Crossings
Sun–Mercury crossing
Known by name for what you say. Where a Sun line crosses a Mercury line on your map, both planets were on angles at the moment you were born, and the latitude through that point is a Sun–Mercury paran.
On this page
What the Sun–Mercury crossing means
Mercury is never more than about 28° from the Sun, and on this pair's map that fact counts for more than any reading. For one of the two to be on the meridian while the other rises or sets, Mercury's day has to be very short or very long, which only happens at high latitudes. So those crossings lie at about 60° north or south and beyond: through Norway, Finland, Iceland, Alaska and the north of Canada and Russia, and over open sea in the south. Lower down, a Sun–Mercury paran appears only where the two rise together or set together, and in practice that's in charts where Mercury was within about 15° of the Sun.
The reading is a voice that carries your name. Bylines, teaching, broadcasting, selling something you'd buy yourself, advice people pay for because it comes from you: astrocartography puts all of these under Sun–Mercury. With the Sun on the MC and Mercury on the horizon, the work is public and the talking is personal. With Mercury on the MC and the Sun rising, you're known for the ideas first, and people then want to meet whoever had them.
Combustion is built into this pair's catch. The charts that bring the paran down to where most people live are the ones with Mercury close to the Sun, which the tradition calls combust within about 8.5° and under the beams within about 17°. A combust Mercury is read as swallowed by the Sun, so what you think and who you are get hard to tell apart: a disagreement about an idea feels like one about you, and anything you don't care about is hard to write. The exception is cazimi, Mercury within about a quarter of a degree of the Sun's centre, which the old texts call the heart of the Sun and count as a strength.
Where they meet on your map
Your Sun MC and IC lines run from pole to pole, and so do your Mercury ones, so those four never meet. Each of them crosses the other planet's rising and setting curve once, which makes up to four crossings of a meridian line with a horizon line, and the rising and setting curves of the two can cross each other as well. Where they fall depends on the moment you were born: every chart has them, though some land in the middle of an ocean or too near a pole to be drawn.
At a crossing both planets were on angles in the same place at the same moment. Move east or west along that latitude and the same two still reach their angles together, only at another time of day, so astrocartography reads the whole latitude as a Sun–Mercury paran. Zenith Map draws it as a band 1° (about 110 km) either side, and its weight in a place's score fades with distance from the latitude.
Birth time
A wrong birth time moves every line, and the crossings with them: an hour's error puts each crossing 15° of longitude east or west, more than 1,600 km at the equator. The paran latitude hardly moves, because it depends on where the two planets were in the sky rather than on the time of day; in the engine's test charts an hour shifts it by about a tenth of a degree or less nine times out of ten. With an uncertain birth time, trust the paran before the crossing. What a doubtful birth time does to a map.
Questions
Is the Sun–Mercury crossing good for writers?
It's the pairing the tradition gives to writing under your own name, so on paper it's a natural fit for a book, a column or a byline. Check how close Mercury sat to the Sun at birth before relying on it: combust, it can make every draft feel too personal to finish. In charts without a low-latitude crossing, the two MC lines, which run pole to pole close beside each other, are the practical place to look.
Why is my Sun–Mercury paran so far north?
Because Mercury never gets more than about 28° from the Sun. For one to be on the horizon while the other is on the meridian, it has to rise or set within about two hours of the other's noon or midnight, and a day that short or that long only happens from about 60° north or south upwards. Charts with Mercury very close to the Sun also get a paran lower down, where the two rise or set together.
Mercury lines and the paran bands are drawn with Pro; the free map shows the Sun, Moon, Venus and Jupiter.