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Parallels of Latitude & Declination (Part 1)

Figure A shows the Earth, on which we have drawn both parallels of geographic latitude and north/south geographic meridians of longitude. Point 'a' illustrates a city located somewhere (we can imagine) in the mid-West. Any atlas will allow you to find other cities (by geographic longitude & latitude) located along the parallel of latitude where you are and also cities located along the north/south geographic meridian that passes through your location. We have illustrated this with small circles in the diagram that represent other cities located along these two directions on the globe.

We have seen how there is a circle of stars on the celestial sphere that equals the circle of geographic latitude for any spot on Earth. We can do the same for the geographic longitude factor. In fact we do this each time we cast a natal chart and locate the Local Sidereal Time (LST) or Right Ascension of the Mid-Heaven (RAMC). We stop the Earth's motion and hold it still (frozen in time) to see what part of the heavens is overhead our birth place. Another way of saying this: we determine in what direction of the heavenly sphere the Earth was pointed or oriented.

Once we have found the LST or RAMC for a birth, we can look up the equivalent midheaven (M.C.), ascendant, and house-cusps in any table-of-houses. We can also look up the direction of the heavens "out-there" or overhead on the star maps elsewhere in this section. Your LST. (Local Sidereal time) may be expressed in Hours-Minutes-Seconds (HMS), which you will find along the edge of these maps or in Degrees-Minutes-Seconds (DMS) of arc (rather than time). These too are given on the maps. (HMS may be converted to DMS by simply multiplying by 15, and DMS may be converted to HMS by dividing by 15).

© Copyright © 1997 Michael Erlewine