Aurora from Kelso 16th/17th July 2012

Aurora from Kelso 16th/17th July 2012

Photo Information
This aurora from Kelso 16/17th July taking the form of quiet rays.
18/07/2012 - 03:47mikeyscope
CategorySpecialist / Abstract
Shutter Speed30 sec
Aperturef/5
LensN/A
ISO800
Focal Length24mm

alfpics

Link Posted 18/07/2012 - 08:49
Looks great!
Are the rays from the sun not having long set, or something like that?

Andy
Andy

mikeyscope

Link Posted 19/07/2012 - 00:06
Thanks Andy.

No nothing to do with direct sunlight though the Sun is the cause.
The Sun emits charged particles travelling at high speeds and when these particles reach Earth they are channeled down Earth's magnetic field lines. These high speed particles split electrons from atoms in Earth's atmospheric gases Oxygen & Nitrogen in doing so emit light at a particular wavelength ...much like a giant neon sign!

In this case the green at the bottom is Oxygen, sometimes there is a reddish colour above which is the Oxygen/Nitrogen transition layer...then at the top is the Ultra Violet wavelength of Nitrogen.
In very active displays as I understand it free electrons can re-connect with atoms producing wavelengths that turn the display shades of pink to deep red which I have only seen happen twice in many years observing.

So not lit by reflected light ...but rather more like fluorescent tube lighting.

Mike
My Flickr Site

alfpics

Link Posted 19/07/2012 - 09:15
Hi Mike
Thanks for the explanation - very helpful. I thought they glowed without direct sunlight; it was just that these rays are just so straight it made me wonder!
Andy
Andy

mikeyscope

Link Posted 19/07/2012 - 16:33
Andy

Yes that's correct, they glow without direct sunlight but the Sun does fuel the particles that give rise to this fluorescent light show.

The aurora can take many forms, the term for the appearance of the aurora in this photo is 'quiet rays' as they tend to show little movement...just brightening & fading where they form with little sign of drifting against the starry background.

Mike
My Flickr Site

alfpics

Link Posted 19/07/2012 - 18:30
Its ashame that we don't get them (often) this far south (Brighton!)
Andy
Andy
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