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Hi Herb-
My source is Kline, <Mathematical Thought>. Yours?
And "Howdy" yourself, from a native Montanan.
Regards,
Jack
On Fri, 14 Sep 2001, Herb Schulz wrote:
>Hi-
> You can take this demo one step further by thoughtful positioning
>of your light source, ball, and observer. The Greeks measured the
>distance to the sun by noting when the moon was at exactly 1/2 lit, and
>measuring the angle between the lines of sight to the sun and moon. They
>knew the lunar distance from parallax (I wouldn't call that
>"triangulation" I don't think), in units of the earth's radius.
> Their number for the solar distance was not too good, as I recall,
>because the relevant angle is so close to pi/2.
> Regards,
> Jack
Howdy,
I thought the original measurement of the Earth-Moon distance (in
units of the diameter of the Earth - know from Egyptian measurements)
used the fact that the cone of the Earth's Dark Shadow would have a
base of the Earth's Diameter and an opening angle of about 1/2 degree
(the angular size of the Sun at the Earth) and determining, the the
time of the Moon's entry till its exit from that Shadow in a Total
Lunar Eclipse gave the size of the Moon (also a 1/2 Degree angular
size from the Earth) was approximately 3/8 the diameter of the
Earth's Shadow at that distance. That is a Unique Distance.
Good Luck,
--
Herb Schulz
(herbs@interaccess.com)
--
Franz Kafka's novels and novella's are so Kafkaesque that one has to
wonder at the enormity of coincidence required to have produced a writer
named Kafka to write them.
Greg Nagan from "The Metamorphosis" in
<The 5-MINUTE ILIAD and Other Classics>