-like drift and modeled appearance, I'm betting on air glow.
The air-glow example below looks very similar.
Click to play embedded YouTube video.
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Steven

Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by Steven » Mon Sep 30, 2013 6:14 am

probably a daft idea but since its really early in the morning, could it be a green light from the sun. On very rare occasions the sun can be green. Could it be this light shining on the underside of the clouds as the sun might be close to the horizon, perhaps even slightly below the horizon, from the viewers position?

Curt

Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by Curt » Mon Sep 30, 2013 6:19 am

totoleg wrote:
Curt wrote:My guess is the light source that is hidden behind the foreground rock, illuminating the other rocks with a greenish hue, is then reflecting off the incoming tide water, and illuminating the bottoms of the low clouds (fog) hovering just above the waters.
i agree with your observation, curt. i just like to add that probably the light source hidden behind the rock was placed in order to illuminates other rocks in order to give/contribute artistic effect on the video, however, it accidentally or unintentionally light-up the incoming low clouds.
Yes, totoleg, I too assume the light source was placed by the photographer.

Spock

Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by Spock » Mon Sep 30, 2013 6:24 am

After burn from an Alien craft travelling at just below light speed.

DavidGovett

Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by DavidGovett » Mon Sep 30, 2013 6:24 am

Green flash at sunset?

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Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by Starmon » Mon Sep 30, 2013 6:25 am

This is airglow, you can see that it is beyond the whisp of clouds that roll in. In fact you can also see it formed in gravity waves. A friend of mine took a beautiful skyscape of this same effect: http://www.astroarn.com/nightscape/h2f08a752#h2f08a752
Last edited by Starmon on Mon Sep 30, 2013 6:39 am, edited 2 times in total.
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Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by stephen63 » Mon Sep 30, 2013 6:31 am

Curt wrote:My guess is the light source that is hidden behind the foreground rock, illuminating the other rocks with a greenish hue, is then reflecting off the incoming tide water, and illuminating the bottoms of the low clouds (fog) hovering just above the waters.
I think you're exactly right. The low layer of fog would have a similar effect as light reflecting from the ceiling of an indoor pool. Notice how the reflection off of the fog rolls in perpendicular to the cloud direction. 30 second exposures should be long enough to pick this up with a fast ISO.

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Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by alter-ego » Mon Sep 30, 2013 6:38 am

Nitpicker wrote:Seems to be looking about NE (based on sky motion) from a latitude of N46. Can Aurora Borealis be observed from so far South?
The view is southward, and yes aurora can be viewed well from that latitude.
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Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by Ann » Mon Sep 30, 2013 6:46 am

alter-ego wrote:The affect is high up, beyond the cloud cover that shows up at the end.
Based on the cloud-like drift and modeled appearance, I'm betting on air glow.
The air-glow example below looks very similar.
Click to play embedded YouTube video.
This airglow thing is confusing to me. I've never heard about it until the last few years. Has airglow become much more common lately? Has man-made pollution something to do with it?

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Ahmad

Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by Ahmad » Mon Sep 30, 2013 7:05 am

I am thinking of a HDR (High Dynamic Range imaging) -tone mapping side effect: it seems clears that the high definition colors of each image in the video indicates that each image was shoot something like 3 times (or more). Then using HDR, they remap the colors with high range effects. In that case, simple haze forming over the sea could be mapped to another color than its natural tone, e.g. green as it is here, according to the choice of the photographer when he effected his HDR on the computer.

rdchdwck

Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by rdchdwck » Mon Sep 30, 2013 7:18 am

Compare the Earth Science Photo of the Day for September 30, 2013--same green just brighter.

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Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by Nitpicker » Mon Sep 30, 2013 7:24 am

alter-ego wrote:
Nitpicker wrote:Seems to be looking about NE (based on sky motion) from a latitude of N46. Can Aurora Borealis be observed from so far South?
The view is southward, and yes aurora can be viewed well from that latitude.
Right you are. I live too close to the tropics and the heat is getting to me. I assumed (which is often a bad idea) that the camera would be pointing roughly towards Perseus.

