What are midpoints?

A midpoint is the degree that sits exactly halfway between two planets. Sun at 10 degrees of Taurus and Moon at 20 degrees of Cancer give a midpoint at 15 degrees of Gemini, and an entire tradition of reading grew up around what happens when a third body lands on that spot. The method came out of Germany in the twentieth century and it works to far tighter measurements than ordinary aspect practice. The composite chart in Moon Shine AI runs the same arithmetic, applied across two complete charts rather than to one pair.

The arithmetic, and the midpoint people forget

Convert both positions to absolute longitude, add them, divide by two. Sun at 10 degrees of Taurus is 40 degrees around the circle. Moon at 20 degrees of Cancer is 110. The sum is 150 and half of that is 75, which reads back as 15 degrees of Gemini. The notation is written Sun/Moon, where the slash means midpoint and not division, and that shorthand is used throughout the literature.

Every pair produces two midpoints rather than one. The degree 180 away from the first is equally halfway between the two planets, measured the long way around the wheel, and in the example above that is 15 degrees of Sagittarius. Most writers call these the near and far midpoints, or the direct and indirect. Both are treated as live in the tradition, which immediately doubles the number of sensitive degrees any chart is carrying.

A midpoint is not a body. There is nothing at all in that part of the sky. It is a calculated degree that only acquires meaning when something else occupies it, which is the same logic that sits behind the Arabic parts and the vertex. The difference in scale is what matters here. Those points arrive one at a time, while midpoints exist for every possible pair and therefore arrive in quantity.

Witte, Ebertin and the half sum

The technique was built in Hamburg. Alfred Witte, working from the early 1920s, developed what became known as the Hamburg School, reading charts through midpoints and a rotating dial rather than through an aspect grid. The German word for a midpoint is Halbsumme, literally half sum, and that remains the standard term in German language practice today, which is a small but useful reminder of where the whole approach originates.

Reinhold Ebertin came out of that lineage and pared it back. He dropped the hypothetical planets the Hamburg School had introduced and published Kombination der Gestirneinflüsse in 1940, which appeared in English as The Combination of Stellar Influences and is still the reference work people reach for. He named his own approach cosmobiology and kept it deliberately close to what could be observed and checked.

The working unit is the planetary picture, written A/B = C, meaning that planet C occupies the midpoint of A and B. Sun/Moon is the classic case, read in that tradition as the meeting point of the two lights and given particular weight in relationship work. Ebertin's entries run to a few lines each, and they are compressed rather than complete. Treating them as finished interpretations rather than as starting notes is the most common way the method gets misused.

Hard aspects only, and a dial to find them

Midpoint work does not use the full aspect list. Contacts are counted from the eighth harmonic series alone, meaning conjunction, semi-square, square, sesquiquadrate and opposition, which is 0, 45, 90, 135 and 180 degrees. Trines and sextiles to a midpoint are generally not read at all. That is a real methodological difference from ordinary aspect practice, and it catches most people out the first time they try the technique.

The reason is as much practical as theoretical. A 90 degree dial folds the circle into four so that conjunction, square and opposition all align on one mark, and a 45 degree dial folds it again and brings the two minor octiles onto the same line. Set the pointer on a midpoint and everything in the series appears as a single visual alignment. The instrument and the method were designed together, which is why the aspect restriction feels arbitrary when it is lifted out of its own context.

Orbs are correspondingly narrow. Ebertin worked at roughly a degree and a half and frequently tighter, while dial practice often goes inside a single degree. That is not fussiness for its own sake. It is the only thing standing between the method and a system that returns a result for every question anyone puts to it.

The counting problem, said out loud

Ten planets plus the Ascendant and the Midheaven give twelve points, and twelve points produce sixty six pairs. Each pair carries two midpoints, and each midpoint is live at five positions in the eighth harmonic series. Multiply it out and a single chart contains several hundred sensitive degrees. Something will always be sitting near something, and any honest account of this technique has to start by admitting that.

What keeps the method usable rather than infinitely flexible is discipline applied in advance rather than afterward. Fix the orb before you look. Restrict yourself to midpoints that involve a personal planet or an angle. Decide whether you are using both midpoints of a pair or only the near one, and hold to that decision across the whole chart. A midpoint list assembled after the fact, selected because it agrees with a conclusion already reached, tells you nothing you did not bring in with you.

Birth time deserves its own note. The Ascendant advances about a degree every four minutes, so any midpoint it belongs to shifts by half that rate, and an uncertain birth time puts a large part of the midpoint structure beyond reach. With planetary midpoints the exposure is much smaller, since the Moon is the only body moving fast enough for a few minutes of error to change anything you would notice.