Astronomy Picture of the Day -- A Full Sky Aurora Over Norway

NASA ^ | January 03, 2012 | (see photo credit)

[SunkenCiv]

[Credit & Copyright: Sebastian Voltmer]

[SunkenCiv]

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[Bon of Babble]

Thanks for posting this fantastic, fabulous picture!

Amid all the news about holiday killings, political mud slinging and accusations, and dire predictions about 2012, your photo is a welcome respite, a true thing of beauty!!

Truly a nice way to end my evening.

[unkus]

Awesome!

[Noob1999]

bttt

[oldbill]

Highly distorted and compressed horizontally. Stretch it out about twice its width.
You would never see that display for real, although North Norway has the best and most consistent aurora displays.

[SuziQ]

Just gorgeous!

[knarf]

God tripped carrying paint to the shed.

[onyx]

So much green, I’m surprised! Beautiful!

[raygun]

Auroras are result from emissions of photons in the Earth's upper atmosphere, above 80 km (50 mi), from ionized nitrogen atoms regaining an electron, and oxygen and nitrogen atoms returning from an excited state to ground state. They are ionized or excited by the collision of solar wind and magnetospheric particles being funneled down and accelerated along the Earth's magnetic field lines; excitation energy is lost by the emission of a photon of light, or by collision with another atom or molecule:

• oxygen Green or brownish-red, depending on the amount of energy absorbed.

• nitrogen Blue or red. Blue if the atom regains an electron after it has been ionized. Red if returning to ground state from an excited state.

Oxygen is unusual in terms of its return to ground state: it can take 3/4 sec to emit green light and up to two minutes to emit red. Collisions with other atoms or molecules will absorb the excitation energy and prevent emission. Because the very top of the atmosphere has a higher percentage of oxygen and is sparsely distributed such collisions are rare enough to allow time for oxygen to emit red. Collisions become more frequent progressing down into the atmosphere, so that red emissions do not have time to happen, and eventually even green light emissions are prevented.

This is why there is a colour differential with altitude; at high altitude oxygen - red - dominates, then oxygen - green - and nitrogen - blue/red - finally nitrogen: blue/red (collisions prevent oxygen from emitting anything).

Green is the most common color of all auroras. Behind it is pink, a mixture of light green and red, followed by pure red, yellow (a mixture of red and green), and lastly pure blue.

[onyx]

Thank you very much, dear raygun! I think I’ll bookmark this thread right now to save your information so that I can refer back to it. Very much appreciated!!

[momtothree]

Thank you, SunkenCiv! You know how much I love looking at pictures of the Aurora. It is just so mystical and magical. (now I feel bad... I didn’t get you anything).

[ixtl]

To SunkerCiv: Beautiful, but at the same time scary. I know this is silly, but it reminds me of a ‘wall cloud,’ which here in Texas is associated with violent thunderstorms and tornados.

To raygun: Your comment brought back memories. In graudate school, I wrote a paper on the Aurora for an astronomy class. References to the solar wind, magnetosphere etc. all jogged my old memory. I got an “A” on the paper and in the class. (”It ain’t braggin’ if you can do it.”)

[TheOldLady]

Like this, Bill?

[Texas Eagle]

Thanks for my new laptop wallpaper.

The last one was all pixel-y anyway. This is much better.

[left that other site]

You Made My Day.

[aldabra]

Spectacular

[TenthAmendmentChampion]

I thought the aurora would be less spectacular with the low number of sunspots. Maybe not. Gorgeous!

[brytlea]

WOW!

[SunkenCiv]

:’D