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03-18-2008, 01:02 PM
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Temporarily good natured
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Join Date: Oct 2006
Location: Lots of sun and palm trees with occasional hurricane :)
7,644 posts, read 4,153,386 times
Reputation: 6445
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Rance - why do those northern lights look green? Please don't hit me if that's a REALLY dumb question.
Also, what's that to the left of the 2nd pic- all red and cloudy. A fire? 2nd REALLY dumb question.
Thanks.
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03-18-2008, 01:12 PM
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Livin Life Down A Long Dirt Road
Status:
"Hangin in Naptowne..."
(set 14 days ago)
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Join Date: Sep 2006
Location: I live in Alaska but my heart is in Sweden
10,840 posts, read 8,682,525 times
Reputation: 7949
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I'm not real sure what affects the colors. These look more of a white in real life and it may be the processing within the camera that makes them look so green. I finally was able to find a decent setting and so some of these last few show the pink that was visible in some.
The big lit up cloud in the one picture is the heat/exhaust coming off one of the central production facilities here where I work. Then the facilities are lit up really well. For safety and spotting polar bears in the dark! 60 some below and so any exhaust is a big cloud.
__________________
People may doubt what you say...but they will believe what you do...
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03-18-2008, 01:25 PM
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Temporarily good natured
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Join Date: Oct 2006
Location: Lots of sun and palm trees with occasional hurricane :)
7,644 posts, read 4,153,386 times
Reputation: 6445
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Yeah! Now that you mentioned it, I see the pink.
Really beautiful. Thanks.
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03-18-2008, 06:21 PM
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Senior Member
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Join Date: Aug 2006
Location: Barrow, Alaska
1,546 posts, read 943,506 times
Reputation: 624
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Aurora, and photography
Quote:
Originally Posted by vpcats
Rance - why do those northern lights look green? Please don't hit me if that's a REALLY dumb question.
Also, what's that to the left of the 2nd pic- all red and cloudy. A fire? 2nd REALLY dumb question.
Thanks.
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Aurora is very interesting phenomenon, caused by energy particles from the sun hitting particles in the earth's atomosphere. The particles become "excited" by the energy, and glow. Nitrogen is what causes the green color and oxygen is what causes the red color. I'm not sure about any other colors. I've seen some very "golden" colored aurora, for example, and in photographs it is very easy to determine that, even though we don't see it, there is a lot of very dark blue color too.
Aurora exists at both poles, and is almost exactly the same at any given moment. It peaks during the months of November and March. The activity is in a fuzzy circle or oval. One effect is that places as far south as Juneau get to see a lot of aurora, and so does much of the central part of southern Canada. But other areas that are equally far south (in the Bering Sea, for example), don't see as much.
http://www.swpc.noaa.gov/pmap/gif/pmapN.gif
The ideal place to observe aurora is in Alaska's Interior, for example around Fairbanks. That is, on a average, right about where the southern edge of the fuzzy band will be, so it is usually seen in the northern sky from Fairbanks. The Interior climate in both November and March usually means crisp cold nights with cloudless skies, which is great for watching the lights.
Here in Barrow we get just about as much auroral activity, but the number of days when the sky is clear enough to see them is limited! Also, the "Northern Lights" in Barrow are usually seen either in the southern sky (when they aren't too active) or in the west when it is moderately active. Only when activity is fairly high do we see much to the north.
Photographing the aurora isn't difficult. A wide angle lens is probably best, and setting the camera for manual control of everything will make it easier. Exposures of 30 seconds will show blurred stars! Due to the earth's rotation they will have "moved across the sky". At 15-20 seconds it isn't as noticable, and with shutter speeds faster than that it won't be obvious at all. Set the camera on a tripod or other solid support, put the focus to infinity, set 20 seconds for the shutter speed, and perhaps f/5.6 or f/8 for the aperture... and click away.
Wider aperture and longer shutter speeds might have different effects than one would expect, depending of whether the display is moving or static. If it is not moving at all, the image will be brighter with a longer shutter speed, but if it's moving the shutter speed will instead just change the area over which it has moved! So the aperture is what sets how bright it is, usually.
If there is any light from ground objects, it will usually show up much brighter than you'd expect (due to the long exposure times, so if that is a problem, try shorter exposures).
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03-19-2008, 09:04 PM
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Natural born citizen
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Join Date: Apr 2007
Location: In the sunshine on a ship with a plank
3,414 posts, read 2,282,486 times
Reputation: 1906
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I visited your beautiful state three years ago- seeing those pictures is giving me the itch to return..... but it'll have to be in the winter so I can see the Northern Lights. Maybe I'll come for the Iditarod or Yukon Quest next year.
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03-19-2008, 11:17 PM
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Visitor from Planet Quatt =^..^=
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Join Date: Oct 2007
Location: Cosmic Consciousness
3,861 posts, read 3,716,007 times
Reputation: 1822
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Quote:
Originally Posted by vpcats
- why do those northern lights look green?
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From the world's leading authority on the Northern Lights, the Geophysical Institute of the University of Alaska at Fairbanks, here's everything you could want to know about the colors of the lights: 
Question #2
Aurora FAQ
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03-20-2008, 09:49 PM
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80 above in the land of midnight sun!
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Join Date: Jul 2007
Location: Fairbanks Alaska
1,675 posts, read 1,672,765 times
Reputation: 480
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Quote:
Originally Posted by pirate girl
I visited your beautiful state three years ago- seeing those pictures is giving me the itch to return..... but it'll have to be in the winter so I can see the Northern Lights. Maybe I'll come for the Iditarod or Yukon Quest next year.
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Plan for next Feburary and Early march, for all three! Best time to see them! Quest ends in Fairbanks next year, and two weeks later you can jump over to Nome for Iditirod. Ice Festival in Fairbanks. Oh yea, fur rondy in Anchorage.
Something to think about.
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03-20-2008, 10:50 PM
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I live in NC but my heart is in Alaska
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Join Date: Jan 2008
Location: Alaska, where women win the Iditarod and men mush poodles!
8,904 posts, read 6,018,638 times
Reputation: 1236
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I'd like to look at the northern lights while soaking in the hot springs.
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03-21-2008, 05:49 PM
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I live in NC but my heart is in Alaska
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Join Date: Jan 2008
Location: Alaska, where women win the Iditarod and men mush poodles!
8,904 posts, read 6,018,638 times
Reputation: 1236
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Quote:
Originally Posted by allforcats
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Thanks! I'll have to see about doing that on the winter trip.
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