Taking photos of displays...
ethan.dicks at gmail.com
Tue Mar 1 22:36:09 CST 2005
On Tue, 1 Mar 2005 12:46:32 -0500 (EST), der Mouse
<mouse at rodents.montreal.qc.ca> wrote:
> > Man, I have got to get me down to Antarctica some day. I'm sure this
> > is a really stupid question, bit is that greenish glow really what it
> > looks like in real life? Amazing!
> Well, I've never been to Penguin Central. But I spent six months in
> Tromsø, in northern Norway, and while they didn't look green to the
> naked eye, the auroras there were even more spectacular, in some
> respects, than what's in those pictures - in particular, they covered
> far more of the sky.
The example I have on my page just happens to be the first images I
took last year, when it was barely dark enough to see them (2 or 3
weeks past sunset). We did have several sky-covering events over the
winter, but those are difficult to photograph, especially with only a
36mm-equivalent lens field of view (a "standard" panoramic lens is on
the order of 28mm field-of-view, and really wide angle lenses are
around 16-24mm). Many of my photographs are of the intense ribbons we
saw, because the all-sky events would just look like a green wash to
the camera. Those are best experienced rather than photographed.
Also... we are approaching a solar minimum on the sunspot cycle. We
got more events and more aurorae than we "deserved" statistically.
I'm not looking forward to my next visit, as it will most likely be
fewer aurorae than last year.
Location has a *lot* to do with the spread of aurorae, and not just
latitude - relative position to the northern or southern magnetic pole
is important... it's just as bad to be too close to the mag pole as to
be too far south. One of the nice things about the location of the
Geographic South Pole is that the auroral ring (have a look at the
aurorae from space to see exactly what that looks like) passes over
the top of the station right around lunch time.
> I don't know why they didn't look coloured. Perhaps because the light
> level was too low for much colour vision?
That would be the most likely cause. Faint aurorae appear colorless
to the human eye, but are the same color as intense ones - it's all
about quantum levels and photon emission from excited gas atoms.
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