The Astrolium local space astrology calculator returns the azimuth and altitude of each planet from your birth horizon, plus a Cozzi polar projection wheel with cardinal alignments and directional lines marked. Math runs on the Swiss Ephemeris, topocentric. Free, no signup.
Local space charts answer a question other chart types do not: where does each planet's energy point in physical space, from your birth location. Steve Cozzi worked out the modern form in the 1980s, but the underlying tradition is older: horizon-coordinate astrology goes back to medieval Arabic sources and was used by Ptolemy. The chart returns each planet's azimuth (compass bearing) and altitude (above or below horizon) at the moment of birth.
What the chart shows
Each planet at the moment of birth had a specific direction in physical space relative to your local horizon. The calculator computes that direction in two coordinates. Azimuth: the compass bearing from North, going eastward (0 = N, 90 = E, 180 = S, 270 = W). Altitude: the angle above or below the horizon (+90 at zenith, -90 at nadir, 0 at the horizon ring).
A planet at azimuth 247, altitude -23 was below the horizon at the WSW direction at birth. A planet at azimuth 92, altitude +14 was just above the horizon to the East. Both are real positions, and Cozzi's tradition reads them as the planet's directional signature.
Local space lines and directions
The primary application is locational. Each planetary azimuth defines a great-circle line on Earth's surface starting from your birth location and traveling outward in that compass direction. The line is the planet's directional reach across geography.
Moving along your Jupiter line is moving into Jupiter's domain; settling on your Saturn line is committing to Saturn's lessons. The Venus line points toward cities and regions where Venus themes intensify; the Mars line toward places where Mars activates.
The calculator returns the raw azimuth and an annotated directional list. For the world-map projection of these lines, see the astrocartography calculator. The two tools work together: local space gives you the bearings at birth; astrocartography projects them to geography. Practitioners working a relocation question typically run both, then look for cities where multiple lines coincide.
Cardinal alignments
When a planet's azimuth falls within a few degrees of a cardinal direction (N, E, S, W), the chart marks it as a cardinal alignment. A natal Mars azimuth at 87 is read as Mars-on-East. The cardinal alignment list uses a 2-degree default orb (configurable to 1 or 3 degrees). Practitioners read cardinal-aligned planets as having an unusually concentrated directional signal in that life area.
Cardinal alignments are the local space equivalent of angular planets in a standard chart: the most expressed, most active part of the directional layer.
Above-horizon versus below-horizon
The Cozzi projection shows both. Above-horizon planets sit inside the horizon ring; below-horizon planets sit in the annular band beyond the ring. Above-horizon planets are sometimes read as more externally expressed, the parts of the chart visible to others; below-horizon planets as more internal or psychological. The distinction is not absolute (a 9th-house Sun in geocentric terms is often above the horizon at noon births and below at midnight births) but it adds a layer the conventional natal scan does not.
For the local horizon framework this depends on, see the natal chart feature. For the location-driven extension of local space, see the astrocartography calculator. For the related relocation-shift chart, see the relocation chart calculator.