Midpoint / Halbsumme

Midpoint (German Halbsumme; Latin medium punctum) is the middle point between two planets in the natal chart.

Ebertin's central technique. The central analytical technique of Reinhold Ebertin's (1901–1988) school and of Cosmobiology (#42).

The Formula

Simple arithmetic. Midpoint A/B = (longitude of A + longitude of B) / 2.

When it activates. A midpoint "activates" when a transiting planet, a direction (T091) or a progression (T090) lands on the point with an orb of up to 1.5°.

Notation of Midpoints

A/B = C notation. The notation A/B = C is used; for example, ☉/☽ = ♂ means "the Sun/Moon midpoint is activated by Mars" = integration of will and emotion through action.

The 90-Degree Dial

The compressed zodiac. Analysis is performed on the 90-degree Dial — a circular scale in which the zodiac is compressed to 90°, automatically aligning all aspects that are multiples of 90° (conjunction, square, opposition). This is Ebertin's unique visualization.

The Reference Book

Ebertin's "COSI". The basic reference is "COSI" (The Combination of Stellar Influences, 1940) by Reinhold Ebertin: it contains interpretations of all planetary midpoints.

What the Technique Reveals

Hidden connections. The technique uncovers hidden connections between planets not visible through classical aspects (T087). It is the "third eye" of the research astrologer.