Air glow now sounds more plausible to me than algal luminescent reflections. Thanks for the education (twice).

Excoriator

Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by Excoriator » Mon Sep 30, 2013 7:25 am

It is a pity two cameras had not been used to eliminate the possibility of camera artifacts as previously discussed. Had both cameras shown the same thing however, I'd put my money on the aurora. Are there not satellite records of aurora activity which could perhaps show activity at the time an place where the video was made?

ebachu

Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by ebachu » Mon Sep 30, 2013 7:26 am

This looks to me like an aurora caused by the Earth's magnetic field similar to the Northern lights.

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Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by Great White North » Mon Sep 30, 2013 7:36 am

I have seen that often in northern Alberta. It can be recognized by it's wave like motions. It is Aurora and yes it can be seen that far south. This could be authenticated by checking for solar activity preceding this event.

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Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by akwaugh » Mon Sep 30, 2013 7:49 am

I'm no scientist but it looks like an aurora, possibly excited oxygen atoms? I read it up and they can give a green glow.
As for other comments solar activity will be the obvious thing to look for particularly as we have a solar maximum just now.
I doubt it's reflections from the sea as (low/visible) clouds didn't appear until the last few frames and they were travelling in a different direction.

(I'm addicted to APOD - great work people, keep it up!)

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Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by Hill » Mon Sep 30, 2013 7:56 am

I originally replied to your G+ post. Below is a duplicate of that reply.

Just north of the rocks is The Rocks Provincial Park. Google street view shows this to be a fairly large area that is possibly well lit at night. I think the green glow is a layer of thin low clouds that was illuminated by greenish light from the park. The light is green because of park lights shining on extensive grass and vegetation in the park, which reflected back on the cloud layer giving them a greenish hue. At the very end an even lower layer of clouds moves in totally obscuring the sky. These lower clouds were probably low enough to be fog at the campground and therefore not produce a greenish color.

In this screen capture >> http://img42.imageshack.us/img42/9982/iefj.jpg << from Google earth street view you can see five of the clusters of floodlights at the park.

Silvernow

Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by Silvernow » Mon Sep 30, 2013 8:10 am

It appears to start as an emanation from the trees on the large rock straight ahead

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Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by fzz » Mon Sep 30, 2013 8:12 am

I don't think it is likely to be light reflected off clouds or mist. The view is southerly, and the glow appears to move from east to west. But right at the end you can see a few wisps of cloud blowing to the east, and Weather Underground's weather history indeed shows the winds were southwesterly the whole night in New Brunswick.

The glow in the sky seems to coincide with the rocks in the foreground starting to be illuminated. Not sure if you can conclude anything from that though.

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Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by gwrede » Mon Sep 30, 2013 8:15 am

Being from the North, I think this simply is aurora borealis. Nothing fancier nor more complicated.

As I see it, the first clouds come at 33 sec, and before that, there's no occultation or dimming of stars that would coincide with the patchiness in the green area. That is one of the hallmarks of aurora borealis, especially when you are standing out there explaining to somebody who's never seen them before.

While most pictures on the net show spectacular, vivid and lively aurorae, the unremarkable ones are very common, too.
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Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by neufer » Mon Sep 30, 2013 8:50 am

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Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by pmersa » Mon Sep 30, 2013 9:02 am

