The 'midnight sun' - how's it work?

Hello John,
Dr John Stockton wrote:
JRS: In article , dated Tue, 30
Aug 2005 23:48:15, seen in news:uk.sci.astronomy, John Shakespeare
posted :

Dr John Stockton wrote:

JRS: In article , dated Mon, 29
Aug 2005 22:15:55, seen in news:uk.sci.astronomy, John Shakespeare
posted :


I live at 62.9N in Finland, and it does not get any darker than
civil twilight from mid-May to late July.

Have you, then, been able to see the Circumpolar Moon?

Not exactly, if you mean the moon staying above the horizon for a whole
day. I suspect you'd have to go a little further north to see it exactly
to the north. However, I have seen it fairly close to north, especially
near full moon in recent winters. The precession of the line of nodes
was probably more favourable for this a couple of winters ago, when full
moon was at its greatest altitude near mid-winter.


According to what I have read, the Moon will almost be visible from
Muckle Flugga on Wednesday 2006-04-05 at 05:11:36 UTC; and you are a
couple of degrees North of that.

I just checked and you are correct: the moon will stay above the
theoretical horizon here from 06:05 on 2 April 2006 to 06:52 on 6 April
2006. It will only be a couple of degrees above the horizon at some
times in that period, so its visibility may be restricted by surface
topography, forest and other obstacles.

It's a pity that we seem to have nothing from (if there any) relevant UK
professional astronomers, who must have the necessary data.



The town of Rovaniemi is just a few kilometers south of the official
arctic circle, but its airport straddles the line. Of course, there is
midnight daylight further south around midsummer. At our cottage
(61.5°N), you can go out in the fields at "night" and read a newspaper
in the bright twilight during much of June and early July.


I drove there; no doubt my navigator, Malcolm of Oulu, attended to that
detail. ISTR some form of shop on a northbound road, on the Circle
itself.

Yes. It's quite well marked with a big signpost. As far as I recall,
there is also some indicator of the movement of the circle due to
precession, just outside the terminal of Rovaniemi airport.

Did you remember to stay up until 01:00 to see the real midnight sun?
Daylight savings time (a really worthless inconvenience in Finland, BTW)
biases the clock time by an extra hour from solar time, so solar
midnight in summer is around 1 AM.

Best Regards,
John.

JRS: In article , dated Wed, 31
Aug 2005 23:54:41, seen in news:uk.sci.astronomy, John Shakespeare
posted :

Did you remember to stay up until 01:00 to see the real midnight sun?
Daylight savings time (a really worthless inconvenience in Finland, BTW)
biases the clock time by an extra hour from solar time, so solar
midnight in summer is around 1 AM.

No : Rovaniemi was a day trip, and in mid-July. But we did experience,
probably beside Lake Jakalamiemi, the "I wonder if it's bedtime yet?
Ooh, it's tomorrow morning already" effect.

If there had not then been Summer Time in Finland, the clock in the
Stockholm-Turku ferry would in Summer have needed only mono-furcated
hour hands. It must be helpful to have a non-varying difference in time
from the neighbours (bar (briefly) one).

From 2007, US DST will be 2nd Sun Mar to 1st Sun Nov. Canada, Mexico ?

Jeremiah Horrocks also lived in Cambridge - see new book, "The Transit
of Venus".

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