Re: [APML] Aurora Colors

[Mark Kaye <mark.kaye@sympatico.ca>]

>I read somewhere what causes each aurora color but of course I lost it. Does
>anyone here know what each color represents, which ionized gas, level of
>ionization, exact emission lines? I have never seen a white aurora, is this
>just red green and blue all together?

    When Matt gets his "Observer's Handbook" for joining the Royal 
Astronomical Society of Canada, he too will be able to look this 
information up on page 86.  There is a section on aurora and in the article 
it give the colours and what causes them.  "Aurorae can appear green or 
red, although if they are faint, the eye cannot respond to the colour and 
they appear grey.  The greenish colour is due to spectral lines from oxygen 
(558nm) and a range of lines from nitrogen covering the band 391 to 
470nm.  Under highly disturbed conditions, red spectral line emissions at 
630nm and 636nm and in a series of bands between 650 and 680nm can also be 
seen.  The green emissions are produced at a height of about 110km.  The 
red, 630 and 636nm emissions, due to atomic oxygen, originate at heights 
between 200 and 400km; the 650 to 680nm emissions are produced at about 90km."
    It then goes on to say to go to page 27 for the exact spectral lines 
which are:  N2+, blue, 465.2nm; O, yellow-green, 557.7nm; O, red, 630nm; 
and O, red 636.4nm.
    Clear skies!
                MK

http://www3.sympatico.ca/mark.kaye/


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