Aurora alert: Powerful geomagnetic storm could spark northern lights as far south as Illinois tonight and tomorrow

[Admin]

Aurora chasers are on high alert for powerful geomagnetic storm conditions on Dec. 30 and Dec. 31 with northern lights possible deep into mid-latitudes.

Aurora alert: Powerful geomagnetic storm could spark northern lights as far south as Illinois tonight and tomorrow : Read more

 

[cacarr]

" ... far south as Illinois and Oregon (around 50° latitude). ..."

No part of Oregon is at 50⁰ latitude. Portland is at 45.5⁰ North

 

[ACanadianDude]

The map we saw, via Google, shows 50 degrees to run through Manitoba. The 49th is the boarder between the USA and Canada... Or did the maps change and SPACE. COM forget to tell us all..?

 

[billslugg]

The aurora can be seen far south of where it occurs. If it is 60 km altitude, it could possibly be seen on the horizon 800 km away. An aurora 1,000 km high might be seen 3,700 km away.

 

[Unclear Engineer]

So, how high are auroras actually formed? From https://www.swpc.noaa.gov/content/aurora-tutorial

"The figure below shows a typical spectrum of aurora.

Different auroral colors come from different heights in the atmosphere primarily because the life-time of an excited atom or molecule (time spent in its excited state) is vastly different for different colors of the aurora. The green aurora from oxygen in the 1S state typically occurs from 120 to 400 km (80 to 250 miles) above the surface of Earth. The red aurora from oxygen in the 1D state is restricted to altitudes above 300 km (180 km miles). This is because oxygen in the 1D state has a very long lifetime (>150 sec) and can only survive in the thinner atmosphere above 300 km. At lower altitudes the oxygen in the 1D state collides with other atmospheric atoms or molecules before it can emit a photon which deactivates or quenches the excited oxygen. The 1S state of oxygen has a lifetime of about 1 second and therefore emits a photon more quickly and thus can emit at lower altitudes where the density is higher. The aurora sometimes has a purplish lower border which comes from emissions from molecular nitrogen. This "prompt" emission is emitted from excited states of nitrogen that have almost no delay between excitation and emission. It survives at even lower altitudes between 120 and 200 km (80 to 120 miles). In the video sequence at the end of this readme document, the purple emissions from the nitrogen seems to lead the green emissions from the oxygen. This is an example of the difference between the prompt emission of nitrogen vs the emission from the longer-lived excited state of oxygen." [corrected "km" to "miles"]