Midheaven

The Midheaven, or Medium Coeli, is the highest point of the ecliptic in a chart, the point where the ecliptic crosses the celestial meridian, the great circle running through the north and south points of the horizon and the zenith directly overhead, on its upper, culminating branch. It is the cusp of the tenth house and one of the four angles, and unlike the horizon based Ascendant and Descendant it depends on the meridian, a separate great circle fixed by an observer's geographic longitude rather than by the horizon at all.

The Latin name means "middle of the sky" and corresponds to the Greek mesouranema used for the same point by Hellenistic astrologers such as Vettius Valens, whose second century Anthologies pair the midheaven with the ascendant as the two principal kentra, or centers, of a chart. Ptolemy's Tetrabiblos likewise treats the Midheaven as one of the four governing angles, and Firmicus Maternus, in his fourth century Latin Mathesis, ranks it as the second best of the twelve places after the ascendant itself, using the term medium coelum. Because the meridian is fixed by an observer's geographic longitude and the moment of birth rather than the date alone, the Midheaven, like the Ascendant, is one of the points that makes a chart specific to an exact time and place rather than a generic reading for a given day.