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

I'm thinking of going to Iceland. Not the shop, the country. Now, about this
midnight sun, it must only happen certain months of the year? and it must
be dark all day six months after/before the 'midnight sun'? (ie when the
Earth is the other side of the sun). Well, twighlighty, you know.
That must be how it works, right?

--

suave harv wrote:
I'm thinking of going to Iceland. Not the shop, the country. Now, about this
midnight sun, it must only happen certain months of the year? and it must
be dark all day six months after/before the 'midnight sun'? (ie when the
Earth is the other side of the sun). Well, twighlighty, you know.
That must be how it works, right?

Well, Iceland is south of the Arctic circle so it gets dark (twilighty)
for a while during the summer and then the day gets gradually shorter
until late december when we have ca 4 hours of daylight (and a couple
of hours of twilight, the sun is so low on the horizon that there is
still almost daylight for an hour after the sun goes down)
If you want to experience 6 months of daylight and 6 months of darkness
you must go to either the North or the South pole.
The USA, Canada, Greenland, Norway,Sweden, Finland and Russia all
extend to within the Arctic circle, much farther north than Iceland.

In article ,
suave harv wrote:

I'm thinking of going to Iceland. Not the shop, the country. Now, about this
midnight sun, it must only happen certain months of the year? and it must
be dark all day six months after/before the 'midnight sun'? (ie when the
Earth is the other side of the sun). Well, twighlighty, you know.
That must be how it works, right?

More or less. The further north you go the longer the constant
daylight period is. At the arctic circle, you only get it right at
midsummer. At the pole, you get it for six months, followed by six
months of dark: starting at midsummer, the sun just spirals down - one
turn per day - for 3 months until it reaches the horizon, continues to
spiral down out of sight for three months and then back up for three
months until it reaches the horizon again, and then spirals up for
three months until midsummer.

If you assumed the earth's orbit was circular and did a bit of
geometry, you would be able to work out how long the "midnight
sun" lasted for at intermediate latitudes.

-- Richard

Well, Iceland is south of the Arctic circle so it gets dark (twilighty)
for a while during the summer and then the day gets gradually shorter
until late december when we have ca 4 hours of daylight (and a couple
of hours of twilight, the sun is so low on the horizon that there is
still almost daylight for an hour after the sun goes down)
If you want to experience 6 months of daylight and 6 months of darkness
you must go to either the North or the South pole.
The USA, Canada, Greenland, Norway,Sweden, Finland and Russia all
extend to within the Arctic circle, much farther north than Iceland.

Thanks for the response.
I just looked at my globe and I'm amazed how much higher Norway & Sweden
are. I'd have put Iceland higher! (But geography was never my strong point).
I still want to visit Iceland though. I've always had a hankering. Do you
know what times of year are best to see the Aurora there? I daresay I'll be
stopping in Reykjavic.
Bet you've got dark skies there too, a country as big as the UK with a
fraction of its population!

At the pole, you get it for six months, followed by six
months of dark: starting at midsummer, the sun just spirals down - one
turn per day - for 3 months until it reaches the horizon, continues to
spiral down out of sight for three months and then back up for three
months until it reaches the horizon again, and then spirals up for
three months until midsummer.

They say the 'midnight sun' is very disorientating for someone not used to
it. I don't know if it's o/t for an Astronomy group or not, but I find it
fascinating all the same.
Now, I wonder which is the easiest place to fly to from the UK to see the
true 'Midnight Sun', (by easiest, I mean cheapest I suppose. These
'explorers tours' I've seen don't half cost a packet!).

In article ,
suave harv wrote:
a country as big as the UK

Less than half as big.

with a fraction of its population!

That's certainly true. Smaller population than Edinburgh.

-- Richard

Hi suave herv,
suave harv wrote:
[snip: geography]
Thanks for the response.
I just looked at my globe and I'm amazed how much higher Norway & Sweden
are. I'd have put Iceland higher! (But geography was never my strong point).
I still want to visit Iceland though. I've always had a hankering. Do you
know what times of year are best to see the Aurora there? I daresay I'll be
stopping in Reykjavic.

Aurorae can occur at any time of year. However, they are a bit more
common in spring and autumn, since the Earth's orbit crosses the solar
equator, making CMEs more likely to imact us. The skies are typically
quite murky in autumn but mostly clear in spring, which makes spring a
better bet. A strong aurora over snow can be eerily spectacular.

Even if there is an aurora in summer, you won't see it at high
latitudes, because the sky just isn't dark enough. Midnight sun or
midnight twilight will completely swamp an aurora, even a powerful
aurora. I live at 62.9N in Finland, and it does not get any darker than
civil twilight from mid-May to late July. Astronomical twilight will end
on 30 August (tomorrow!) for the first time since 13 April.

Best Regards,
John.

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?

ISTM that northern Finland is probably the best destination, from the
UK, for the Midnight Sun, since Norway is lumpy and more liable to have
a mountain in the way unless one goes to the edge or high up. I've seen
the "all-night daylight" but not the actual midnight Sun, in the
hinterland of Oulu with an excursion to Arctic Rovaniemi.

--
© John Stockton, Surrey, UK. Turnpike v4.00 MIME. ©
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms & links;
Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.

Hello John,

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.

ISTM that northern Finland is probably the best destination, from the
UK, for the Midnight Sun, since Norway is lumpy and more liable to have
a mountain in the way unless one goes to the edge or high up. I've seen
the "all-night daylight" but not the actual midnight Sun, in the
hinterland of Oulu with an excursion to Arctic Rovaniemi.

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.

Best Regards,
John.

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.

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.

--
© John Stockton, Surrey, UK. Turnpike v4.00 MIME. ©
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms & links;
Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.