Could refraction by the earth's atmosphere have some relevance here?
Andrew
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of Greg Gómez
Sent: 31 August 2006 00:15
To: sundial@uni-koeln.de
Subject: Question about lunar phase and the sun's path in the sky
Hello Greg,
Let's ignore refraction for a moment, and just think about the celestial
hemisphere above your horizon.
When the sun transits at noon it is in the North-South plane that cuts the
hemisphere in two. But it isn't necessarily directly overhead. In fact it
won't be directly overhead on
Hello Greg and Chris,
While Chris explains your question well, I have several observations that
are related to your question. I am sure you have made the observations
also. But they are interesting. Who says the motions in the sky are
static?
1. At northern latitudes, in the summer, a
Greg,
Almost a month from now at the Autumnal equinox, Sept 23 this year I
believe, the sun will be on the celestial equator but the first quarter
moon (90 degrees from the Sun) will be 23.5 degrees plus minus about 5
deg from the celestial equator and thus below the horizon and will rise
Hi Larry:
Since you are interested in drawings that show the
different possibilities for sundial design, I thought you might like to have
this for your educational presentations.
I made this for a client so he could see the many
options for a perpendicular gnomon.These, I think, are the
John (and Larry),
I think there may be a problem with two of the seven designs. Numbering them 1 through 7 from left to right in your illustration, the problematic ones are No. 3 (the three-sided pyramid) and No. 4 (the three-sided pointed post).
All the others have the shadow axis of the pole,
Hi
John,
Remember my "Timelines" presentation at NASS Vancouver.This
outlined many interesting options for both time and date lines with
perpendicular gnomons. Fer De Vries program uses computation methods based on
perpendicular gnomons, even for sundials with polar gnomons. It is the tip
