View Full Version here: : Aurora Australis 17 th June 2012
18-06-2012, 10:50 AM
Received an Aurora alert last night about 900pm. The K-Index was at 4 and rising,
the sky was cloudy but I took the risk anyway. Drove down to Point Leo Foreshore and setup.
I managed to capture this Image . You could see the aurora with the naked eye but no colour.
Pentax K-x @ iso3200 30 second sub only 14mm F/2.8 lens processed in PS CS2.
Regards Paul :)
Thanks Paul for posting!
Got me googling: how come the naked eye sees an aurora but without color?
From what I understand in the last paragraph, this is due to no photon emission from the excited atoms because, in lower altitudes, they hand over their excitement to their neighboring (e.g. smog-?)atoms, instead.
The reddish glow in your picture is the aurora from lonely oxygen in very high altitudes which can properly emit their excitement through photons. But do so in wavelengths that our visual organs can hardly perceive.
It is also proof that the ozone hole is not above your location.
18-06-2012, 12:36 PM
Very nice, well done. :thumbsup:
18-06-2012, 12:46 PM
Yes an interesting question Silv! As we know the human eye can only see colour within an certain range of wavelength. I have witnessed three rather strong auroras and I certainly saw an brilliant red with one of them.
As for last night there maybe an easy answer. Remember the difference between an emission and reflection nebula? Both regions have excited Hydrogen atoms and the photon release is caused by the electron shifting from its N3 or N2 orbit down to its natural N1 state...releasing a photon as a result. The red we see in the Emission nebula is that actual photon release, but with a reflection nebula they are emission nebulas too but the light is scattered by dust, interstellar medium at el and the wavelength of blue is seen.
Now considering the aurora I think the red and green emission maybe scatttered as well to the naked eye..Certainly there was alot of cloud mositure and the like.
Some other friends of mine imaged lasts night's aurora too and captured a yellow into green into red aurora, but the yellow and green was on the horizon not high above 10 degrees.
As we know different atoms release different colours H,Na and 02 when the electrons move down from their exited state. Maybe the solar flare needs to be up to a certain strength for the aurora to express colours visually?
18-06-2012, 12:50 PM
Yes, I noticed a huge area yesterday when I checked:-
It had been quite modest for a few weeks, as I recall. Then suddenly! Wished I was in southern Tassie last night (cloud permitting!)
18-06-2012, 12:51 PM
Awesome to view let lone capture the colours, Must be wrapped with that Paul , Very Nice Show !
18-06-2012, 12:53 PM
:) Very very cool.
Ah, yes, Paul - there is a similarity between the nebulae you describe and the aurora.
As explained in the link, with auroras, it's the photons emitted from excited oxygen (green in low + red in high altitudes, the latter less observable to human eyes)
and nitrogen (blue and pink).
And for both elements:
the more distraction from neighboring atoms (pollution, clouds), the less photons are emitted.
So intriguing - a whole new world of knowledge is opening a little gate via your posted image.
18-06-2012, 02:55 PM
I saw this one last night too (nicely captured Paul):
I was getting ready to crash for the evening and by chance clicked on Ovation/Aurora/South -
Hmm, K=5 and lots of colour - Had not seen that on this site before.
So I went outside (rural ~36.7 South) and the whole southern sky was aglow to about the SCP.
Visually it appeared a very very pale green, though this may well be an illusion.
It pretty much washed out the small amount of Melbourne skyglow we get on our Southwest Horizon in magnitude but made it appear much more golden than usual. This is maybe why the Aurora looked pale green to me.
When I have observed Aurora at these latitudes in the past, it was often preceded by this lighting of the sky.
The good ones I have seen in the past all had pillars, shafts and regions aglow with crimson, most of this activity was about the altitude of the SCP or a bit higher.
Wanted to go out later for another look but had to crash for an early start in the morning. Oh well, maybe next time - but it is definitely a breathtaking and memorable site to behold.
18-06-2012, 03:34 PM
Thank you everyone for your kind comments.
Silv yes it is great when the science comes into it. I am reading my wife's astronomy text book called "Universe" 8th edition and explains it rather well.
I usually do about 1000 images and use "Virtual Dub" to create a video.
The weather was rather hit and miss so I didnt bother, but the images I did take (about 20) did show a large pillar dancing across the sky.
Erick thank you for the fantastic link too :thumbsup:
Regards Paul :)
19-06-2012, 08:45 AM
Great capture Paul.
19-06-2012, 06:09 PM
Visible from my location (Port Huon, Tasmania) on a couple of occasions recently. No colour to speak of, initially it looked like a sky glow from a nearby town but there are no towns of any size south of me.
Hope for more tonight, it's certainly cold enough!
20-06-2012, 07:19 PM
Great stuff, Paul! My shots of the Aurora Borealis were primarily green. My suspicion is that most images of the Aurora Australis are taken from much further away and so they tend to show more of the red from atomic oxygen higher in the atmosphere.
I have just realised I have an image of the aurora too.
I was shooting a LMC & SMC widefield on Sunday night/Monday morn and ended up with a very deep red hue, I couldn't work out what happened, but now I know!
21-06-2012, 09:29 PM
Very pretty Paul!
21-06-2012, 10:06 PM
Funny when you take an image of the night sky, you never know what shows up!
I have been chasing Auroras thanks to two good friends of mine, Alex Cherney and Greg Walton.
The only problem is I usually get a phone call around 1100pm telling me an Aurora is occurring.
Still the natural beauty is well worth the effort.
Thank you everyone for your encouraging comments.
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