Astronomical Twilight ! !

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Astronomical Twilight ! !

Postby pscammp » Fri Jul 03, 2015 1:58 pm

Ok everyone, was not sure where to post this so I figured here would be a good enough place !

Take a look at the chart in the bottom part of the following page:

http://astro.ukho.gov.uk/nao/miscellanea/birs2.html

Now someone might be willing to enlighten me but im confused to hell about
the ' **-** ' where astronomical twilight begins and ends

' **-** ' meaning the phenomenon doesn't occur ?????

The way I understand the text is that Astronomical twilight begins once the center of the sun
drops 18 degrees or more below the horizon. Well, here in the south of England UK I can watch
the sun touch the horizon, some time later it completely disappears below the horizon, then It
goes all the way around the earth and rises in the east the next morning ! ! !

How can this chart not give a time when it hits and passes 18 degree's below the horizon when it
clearly does. I can fully understand it not managing this in the north pole etc.

Is there something im missing here ????

Many Thanks ow intelligent ones

Paul

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Re: Astronomical Twilight ! !

Postby julianr » Fri Jul 03, 2015 2:14 pm

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Re: Astronomical Twilight ! !

Postby galileo » Fri Jul 03, 2015 3:09 pm

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Re: Astronomical Twilight ! !

Postby carastro » Fri Jul 03, 2015 4:46 pm

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Re: Astronomical Twilight ! !

Postby pscammp » Fri Jul 03, 2015 7:53 pm

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Re: Astronomical Twilight ! !

Postby carastro » Sat Jul 04, 2015 9:48 am

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Re: Astronomical Twilight ! !

Postby Silversmith » Sun Jul 05, 2015 10:19 am

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