"Adrian D. Shaw" wrote in message
...
Felly sgrifennodd Roger Smith :
Astronomical twilight does not end until the sun is 12 deg below the
horizon, so at the summer solstice it lasts all night at latitudes north
of
54.5 deg.

Unless definitions have changed, I think that's a little confused.

Civil twilight: 0-6 degrees below
Marine twilight: 6-12 degrees below
Astronomical twilight: 12-18 degrees below

Even the Lizard peninsula experiences astronomical twilight all night at
this time of year (by about 1.5 degrees). Gianna gets marine twilight all
night (sun is about 9 degrees below) and shetland gets civil (terrestrial
I think I read it as) twilight all night.

When I lived between Aberdeen and Peterhead, I remember walking on Forvie
Sands at midnight (local: i.e. about 1:08 am). A full moon was shining,
but
based on the shadow cast, the full moon was giving less light than the
sun.

Adrian

--
Sorry Adrian, my mistake - carelessness, not ignorance. All of the UK (ie
anywhere north of 48.5 deg) is afflicted by this phenomenon at this time of
year.

Regards, Roger