Starship Asterisk*

terrastro wrote:I use these two web pages as a guide:
http://www.swpc.noaa.gov/forecast.html
http://www.swpc.noaa.gov/pmap/OverviewS.html

wbd wrote:

terrastro wrote:It was my first visual Aurora and I was overwhelmed with emotions.

Alex Cherney

Awesome imagery Alex, congratulations!

Oh man, I wish I had have known about this. I've always wanted to see an aurora (it's #1 on my 'bucket list') and I only live a few kilometres away from Flinders in the outer SE suburbs of Melbourne!
I always thought I'd have to travel to very northern latitudes - Canada, Scandinavia, etc. - to see one, but here's one in my own backyard and I didn't even know about it.
Is there any way of knowing (weather permitting of course) when and where auroras might be visible and if so, are there any websites that publish such information (I have looked at http://www.iceinspace.com.au a couple of times - would that be the best resource for such information)?

Cheers,
Rohan

Chris Peterson wrote:

Flase wrote:Of course you're also looking through a lot of atmosphere at the horizon. The Sun also appears red.

Yeah, but these colors are produced by narrow emission lines. No amount of atmosphere can make a narrow green line look red- all it can to is reduce the brightness.

terrastro wrote:It was my first visual Aurora and I was overwhelmed with emotions.

Alex Cherney

Flase wrote:Imagine the night sky in a couple of hundred years. Such a timelapse video would look like a web of white lines of satellite paths.
There might even be space stations big enough to see clearly with your naked eye.

Flase wrote:Of course you're also looking through a lot of atmosphere at the horizon. The Sun also appears red.

Scabulus wrote:
It is possible that it did glow green, but the sea level observer couldn't see it because of the curvature of the earth. In the summer, I can see thunderstorms a couple hundred miles away, but I only see the tops. In the time lapse video of the aurora, some green can be observed, but it is concentrated on the horizon. It is possible that during that time the aurora was closer, thus making the green visible to the observer.

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

neufer wrote:

http://en.wikipedia.org/wiki/Aurora_%28astronomy%29 wrote: <<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.

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

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

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

http://en.wikipedia.org/wiki/Aurora_%28astronomy%29 wrote:

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

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<<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.>>

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