APOD: Red Aurora Over Australia (2012 Feb 01)

[APOD Robot]

Red Aurora Over Australia

Explanation: Why would the sky glow red? Aurora. Last week's solar storms, emanating mostly from active sunspot region 1402, showered particles on the Earth that excited oxygen atoms high in the Earth's atmosphere. As the excited element's electrons fell back to their ground state, they emitted a red glow. Were oxygen atoms lower in Earth's atmosphere excited, the glow would be predominantly green. Pictured above, this high red aurora is visible just above the horizon last week near Flinders, Victoria, Australia. The sky that night, however, also glowed with more familiar but more distant objects, including the central disk of our Milky Way Galaxy on the left, and the neighboring Large and Small Magellanic Cloud galaxies on the right. A time-lapse video highlighting auroras visible that night puts the picturesque seen in context. Why the sky did not also glow green remains unknown.

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[Mactavish]

The video is extaordinary! Brilliant!

[Beyond]

It didn't have much green in it because Aussies do things differently down there. After all, who else has Kangaroos

[Madaya]

Maybe...Protons in - Protons out. Most of the aurora I've seen from down under
have a strong reddish colour (lat approx -33 deg). Is there an actual colour rating
system and any stats on colour?

[Boomer12k]

If you look at the lower left of the Milky Way, the dark dust, if you look at it right, looks like an EAGLE with its wings spread out, and lower to the right, it looks like a FISH in its mouth....

Is it Red in the South, and Green in the North? or is it something else that explains the Red Color of this one....difference in the level of "excitation"???

:---[===] *

[K1NS]

This photo gave me a thought I have never had before, unrelated to the photo.

Can you imagine what the Milky Way must look like to astronomers in the Magellanic Clouds? The night sky is almost filled with a huge spiral galaxy. What a glorious sight that must be. And imagine the constellations, legends and stories that those peoples would have developed in their primitive days to explain the beautiful patterns.

And now for the pedantry. The caption says "picturesque seen." I think it should be "picturesque scene."

[orin stepanek]

The caption says "picturesque seen." I think it should be "picturesque scene."

Or maybe the picturesque scene was seen! Just kidding.

[orin stepanek]

I noticed in the vimeo that some of the higher parts of the aurora appeared red. Maybe it's an altitude thing! http://apod.nasa.gov/apod/ap110328.html

[ashogun]

Anyone have an idea what the bright line on the horizon center is? A ship, city, setting moon?
cheers, Gary

[Byork]

Aurora generally colored blue and green in the northern hemisphere and red in the southern hemisphere ..! Very good point. Phenomenon probably has a lot to do with behavior of particles in different polarity. Electrons dance in the north pole while protons show up in the south pole. CO2 also seems to have an affinity for the south pole seeing as how the southern polar region of Mars is home to CO2 ice.

[RJN]

Added rollover. Fixed stuff. Sorry for the late additions. - RJN

[terrastro]

Thanks for the compliments everyone - much appreciated.

Could it just be that lower altitude green-coloured aurorae are hidden below the horison and that's why we see predominantly red? Green can be seen from further south in Tasmania and South Island of New Zealand.

Visually the Aurora on 22nd did not have any significant colour and appeared as columns of grey/blueish light moving slowly across the southern sky. It was my first visual Aurora and I was overwhelmed with emotions.

Alex Cherney

[starstruck]

Congrats Alex, it's a gorgeous shot. I was wondering about how this view must have looked to the unaided eye, but I think you kind of just answered that. Without knowing any of the exposure details for this image, I should imagine the camera has really brought out the colour and detail. The Milky Way in the southern hemisphere looks really bright and, coupled with the red glow of the aurora, it's a beautiful sight.

[terrastro]

Congrats Alex, it's a gorgeous shot. I was wondering about how this view must have looked to the unaided eye, but I think you kind of just answered that. Without knowing any of the exposure details for this image, I should imagine the camera has really brought out the colour and detail. The Milky Way in the southern hemisphere looks really bright and, coupled with the red glow of the aurora, it's a beautiful sight.

Thanks!

The exposures in the time lapse were 30 seconds, ISO3200, f/2.8 with Nikon D700 and Sony NEX5N, both at 14mm. The still image featured on APOD is just a single frame with Nikon D700 and same parameters.

Alex

[spudcon]

Time lapse movie was the best I've seen, and the music was excellent also. I seldom see auroras here, it seems solar storms usually cause cloudy skies here.

[Chris Peterson]

Auroras generally colored blue and green in the northern hemisphere and red in the southern hemisphere ..!

Not so. Aurora are typically green near the poles, and when energies are high enough to push the auroral oval down to lower latitudes, red is sometimes seen there. It doesn't matter which hemisphere this occurs in.

[neufer]

Auroras generally colored blue and green in the northern hemisphere and red in the southern hemisphere ..!

Aurora are typically red at very high altitudes and green at lower altitudes.

These aurora are so far away from the observer that the low altitude green colors
are below the horizon (or, at least, absorbed by the troposphere).

[size=150]Red and green aurora in Fairbanks, Alaska.[/size]

---

<<Oxygen is unusual in terms of its return to ground state: it can take three quarters of a second 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, then finally nitrogen blue/red when collisions prevent oxygen from emitting anything. Green is the most common 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.>>

[FloridaMike]

Added rollover. Fixed stuff. Sorry for the late additions. - RJN

Thank you for all you do.

[saturn2]

Red Aurora and others objects in the sky.
This image is very good. The proyection is very good, too.

[TNT]

Now here's a change...an aurora australis instead of a borealis. Interesting.

[Dan]

Does anyone know what the orange line in the center of the horizon is?

[Wolf Kotenberg]

If this was a negative, would you spot more details ?

[Guest]

Does anyone know what the orange line in the center of the horizon is?

it's a ship

[BobStein-VisiBone]

<<Oxygen is unusual in terms of its return to ground state: it can take three quarters of a second 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.

Where is the thumbs-up button? Thanks, Alfred E. Neufer, this is what I came here to find out.

[wolf kotenberg]

Is it possible to " git " a picture like this for us in the northern latitutes ? Maybe a poster size ?