Wow Gerhard,
This is too cool! I was going to do this with
Heavens-Above but it just seemed to cumbersome. So
about the *difference* between the amount of sunshine,
twilight, and darkness at the poles and arctic circles
- do you suppose this has to do with the Earth's
aphelion and perihelion differences?
Regards,
Jeff Umbarger
Plano, TX USA
--- Gerhard HOLTKAMP <grd.holtkamp@t-online.de> wrote:
>
> A few months ago (having had nothing better to do at
> the time) I calculated
> the total hours of sunshine and various twilights
> for different latitudes in
> 2005. The Northern Arctic Circle came out first with
> sunshine hours (4647 h).
> The North Pole had 4575 h, the equator 4422 h, the
> Southern Arctic Circle
> 4530 h and the South Pole 4387 h. (Sunshine being
> defined as the upper limb
> of the sun still visible with refraction.)
>
> The maximum of civil twilight hours (the center of
> the sun being higher than
> -6 degrees) was at 69 deg north with 5513 h (and not
> at the artic circle with
> 5487 h). The North Pole showed 5212 h, the equator
> 4684 h and the South Pole
> 5031 h.
>
> If it comes to the total hours of perfectly dark sky
> (sun below -18 deg and no
> moon) the worst was 80 deg North with just 801 h
> (the North Pole had 829 h).
> You could enjoy 1788 h at the equator and 1066 h at
> the South Pole. (Of
> course your total darkness at the poles would
> further get disturbed by
> aurorae!)
>
> Ironically, although the equator is best for dark
> skies it seems to be less
> favorable for visual observations of low flying
> satellites due to the short
> twilight there and also due to the fact that polar
> orbiting satellites are
> converging over the polar regions and can be
> observed more frequently there.
> So pick your favorite satellite observation spot!
>
> Gerhard HOLTKAMP
> Darmstadt, Germany
>
>
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