As I suggested earlier, if you live within either the north or south TROPIC ZONE, your body will for part of the day be north-of ("over") the Ecliptic and will for part of the day be south-of ("under") the Ecliptic. This means you will experience two opposite signs in one day! Person B in the following drawing shows why.
A person living directly on the equator will spend (on an given day of the year) twelve hours over the ecliptic (in one sign) and twelve hours under the ecliptic (in the opposite sign). No matter what longitude an equator resident occupies, he will find himself switching at the real local times (RLT) shown in the twelve Sign-Switch Graphs (give or take no more than five minutes margin of tolerance). You will note that the progression of days in the Earth’s yearly round trip has a backward “drift” of an average of four minutes per day. However, because we must fit 365+ days into our 360 degree sign-circle, we must occasionally introduce a three-minute adjustment to account for an additional drift time of about twenty-one minutes (5.25 days x 4 = 21 min.). You will note that these 3-minute adjustments occur l7 days apart (365 days/21 min. = 17 days).
We can think of person B (in figure above) on the equator as describing (daily) an “over” and “under” sine wave in respect to the line of the ecliptic: 12 hours “over” and 12 hours “under”. But in this regard let me remind you that traditional viewpoints die hard, and perhaps one of the strongest (never-to-die) traditions is our refusal to view the world globe as shown below.
It appears “upside down” (south pole on the top and north pole on the bottom). And yet, one view is just as valid as the other (if we disregard tradition). But, have no fear, I will not insist on this extremely radical viewpoint and will continue to use the terms “over” or “above” to mean NORTH and to use the terms “under” or “below” to mean SOUTH. Also in describing the two PEAKS of the sine waves above and below the ecliptic, I will use the two terms “crest” and “trough”: the peak above (north) of the ecliptic will be called the “crest”, and the peak below (south) of the ecliptic will be called the “trough”.
Naturally, if you live-in or were born-in a tropic zone, you might want to know at what time your body switches from north to south or from south to north at any given day of the year. It is possible to calculate this with the help of the "Equator Sign-Switch Graphs" which give the switch times for the days of the year IF you live ON THE EQUATOR. This means that for other latitudes in the tropics you will need to use a "calculation formula" to adjust north or south of the equator time. You will find this calculation formula explained in the section immediately following the twelve "Equator Sign-Switch Graphs".
(It is our hope some day to have this calculation formula computerized to serve you better).
