Local space: which direction each planet lies from where you are

The difference in one sentence

An astrocartography line is a fact about the Earth: your Venus rising line runs where it runs, and somebody standing on it in Portugal is on the same line as somebody standing on it in Ireland. A local space direction is a fact about a point: from your birthplace, Venus lay at a bearing of 47 degrees, and walking or flying along that bearing is the technique's idea of moving towards Venus.

The practical consequence is scale. Astrocartography has nothing to say about which side of a city to live on, because the whole city sits between two lines hundreds of kilometres apart. Local space will answer that question, because a bearing from your front door is as meaningful over two miles as over two thousand.

How the bearings are worked out

The planet's position is converted from the ecliptic coordinates a chart uses into the horizon coordinates an observer standing at a specific place would see: an azimuth, which is the compass direction, and an altitude, which is how high above or below the horizon it sat.

A planet below the horizon still gets a bearing. That is worth stating, because it surprises people: the direction is where it lay, not whether it was visible. Half the chart is always underfoot at any moment, and a local space line to a planet below the horizon is treated the same way as one above it.

The lines themselves are great circles, so a bearing followed far enough curves on a flat map the way a flight path does. Over the distances the technique is usually used for, that difference is invisible; over a continent it is not.

What it is used for

Two things, and they are different sizes. The large use is the same as astrocartography: choosing where to travel or move, by following a bearing rather than finding a line. The small use has no astrocartography equivalent at all, and is the more interesting one: which direction to face a desk, which side of a town to look for a flat, which way to walk when you want a particular kind of day.

The tradition here is thinner than for the angle lines, and it is worth saying so. Local space was popularised by Michael Erlewine in the 1970s, which makes it recent, and the small-scale applications are recent even by that standard.

What it cannot tell you

It cannot rank places. A bearing points at an infinite line of them, and everything along that bearing shares the direction while having nothing else in common. Astrocartography with a city list will tell you that Lisbon suits your chart better than Lyon; local space will only tell you that both lie towards Venus from where you started.

It is also anchored to one place, so the answer changes when you move. Local space from your birthplace and local space from where you live now are two different compasses, and the tradition does not entirely agree about which one to use. This site computes from the birthplace by default and says so.

Frequently asked questions

Is local space the same as astrocartography?

No. Astrocartography draws lines that are fixed on the globe and the same for anybody born at that instant. Local space gives compass bearings from one specific place, so it changes depending on where you measure from. They are complementary rather than alternative: the map answers where, and the compass answers which way from here.

Does a local space line work over a short distance?

That is the claim, and it is the main reason the technique exists alongside astrocartography. A bearing is as well defined over two miles as over two thousand, which is why local space is used for choosing a room or a street when a world map has nothing useful to say at that scale.

Do I need my birth time for local space?

Less than for astrocartography, but it still helps. The planetary positions themselves move slowly, so the bearings are roughly right from the date alone. What needs the time is the horizon itself, so anything about a planet being above or below it is only as good as the time you have.