On Dec 29, 2009, at 10:02 AM, Rick Monteverde wrote:
Horace –
My sighting wasn’t just after sunset, it was just after nightfall
- total darkness. There was just a vague hint of fading light on
the horizon, but the sky surrounding the object, which was
relatively low in the southwest, was already black.
I did find something on the after-sunset atmospheric distortion –
they say add 6 arc minutes to the apparent semidiameter of the sun.
I’ll try to muddle through your figures in a little while. I sure
appreciate the help, thanks.
Yes, that accounts for distortion of the image. There is also
atmospheric scatter involved, and that might make an object look
orange or red. It makes snowy mountains here take on hot pastel
colors - called Alpenglow.
This time of year the sun sets almost due west there. If the object
was ever in a direction approximately due north or south of you, i.e.
on a line perpendicular to the sunset location, then the altitude h I
provided fairly closely applies to the object for that time t in the
table. If it was mainly east or west then another calculation is
needed. I would say anything above 100,000 feet, or 18.9 miles, was
probably not a military jet, and certainly not a passenger jet.
That altitude h corresponds to about 22 minutes after surface
darkness - to whatever degree such darkness needs to be defined.
From experience there, I know it gets dark pretty fast in Hawaii
after sunset - especially compared to here - where sunsets can take a
very long time. 8^) If you observed the object an hour after sunset
then I'd say it was well past the 22 minutes after darkness mark. A
general compass direction thus may be sufficient information for a
definitive answer. That far after sunset, an hour, taken even alone,
is a pretty strong indication it was not an airplane.
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
