OT: Question for the navigators



in message <[email protected]>, Simon Mason
('[email protected]') wrote:

>
> "Tom" <Don'[email protected]> wrote in message
> news:[email protected]...
>> Completely off topic question for anyone on here who has navigation
>> skills.
>>
>> At 2.30 this afternoon, the sun was shining directly in line with the
>> path down the middle of my allotment.
>>
>> Co-ordinates
>> Lat: 52:13:08N (52.219)
>> Lon: 2:12:57W (-2.2159)
>>
>> Is my allotment facing SW or SSW?
>>
>> There is a bottle of Newcastle Brown Ale resting on the outcome.
>>

>
> At noon 1200 UTC, the Sun will be directly South and at 1800 UTC it will
> be directly West.


Errr... no it won't. The sun will on average be due south at local noon,
which isn't the same as UTC unless you're on the Greenwich meridian, and
he is 2 degrees and almost 13 minutes west of Greenwich. And the transit
of the sun is not clockwork - the exact time the sun is due south varies a
few minutes either side of local noon.

> At 1500 UTC it will be directly South West and SSW will occur at 1330, so
> at 1430 it is nearer SW.


Errr... no it won't. It would if the Earth were flat and the Sun was
infinitely distant, but neither of these things are true.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; An enamorata is for life, not just for weekends.
 
in message <W1%[email protected]>, Martin Dann
('[email protected]') wrote:

> Simon Mason wrote:
>> "Tom" <Don'[email protected]> wrote in message
>> news:[email protected]...


>> At noon 1200 UTC, the Sun will be directly South

>
> At noon local time the Sun will be directly south, so approx Noon 12:09
> UTC


More or less, depending on the date.

>> and at 1800 UTC it will be directly West.

>
> 52 degrees north is north of the tropic of cancer, so the sun can never
> be directly west of the OP.


Is the wrong answer. Consider you are at North Cape in Norway. At midnight
in June the sun is more or less due north - obviously the exact moment
that it is due north varies, as does the moment the sun is due south
around noon... But the point is that to get from due south to due north it
has to pass through due west.

Even here in Britain the sun in summer sets considerably north of the
east-west line. It doesn't cross the east-west line at exactly 0600/1800
hours, however, for all sorts of complicated reasons to do with spherical
geometry, the tilt of the Earth's axis relative to the ecliptic, and so
on.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; I'll have a proper rant later, when I get the time.
 
Simon Brooke wrote on 22/02/2007 08:13 +0100:
>
> It would if the Earth were flat and the Sun was
> infinitely distant, but neither of these things are true.
>


You're clearly not a physicist ;-)

--
Tony

"...has many omissions and contains much that is apocryphal, or at least
wildly inaccurate..."
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