-----Original Message-----
From: Eric Johnson <ej@tx3.com>
To: Richard D. Joffe <rdjoffe@erols.com>; wwpotter@tscnet.com
<wwpotter@tscnet.com>
Date: Friday, December 04, 1998 8:31 PM
Subject: RE: Low Tech Navigation
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> West Wight Potter Website at URL
> http://www.lesbois.com/wwpotter/
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>> Extra credit: You may also use the height of the North Star
>> (Polaris) above
>> the horizon. It should be directly overhead (90 degrees) at the
>> North Pole
>> on the equinoxes, and on the horizon at the equator. On any other day,
>> you've have to make an adjustment.
>
>Thats true for the sun, but isn't polaris due north (within a degree or
two)
>regardless of the date?
Polaris is always due North, but its height above the horizon is what gives
your latitude. This should vary with the date, just as the height of the
sun varies with the date. Both start at the true latitude (measured in
degrees from the horizon) at the Vernal Equinox, then appear higher and
higher in the sky until the Summer Solstice, when the sun is directly
overhead at the Tropic of Cancer, then descend until the true latitude is
reached on the Autumnal Equinox (height of the sun/Polaris above the horizon
equals the number of degrees from the equator to your location), then
descend until they reach their lowest height at the Winter Solstice, when
the sun is directly overhead at the Tropic of Capricorn. It's all because
the earth is tilted about 23 1/2 degrees on its axis.
Richard D. Joffe
rdjoffe@erols.com
P-15 #2080, "Potter Noster"
Columbia, MD