Well, I think we would need to know more about the camera and photo set up. What is the type of camera and filters used? What is its sensitivity curve? And we certainly should know more details about the artifitial illumination used: direction, intensity, distance and, most important, the wavelength coverage. To me, it seems all "too green" to start with (the rocks, the trees). And, funny, the sky looks too red at the beginning (Galaxy area, etc.). In fact, this is the most light-polluted area of New Brunswick (see, for example, http://eoimages2.gsfc.nasa.gov/images/i ... 0x6750.jpg). So, it starts to become very probable that this is indeed human-made illumination. Note that it was Sunday night (well, already Monday early hours when the movie finishes), mid-summer... so, no nearby disco pointing one of those coloured beams up to the sky? Furthermore, there are four coincidences that suprise me: 1) the green lights appear at the same time the tide gets higher; in fact, they almost seem to mimic each other; 2) as the tide fills the area with water, did the artifitial light get covered? This is what it looks like, since the higher the tide grows, the less flare is reflected from the water and (funny) the less green light there is in the sky; 3) the green light disappears and immediately some low clouds appear from the right, moving fast, blown by the wind; 4) the green light only appears at the very end of the video which shuts down shortly after - why? Was this automatic? Was this human intervention? Why at 3am? We still had quite a night to go...

As a sum up, I point for a totally human made green light, intentionally or non-intentionally. It seems to low to be auroras (more consistent with light reflected off low clouds, which are indeed present as it is immediately confirmed aftewards).

Cheers,

Pedro Augusto

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Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by neufer » Mon Sep 30, 2013 9:23 am

Click to play embedded YouTube video.
Hopewell Rocks below: Bay of Fundy green trees
  • Double reflection of clearly observed[/size]
    but shielded from sea artificial lights off of:

    1) Bay of Fundy green trees

    [list]and then...
2) low morning mist.[/size][/list]
http://o.canada.com/2013/09/16/new-brunswick-puts-the-fun-in-the-bay-of-fundy/ wrote:
<<Few place illustrate the incredible height of Fundy’s tides than the iconic flowerpot islets known as the Hopewell Rocks. These tree-topped sandstone towers look like something from a Dr. Seuss book when the tide recedes. When the waters are high, they look like tiny islands off the shore, but when the tide is low, they rise from the sea floor like top-heavy rocks that defy gravity. The water can rise as much as 16-metres so be sure to consult tide tables before you visit.>>
http://en.wikipedia.org/wiki/Bartholomew_and_the_Oobleck wrote:
Image
<<Bartholomew and the Oobleck is a 1949 book by Dr. Seuss (Theodor Geisel). Geisel said he drew inspiration for the book from a conversation he overheard while stationed in Belgium during World War II. During a rainstorm, one of his fellow soldiers remarked, "Rain, always rain. Why can't we have something different for a change?"

The book opens with an explanation about how people in the Kingdom of Didd still talk about "The year Ted Cruz The King got angry with the sky," and how Bartholomew Cubbins, King Derwin of Didd's page boy, saved the Kingdom. Throughout the year, Bartholomew sees the king getting angry at rain in spring, sun in summer, fog in autumn, and snow in winter. The king explains he's angry because he wants something new to come down from the sky, but when Bartholomew points out that "even kings can't rule the sky," the king vows to prove Bartholomew wrong.

One spring night, as he's getting ready for bed, the king gets the idea that ruling the sky is the task of his Royal Magicians so he orders Bartholomew to summon them. After expressing his wish to the magicians, they announce they can make something called Oobleck which won't look like the regular weather that the king doesn't want. The magicians soon return to their secret cave on Mount Neeka Tave to make the oobleck. After watching the cave all night, Bartholomew sees the first sign that the oobleck has been made and that it is falling the very next morning. When the king wakes up and sees the oobleck, Bartholomew tries to caution him on how big the falling oobleck is getting, but the GOP king orders Bartholomew to tell the Royal Bell Ringer that today will be a holiday.>>
Last edited by neufer on Mon Sep 30, 2013 10:47 am, edited 1 time in total.
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Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

Post by skywriter » Mon Sep 30, 2013 9:44 am

Nitpicker wrote:Lovely APOD.

As others noted when this video was first submitted, the green patches appear to coincide with the tide rolling in. It was suggested that the green patches were from bioluminescent algae churned up by the tide, and reflected onto the clouds. This sounds most plausible.
Nitpicker's meaning seems to be the most true: haze and/or clouds are reflecting the artifical light-source behind the rock (on the right side) via water's surface! That's all!
A very nice animation btw!