Meaning and Notation

The Midheaven marks the culminating degree of the ecliptic above the horizon, the highest a degree of the zodiac climbs along the meridian before beginning to descend toward the western horizon, and it stands among the defining points of the Hellenistic horoscope alongside the Ascendant. Unlike the Ascendant and Descendant, which move along the horizon, the Midheaven is fixed by the meridian, an independent great circle, so it must be calculated separately from the rising degree rather than derived from it, a distinction already implicit in the Hellenistic practice of treating horoskopos and mesouranema as related but separately computed kentra, from a Greek root meaning either a driving goad or a turning pivot, an image for the angles as the points that seem to drive a chart's rotation.

In current notation the Midheaven is abbreviated MC, from the Latin Medium Coeli, and it is conventionally drawn at the top of the modern circular wheel chart regardless of whether that position corresponds to true north on the ground, a habit inherited from the older square horoscope format that was standard for over a thousand years before the circular wheel became typical only around the nineteenth century. MC remains one of the few angle abbreviations that keeps its Latin form intact in ordinary astrological usage.